GB2054135A - Photo-electric Displacement Transducer - Google Patents
Photo-electric Displacement Transducer Download PDFInfo
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- GB2054135A GB2054135A GB7925195A GB7925195A GB2054135A GB 2054135 A GB2054135 A GB 2054135A GB 7925195 A GB7925195 A GB 7925195A GB 7925195 A GB7925195 A GB 7925195A GB 2054135 A GB2054135 A GB 2054135A
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- signals
- displacement
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- light
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- 238000006073 displacement reaction Methods 0.000 title claims abstract description 122
- 230000003068 static effect Effects 0.000 claims description 41
- 239000000470 constituent Substances 0.000 claims description 30
- 230000008878 coupling Effects 0.000 claims description 17
- 238000010168 coupling process Methods 0.000 claims description 17
- 238000005859 coupling reaction Methods 0.000 claims description 17
- 230000003252 repetitive effect Effects 0.000 claims description 13
- 230000003019 stabilising effect Effects 0.000 claims description 10
- 230000003993 interaction Effects 0.000 claims description 6
- 238000013500 data storage Methods 0.000 abstract description 10
- 230000000694 effects Effects 0.000 abstract description 6
- 239000003381 stabilizer Substances 0.000 description 62
- 239000011521 glass Substances 0.000 description 21
- 230000033001 locomotion Effects 0.000 description 16
- 238000000034 method Methods 0.000 description 14
- 230000004907 flux Effects 0.000 description 10
- 230000008859 change Effects 0.000 description 7
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- 230000000996 additive effect Effects 0.000 description 4
- 230000004044 response Effects 0.000 description 4
- 125000004122 cyclic group Chemical group 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000012886 linear function Methods 0.000 description 2
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- 230000006641 stabilisation Effects 0.000 description 2
- 101100500641 Oscheius tipulae eft-3 gene Proteins 0.000 description 1
- 230000009471 action Effects 0.000 description 1
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- 230000032683 aging Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
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- 230000003247 decreasing effect Effects 0.000 description 1
- 238000000151 deposition Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
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- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 description 1
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- 238000009958 sewing Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000002463 transducing effect Effects 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
- G01D5/32—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light
- G01D5/34—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light with attenuation or whole or partial obturation of beams of light the beams of light being detected by photocells
- G01D5/36—Forming the light into pulses
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/26—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/08—Disposition or mounting of heads or light sources relatively to record carriers
- G11B7/085—Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam into, or out of, its operative position or across tracks, otherwise than during the transducing operation, e.g. for adjustment or preliminary positioning or track change or selection
- G11B7/0857—Arrangements for mechanically moving the whole head
- G11B7/08582—Sled-type positioners
- G11B7/08588—Sled-type positioners with position sensing by means of an auxiliary system using an external scale
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Length Measuring Devices By Optical Means (AREA)
Abstract
An apparatus for the determination of displacement, particularly for use as the position sensing element in a servomechanism for a read/write head on a data storage disc, produces a plurality of displacement indicating signals (4). The signals are such that they possess a sum ( SIGMA ) or other combination which is independent of the displacement and the result of that combination is compared with a predetermined level (9). The amplitudes of the signals are collectively adjusted such that the result of the combination is equal to the predetermined level. This has the effect of cancelling long and short term drifts on the signal amplitudes e.g. due to changes in light source 1. The light passes through a moving scale 2 and fixed scale 3 to detectors 4 giving sets of signals phased 90 DEG apart. <IMAGE>
Description
SPECIFICATION
Displacement of Transducing Means 1. Field of the Invention
The present invention relates to a method and apparatus whereby determination of relative displacement between two constituent members, and the provision of output indicative of that displacement, may be achieved with freedom from long and short term amplitude errors in the plurality of displacement indicating signals forming the output. The apparatus is intended for use as the position sensing element in precise, position control servomechanisms. In particular, the present invention is of utility as the position sensing element of head positioning servomechanisms found in high radial track density disc files.
2. The Prior Art
In the course of development of data storage disc files, there has been a steady trend towards higher numbers of concentric, data storage tracks per radial inch of the disc, so increasing the data storage capacity of the disc by increasing the total number of tracks available. Attempts to yet further increase the data storage capacity of the discs are forcing the radial track density to even greater values.
In order to operate successfully as high radial track densities it is necessary to position the data depositing and retrieving head with great precision over specific radii on the disc, so as to allow the head to pick out one particular data storage track from among the close adjacency of other tracks. Failure to achieve the required precision of head positioning caused the head to interact with tracks adjacent to that with which it is intended that is should interact, so rendering unrelitable the recovery of data, and allowing the overwriting and attendant destruction of data it is intended to preserve.
Radial track densities on discs were, for a long time, held at a low value by the limitations of head and disc technology. The densities encountered were typically between forty and a hundred tracks to the radial inch. At these low densities, it was possible to achieve sufficient accuracy in head position by using an open loop head positioner. Systems were employed such as a stepping motor driving a lead screw or belt assembly.
Improvements in head and disc technology later allowed the track density found on rigid discs to exceed two hundred tracks to the radial inch.
At these higher track densities, the open loop approach to head positioning had to be adandoned, because of the errors induced by friction and random device variations. The use of low friction, voicecoil actuators was adopted as a common standard. The actuators were employed as the moving member in a closed loop, head positioning servomechanism. The position of the head was found using an optical position sensing transducer. The transducer output, coupled as the controlled input to the servomechanism, comprised a plurality of sinusoidal position indicating signals with regular radial repetition distance and evenly distributed phase separation between the different signals. This represented, and still represents, the most economical way of achieving the necessary position measuring accuracy of less than one ten thousandth of an inch.A lightsource, shining through a glass slide attached to the actuator, on which are imprinted a plurality of opaque lines, sends a beam of light through the slide, through a plurality of static masks, similar to the slide, and onto a plurality of photosensors behind the masks, each photosensor providing one of the plurality of sinusoidal position indicated signals. The positioning servo caused the head to come to rest at those positions where the value of the sinusiodal position indicated signals was zero.
This method allowed the head to take up any one of a plurality of evenly spaced radial rest positions accross the disc. Each rest position corresponded to the head's being nominally over a particular data storage track.
The introduction of the flexible disc highlighted at far lower track densities, problems which only become significant for rigid discs at track densities in excess of two hundred to the radial inch. At still higher densities, on rigid discs, and at around seventy tracks to the radial inch on flexible discs, dimensional instability of the disc and the disc file causes unacceptable errors in the accuracy of head positioning over data storage tracks on the disc.
The material of which the disc file is made expands and contracts with different thermal and humidity constants than the material of the disc.
The actuator being attached to the disc file, and the head being attached to the actuator, the data storage tracks on the disc appear to change their radial position relative to the rest positions of the head. This causes a positional error between head and track which is the same for all tracks. The expansion and contraction of the disc itself causes the distance between track to alter. The repetition distance of the position transducer signals no longer equals the repetition distance of the tracks.
Each track aquires a displacement from its nominal position which is different from that for any other track.
In either case, the head is no longer correctly positioned over the data storage tracks when situated at the zero levels of the position transducer output signals. While certain, limited amounts of these mispositioning effects can be tolerated, there comes a critical radial track density, above which it is necessary, as a regular operating feature, to alter the position of the head interpolatively between adjacent points represented by adjacent zero levels of the position transducer output.
The actual amplitudes of the sinusoids forming the output of the position transducer was of no particular concern when it was only required to position the head at the point where the sinusoids were zero. No matter what the amplitude of the sinusoid, its zero point remains in the same position. In an interpolative action, however, where the head is caused to take up a position other than at the zero point of the position transducer signals, by the application of a positional demand signal to a summing junction in the servomechanism, the position that the head takes up, in response to a particular size of demand signal, is a distance away from the zero point of the transducer signal which is a decreasing function of the amplitude of the sinusoid.In order that the same distance may be moved for the same size of demand signal, it is necessary that the amplitude of the sinusoidal output signals of the position sensing transducer be held at a constant, known value.
The problems which beset the stability of the amplitudes of the output signals of an optical transducer involve long and short drift in the component parts of the optical generating and sensing path. The output of the light source changes slowly with age. Both solid state light emitters and incandescent bulbs experience a slow, relentless reduction in their emission efficiency with time, bringing about a corresponding reduction in the amplitudes of the position indicating sinusoidal output signals of the transducer. The light emitters also experience a short term variability of their intensity of light output with changing ambient temperature. The sensitivity of light sensor is also a function of changing temperature.Dust and other debris, slowly building up along the path of the light beam, particularly on the light transmitting glasswork, causes a steady reduction in the proportion of the emitted light which reaches the photosensors. Each of these effects has an adverse effect on the predictability of the amplitudes of the position indicated signals.
There have, to date, been two broad areas of solution to the problem of drift. In a first method, the ambient temperature is monitored, and the level of drive to the light source altered in anticipation of the probably effect of temperature change. This has the twin disadvantages of being an open loop process, operating regardless of its actual effect, and doing nothing about the aging og yhr lightsource or the build up or debris on the glasswork.
In a second method, an extra photosensor is included in the position transducer assembly.
Although in the light beam passing through the glasswork, it is arranged that the light impinging on the extra photosensor is free from modulation, and is represented by a steady level regardless of the position of the actuator. The output of the extra photosensor is monitored, and the output applied as the controlled input to a light stabilising servo. The servo turns the intensity of the light source appropriately up or down so that the output of the extra photosensor equals a predetermined level. This approach is successful provided great care is taken to see that the environment of the extra photosensor closely matches that of the other photosensors.The method has the disadvantages of being partially open loop, since the output which it is desired to control is not in fact monitored, and of increasing the already considerable price and complexity of the optical assembly of the position sensing transducer.
It therefore becomes desirable to provide a method and apparatus whereby the actual position signals themselves may be monitored and stabilised, at the minimum of expense and addition of components.
Objectives of the Present Invention
Accordingly, it is a prime objective of the present invention to provide a method and apparatus whereby the above objectives may be achieved.
It is a particular objective of the present invention to provide a method and apparatus for the transductive measurement of displacement, the amplitudes of the output signals indicative of that displacement being independent of time and temperature.
It is another particular objective of the present invention to provide an apparatus for use as position sensing element in a position control servomechanism.
It is another particular objective of the present invention to provide a position control servomechanism whose positional response to a particular level of input demand is constant with time and temperature.
It is a final and most particular objective of the present invention to provide a servomechanism for the positional control of the radial position of a head in a disc file where the change in the radial position of the head for a particular change in the demand level is independent of time and temperature.
Brief Description of the Invention
In accordance with the present invention, there is provided a transducer for the indication of the relative position between two constituent members, the members being constrained to move relative to one another along a known path, the first member being mobile and the second member being static, the second member, responsive to the passage past it of the first member, providing as its output a plurality of signals collectively responsive in their amplitudes to a driving input, and indicative of the relative position between the two members, the signals being regularly repetitious with respect to the relative displacement, non zero in their mear value against displacement, equal in amplitude to each other, and having a uniform phase spacing between each other, relative to the displacement, leading to their sum being independent of the extent of motion, where the signals are provided as inputs to an amplifier having, as its output, a representation of the difference between the sum of the signals and a fixed reference level, and whose output is provided as the driving input to the static member, in such a sense that an increase in the sum of the signals causes a reduction in the amplitudes of the signals, thereby ensuring that the amplitudes of the signals are collectively held constant.
In the preferred embodiment of the present invention, there if provided a transducer for the indication of the relative position between two constituent members, the members being constrained to move relative to one another along a rectilinear path, the first member being mobile and comprising a light transmitting, laminar glass slide, the glass slide having its plane normal to the direction of rectilinear motion and having deposited on it a plurality of opaque, regularly spaced lines, the lines having width equal to half of their repetition distance, and their direction of point normal to the rectilinar relative motion between the two members and the second member being static, comprising a lightsource whose intensity is responsive to a driving input, four light transmitting photomasks, and a block bearing four linearly responsive photosensors, the lightsource providing a beam of light which is normal to the plane of the glass and the rectilinear motion, the light beam shining firstly, through the glass slide, secondly, through the photomasks, the photomasks being positioned one between the glass slide and each of the photosensors, the photomasks being laminar with plane parallel to the plane of the glass slide, the photomasks being attached to the static block, and having deposited on each of them, an individual set of opaque lines, parallel and identical to those on the glass slide, and thirdly, the light beam shining onto the photosensors, the relative rectilinear displacement between the four sets of opaque lines, one on each of the individual photomasks, being such that their interaction with the opaque lines on the glass slide, modulating the intensity of the light beam reaching the photosensors, causes the outputs of the photosensors, which form the position indicating output of the transducer, to comprise four triangular waves, the triangular waves being regularly repetitious with relative rectilinear displacement, non zero in their mean value against displacement, equal in amplitude to each other, and having a uniform phase spacing between each other, relative to the rectilinear displacement, leading to their sum being independent of the extent of rectilinear motion, where the four triangular waves are provided as inputs to an amplifier having, as its output, a representation of the difference between the sum of the four triangular waves and a fixed reference level, and whose output is provided as the intensity controlling, driving input to the light source on the static member, in such a sense that an increase in the sum of the triangular waves causes a reduction in the intensity of the lightsources, thereby ensuring that the amplitudes of the signals are collectively held constant.
The operating principles of the present invention, together with further aims and objectives thereof, may better be understood by consideration of the following description, read in conjunction with the appended drawings.
Brief Description of the Drawings
Figure one shows, in schematic and exploded form, the overall construction of the present invention.
Figure two shows the relationship between the opaque lines on the slide and the mask, together with the longitudinal positional relationship between the areas of line pattern on the mask.
Figure three shows the waveforms resultant at the outputs of the solar cells resultant from the passage, past the mask, of the slide.
Figure four shows an alternative form of shutter and mask, compatible with the spirit of the present invention.
Description of the Preferred Embodiment 1. Description of the Overall System
Attention is first drawn to figure one, showing in exploded and schematic form, the parts and system of the preferred embodiment of the present invention.
Acollimating light source (1), containing a driven light generator, in the form of an incandescent bulb, located behind and at the focus of a lens, generates a parallel beam of light which it sends firstly, through a laminar, movable, light transmitting glass slide (2), secondly, through a non mobile, laminar, light transmitting fixed photomask assembly (3), and thirdly, onto an array of four photocells (4), each of the photocells (4) turning the impinging light into an electrical signal directly proportional in its amplitude to the totality of light flux incident on the photocell (4). The glass slide (2) is alone mobile, out of all the parts shown, being movable to and fro, along a rectilinear path, in the directions indicated by the arrow (11).
The four outputs of the solar cell array (4) are coupled, as inputs, to a signal summing junction (5), which provides, as its output, the additive sum of its inputs. The output of the signal summing junction (5) as coupled as an additive input to the signal differencing junction (6). The signal differencing junction (6) has its subtractive input coupled to the output of a signal reference generator (9), which provides an unvarying output against which the additive input of the signal differencing junction (6) may be compared. The signal differencing junction (6), provides, as its output, the arithmetical difference between its additive and subtractive inputs. The output of the signal differencing junction (6), is coupled as an input to an inverting amplifier (7).The output of the inverting amplifier (7), a negative analog of its input, is coupled back to the light source (1), causing the intensity of the light beam to be modulated in response to the output level.
The glass slide (2) has deposited on it, by photographic techniques, a plurality of opaque lines (8) their long axes normal to the direction of motion of the slide (2), regularly spaced, and having a width equal to half of their repetition distance along the slide (2), so rendering opaque exactly 50% of the area of the slide (2).
The photomask assembly (3) has, deposited on it, again by photographic techniques, mask opaque lines (10). The mask opaque lines (10) are identical in their width, spacing and orientation, to the slide opaque lines (8). The photomask (3) is divided into four separate areas, shown later, each one out of the four areas providing the unique light transmission path to one, and one only, out of the four photocells (4), each photocell thus having its own, individual area of the photomask (4) through which it receives light.
The lightsource (1) generates a parallel beam of light whose direction is normal both to the plane of the glass slide (2) and the direction of motion of the glass slide (2). The photomas assembly (3) comprises a piece of glass similar to that from which the glass slide (2) is fabricated.
The plane of the glass of the photomask assembly (3) is parallel to the plane of the glass of the slide (2). The plane of both pieces of glass is normal to the direction of motion of the slide (2).
2. Detailed Description of the Glassware
Attention is next drawn to figure two, showing, in detail, comparative aspects of the slide (2), the slide opaque lines (8), the photomask assembly (3), and the four areas (12, 13,14 and 1 5) of the mask opaque line (10) on the photomask (3).
The mask opaque lines (10) are divided into four areas (12, 13, 14 a 1 5). Each area comprises one quadrant of the square mask assembly (13).
The mask opaque lines (10), within each quadrant, are identical and parallel to the slide opaque lines (8). The mask opaque lines (10), however, do not present a uniform continuity accross the photomask (3) as do the slide opaque lines (8) accross the slide, (2), since the mask opaque lines (10) are disposed with the line pattern within one quadrant being offset, in the direction of motion of the slide (2), relative to the line patterns in each of the other three quadrants.
The line pattern in the top righthand quadrant (13) is displaced by one line thickness, (half the repetition distance of the lines), from the line pattern in the lower right hand quadrant (14). The line pattern in the top lefthand quadrant (12) is displaced by one line thickness from the line pattern in the lower lefthand quadrant (15).
Between the left and righthand sides of the photomask assembly (4), there is a displacement between line patterns of one half of the line thickness; that is, if the line pattern from either half of one side of the photomask (3) were to be continued over into the other side, it would be found that the registration of the continued line pattern with the line pattern already on that side would be in error by one half of a line thickness.
There are thus four areas on the photomask assembly (4) each bearing a line pattern which has a different position, along the direction of motion of the slide (2), with respect to the other three, against any particular feature of the line pattern on the slide (2). Any line on the slide (2) will coincide with the line on each quadrant in turn, the points of coincidence between the lines on the slide (2) and the lines in each of the four quadrants being evenly distributed with respect to the motion of the slide (2).
Each one of the quadrants (12, 13, 14, 8 15) on the photomask (3) corresponds to the field of view of one of the photocells, (4), the individual photocells (4) receiving light through its designated quadrant, each quadrant providing light to only one photocell.
3. Description of the Origin of the Photocell
Signals The light beam is obstructed in its passage through the slide (2) and the photomask (3) by both the slide opaque lines (8) and the mask opaque lines (10). Maximum light flux is transmitted through the glass members (2 Eft3) and reaches the photocells (4) whenever the lines on the mask (10) lie exactly within the shadows cast by the lines on the slide (8). No light flux reaches the photocells whenever the two sets of shadows, cast by the two sets of lines, form a continuity, where the opaque parts of one line pattern block the path of the light which would normally get through the non opaque parts of the other line pattern.Between these two positions, of maximum and minimum light flux falling on the photocells (4), the amount of light reaching the photocells (4) is a linear function of the position of the slide (2) between the extremes. The slide opaque lines (8) progressively cut off or expose the area between the mask opaque lines (10), through which light may pass, so allowing less or more light flux to impinge onto the photocells (4).
The area of light visible to the photocells (4) is a linear function of the slide position. The photocells (4), being linear in their response to light flux, generate, as their outputs, electrical signals which are linear against the position of the slide (2).
The totality of light flux reaching each photocell is thus a linear interpolation, against the position of the slide (2), between the amounts of light arriving at the photocell with the slide (2) at the positions of maximum and minimum light.
The light flux on each photocell is cyclic with the distance moved by the slide (2), rising and falling as an offset triangular wave with period equivalent to a movement of the slide equal to the repetition distance of the line patterns. Since the line patterns in each of the quadrants (12, 13, 14 s 1 5) are offset from one another in the direction of motion of the slide (2), the position of the slide (2) at which each photocell (4) receives minimum and maximum light flux is different from the positions where the other three experience these conditions.
4. Phasing and Summation Properties of the
Signals
Attention is next drawn to figure three which shows the electrical output waveforms derived from the individual photocells (4) as the slide (2) traverses past the photomask (3). Figure 3A shows the output of the photocell in the top lefthand quadrant (12) of the photomask (3) as the slide (2) traverses from left to right as shown in figure two. Figure 3B shows the output from the photocell (4) in the top righthand quadrant, (13), figure 3C shows the output from the photocell (4) in the bottom lefthand quadrant, and figure 3D shows the output of the photocell (4) in the bottom righthand quadrant (14), under the same conditions. The phases of the outputs are uniformly staggered with respect to the motion of the slide (2).They may be described as four, offset triangular waves, of equal amplitudes, and phases of 0,90,180 and 270 degrees.
It will be seen that the signals, because of their complementary slopes, if summed, produce as their sum, a quantity which is independent of the position of the slide (2). In particular, the 0 and 180 degree outputs, summed together, independently posess this property, as do the 90 and 270 degree outputs. Since each set of outputs has this property, the sum of the two sets of outputs also has the property.
5. Description of the Stabilising Action
Attention is returned now to figure one. The sum of the photocell (4) output signals, fed to the signal differencing junction (6), provides an indication of the collective amplitudes of the signals, which indication does not change with the position of the slide (2) and so provides an indication of the correctness of the intensity of the light beam generated by the light source (1). This sum is employed as the controlled input of the closed loop servomechanism, which is, in essence, the preferred embodiment of the present invention, controlling the brightness of the lightsource (1), and comprising the cyclic, cooperation of the lightsource (1), the photocells (4) the summing and differencing junctions (5 8 6) and the inverting amplifier (7).
The output signals of the photocells (4) are externalised as the position indicating output of the transducer.
Any increase in the amplitude of the output signals of the photocells (4) causes a corresponding increase in the output of the signal differencing junction (6). If the sum of the signals is greater than the output of the reference generator (9) the output of the signal differencing junction (6) will be negative, and if greater, will be positive. The inverting amplifier (7), presented with a negative input change, increases the drive to the lightsource (1) and if presented with a positive input change, decreases the drive to the lightsource (1). In this way the intensity of the light beam, generated by the lightsource (1) is stabilised at that level where the sum of the outputs of the photocells (4) equals the output of the signal reference generator (9).
6. Other Implementations of the Present
Invention
Attention is now drawn to figure four. It will be apparent to those skilled in the art that other position indicated waveforms may fulfil the condition of having a sum independent of position. Two complementary ramps, for example, represent the extreme case where the repetition distance of the output of the photocells equals or exceeds the length of the slide. By way of example, a style of glass slide (16) and mask (19) are shown in figure four, which might equally well be employed in the present invention as opposed to the style, previously shown.There are provided two opaque wedges (17 and 18) deposited on the slide (1 6). Each wedges is independently viewed by one of two photocells, through apertures (20 and 21 ) one for each of the two photocells, in the mask (1 9). The light flux falling onto each photocell is modulated by the proportion of the apertures (20 Et 21j not covered by the wedges (17 8 1 8), and thus the two output signals of the photocells rise and fall in a complementary manner with the motion of the slide (16), cancelling each others changes, and so presenting, as their sum, a constant level, independent of the position of the slide.
It will also be apparant to those skilled in the art that not all of the waveforms generated and employed within the amplitude stabilising loop need be externalised as the transducer output, it being possible to generate complementary signals used purely for the stabilisation of a desired signal.
It will also be apparant to those skilled in the art, that the generator of the position indicated and/or complementary signals need not be optical, other signal generation methods falling within the spirit of the present invention.
It will also be apparant to those skilled in the art that stabilising method for positional transducer signals is not restricted to use on rectilinear position transducer; in particular, rotational motion transducers may readily be adapted.
It will also be apparant that the method of the addition of a complementary signal to another in order to achieve a steady level independent of any variable other than the signal amplitude, may be employed for the stabilisation of any signal whose amplitude may be modulated, the signal type not being restricted to the position domain alone, but encompassing any variable, such as time, against which signals may be mapped.
It will also be apparant that combinations of signals other than their sum may be employed to achieve an invariant result. In general, sums, products, differences, powers and roots of the instantaneous values of signals may variously be employed, alone or in combination, to achieve the required, invariant result.
Aspects of the Invention
According to one aspect of the present invention, there is provided an apparatus for the determination of displacement between two constituent members, the two members cooperatively providing an output indicative of the displacement, the output comprising a plurality of signals, the signals posessing a combination which is independent of the displacement, the signals being coupled as an input to a signal stabiliser, the amplitudes of the signals being collectively responsive to an output of the signal stabiliser, where the signal stabiliser forms the combination of the signals and compares that combination with a predetermined level, coupling the result of that comparison to its output, thereby collectively adjusting the amplitudes of the signals such that the combination equals the predetermined level.
According to another aspect of the present invention, there is provided an apparatus for the determination of displacement between two constituent members, employed as the position sensing element in a servomechanism, the two
members co-operatively providing an output
indicative of the displacement, the output
comprising a plurality of signals, the signals posessing a combination which is independent of the displacement, the signals being coupled as an
input to a signal stabiliser, the amplitudes of the signals being collectively responsive to an output of the signal stabiliser, where the signal stabiliser forms the combination of the signals and
compares that combination with a predetermined
level, coupling the result of that comparison to its
output, thereby collectively adjusting the
amplitudes of the signals such that the
combination equals the predetermined level.
According to another aspect of the present invention, there is provided an apparatus for the determination of angular displacement between two constituent members, employed as the position sensing element in a servomechanism, the two members co-operatively providing an output indicative of the displacement, the output comprising a plurality of signals, the signals posessing a combination which is independent of the displacement, the signals being coupled as an input to a signal stabiliser, the amplitudes of the signals being collectively responsive to an output of the signal stabiliser, where the signal stabiliser forms the combination of the signals and compares that combination with a predetermined level, coupling the result of that comparison to its output, thereby collectively adjusting the amplitudes of the signals such that the combination equals the predetermined level.
According to another aspect of the present invention, there is provided an apparatus for the determination of rectilinear displacement between two constituent members, employed as the position sensing element in a servomechanism, the two members cooperatively providing an output indicative of the displacement, the output comprising a plurality of signals, the signal posessing a combination which is independent of the displacement, the signals being coupled as an input to a signal stabiliser, the amplitudes of the signals being collectively responsive to an output of the signal stabiliser, where the signal stabiliser forms the combination of the signals and compares that combination
with a predetermined level, coupling the result of
that comparison to its output, thereby collectively
adjusting the amplitudes of the signals such that the combination equals the predetermined level.
According to another aspect of the present
invention, there is provided an apparatus for the determination of displacement two between two constituent members, the two members cooperatively providing an output indicative of the displacement, the output comprising a plurality of signals; the signals posessing a combination which is independent of the displacement, the signals being coupled as an input to a signal stabiliser, the amplitudes of the signals being collectively responsive to an output of the signal stabiliser, where the signal stabiliser forms the combination of the signals and compares that combination with a predetermined level, coupling the result of that comparison to its output, thereby collectively adjusting the amplitudes of the signals such that the combination equals the predetermined level, and where the two constituent members comprise a static and a moving member, the moving member, traversing past the static member and also including a plurality of indices, which traversw past a Ipurality of index detectors included in the static member, each one of the index detectors providing an output responsive to the traversing of each one of the indices, each one of the outputs of the index detectors providing one of the plurality of displacement indicating signals.
According to another aspect of the present invention, there is provided an apparatus for the determination of displacement two between two constituent members, the two members cooperatively providing an output indicative of the displacement, the output comprising a plurality of signals, the signals posessing a combination which is independent of the displacement, the signals being coupled as an input to a signal stabiliser, the amplitudes of the signals being collectively responsive to an output of the signal stabiliser, where the signal stabiiiser forms the combination of the signals and compares that combination with a predetermined level, coupling the result of that comparison to its output, thereby collectively adjusting the amplitudes of the signals such that the combination equals the predetermined level, and where the two constituent members comprise a static and a moving member, the moving member, traversing past the static member and also including a plurality of indices, which traverse past a plurality of index detectors included in the static member, each one of the index detectors providing an output responsive to the traversing of each one of the indices, each one of the outputs of the index detectors providing one of the plurality of displacement indicating signals, the signals being regularly repetitive with respect to the displacement, and evenly distributed with respect to the displacement, each signal having a non zero mean value, the combination of the signals employed by the signal stabiliser being a summing of the signals.
According to another aspect of the present invention, there is provided an apparatus for the determination of displacement two between two constituent members employed as the position sensing element in a servomechanism, the two members co-operatively providing an output indicative of the displacement, the output comprising a plurality of signals, the signals posessing a combination which is independent of the displacement, the signals being coupled as an input to a signal stabiliser, the amplitudes of the signals being collectively responsive to an output of the signal stabiliser, where the signal stabiliser forms the combination of the signals and compares that combination with a predetermined level, coupling the result of the comparison to its output, thereby collectively adjusting the amplitudes of the signals such that the combination equals the predetermined level, and where the two constituent members comprise a static and a movingmember, the moving member, traversing past the static member and also including a plurality of indices, which traverse past a plurality of index detectors included in the static member, each one of the index detectors providing an output responsive to the traversing of each one of the indices, each one of the output of the index detectors providing one of the plurality of displacement indicating signals, the signals being regularly repetitive with respect to the displacement, and evenly distributed with respect to the displacement, the combination of the signals, employed by the signal stabiliser being a summing of the signals.
According to another aspect of the present invention, there is provided an apparatus for the determination of angular displacement between two constituent members, employed as the position sensing element in a servomechanism, the two members co-operatively providing an output indicative of the displacement, the output comprising a plurality of signals, the signals posessing a combination which is independent of the displacement, the signals being coupled as an input to a signal stabiliser, the amplitudes of the signals being collectively responsive to an output of the signal stabiliser, where the signal stabiliser forms the combination of the signals and compares that combination with a predetermined level, coupling the result of that comparison to its output, thereby collectively adjusting the amplitudes of the signals such that the combination equals the predetermined level, and where the two constituent members comprises a static and a moving member, the moving member, traversing past the static member and also including a plurality of indices, which traverse past a plurality of index detectors included in the static member, each one of the index detectors providing an output responsive to the traversing of each one of the indices, each one of the outputs of the index detectors providing one of the plurality of displacement indicating signals, the signals being regularly repetitive with respect to the displacement, and evenly distributed with respect to the displacement, the combination of the signals, employed by the signal stabiliser being a summing of the signals.
According to another aspect of the present invention, there is provided an apparatus for the determination of rectilinear displacement between two constituent members, employed as the position sensing element in a servomechanism, the two members cooperatively providing an output indicative of the displacement, the output comprising a plurality of signals, the signals possessing a combination which is independent of the displacement, the signals being coupled as an input to a signal stabiliser, the amplitudes of the signals bieng collectively responsive to an output of the signal stabiliser, where the signal stabiliser forms the combination of the signals and compares that combination with a predetermined level, coupling the result of that comparison to its output, thereby collectively adjusting the amplitudes of the signals such that the combination equals the predetermined level, and where the two constituent members comprise a static and a moving member, the moving member, traversing past the static member and also including a plurality of indices, which traverse past a plurality of index detectors included in the static member, each one of the index detectors providing an output responsive to the traversing of each one of the indices, each one of the outputs of the index detectors providing one of the plurality of displacement indicating signals, the signals being regularly repetitive with respect to the displacement, and evenly distributed with respect to the displacement, the combination of the signals, employed by the signal stabiliser being a summing of the signals.
According to another aspect of the present invention, there is provided an apparatus for the determination of displacement between two constituent members, the two members cooperatively providing an output indicative of the displacement the output comprising a plurality of signals, the signals possessing a combination which is independent of the displacement, the signals being coupled as an input to a signal stabiliser, the amplitudes of the signals being collectively responsive to an output of the signal stabiliser, where #the signal stabiliser forms the combination of the signals and compares that combination with a predetermined level, coupling the result of that comparison to its output, thereby collectively adjusting the amplitudes of the signals such that the combination equals the predetermined level, the signals being regularly repetitive and evenly distributed with respect to the displacement, the combination of the signals being employed by the signal stabiliser being a summing of the signals.
According to another aspect of the present invention, there is provided an apparatus for the determination of displacement between two constituent members, the two members cooperatively providing an output indicative of the displacement, the output comprising a plurality of signals, the signals possessing a combination which is independent of the displacement, the signals being coupled as an input to a signal stabiliser, the amplitudes of the signals being collectively responsive to an output of the signal stabiliser, where the signal stabiliser forms the combination of the signals and compares that combination with a predetermined level, coupling the result of that comparison to its output, thereby collectively adjusting the amplitudes of the signals such that the combination equals the predetermined level, and where the two constituent members comprise a static and a moving member, the moving member, traversing past the static member and also including a plurality of indices, which traverse past a plurality of index detectors included in the static member, each one of the index detectors providing an output responsive to the traversing of each one of the indices, each one of the outputs of the index detectors providing one of the plurality of displacement indicating signals, the signals being regularly repetitive with respect to the displacement, and evenly distributed with respect to the displacement, the combination of the signals, employed by the signal stabiliser being a summing of the signals, the moving member, in particular, having as its indices, a corresponding plurality of regularly spaced opaque lines, with width equal to half of their repetition distance, normally disposed to the displacement and deposited onto a laminar, light transmitting slide, and the static member having a light source, giving out a light beam, responsive in its intensity to the signal stabiliser, and also having, as its index detectors, a plurality of light transducers each situated behind one out of a plurality of light transmitting masks, the masks having on them opaque lines identical to those on the slide, where the light beam, being normal to both the displacement and the slide, firstly, passes through the slide, secondly, passes through the masks, and thirdly, impinges onto the light transducers, where the intensity of the impinging light is modulated by the interaction of the slide and mask on the light beam.
According to another aspect of the present invention, there is provided an apparatus for the determination of displacement between two constituent members, for use as the position sensing element in a servomechanism, the two members co-operatively providing an output indicative of the displacement, the output comprising a plurality of signals, the signals possessing a combination which is independent of the displacement, the signals being coupled as an input to a signal stabiliser, the amplitudes of the signals being collectively responsive to an output of the signal stabiliser, where the signal stabiliser forms the combination of the signals
and compares that combination with a predetermined level, coupling the result of that comparison to its output, thereby collectively adjusting the amplitudes of the signals such that the combination equals the predetermined level, and where the two constituent members comprise a static and a moving member, the moving member, traversing past the static member and also including a plurality of indices, which traverse past a plurality of index detectors included in the static member, each one of the index detectors providing an output responsive to the traversing of each one of the indices, each one of the outputs of the index detectors providing one of the plurality of displacement indicating signals, the signals being regularly repetitive with respect to the displacement, and evenly distributed with respect to the displacement, the combination of the signals, employed by the signal stabiliser being a summing of the signals, the moving member, in particular, having as its indices, a corresponding plurality of regularly spaced opaque lines, with width equal to half of their repition distance, normally disposed to the displacement and deposited onto a laminar, light transmitting slide, and the static member having a light source, giving out a light beam, responsive in its intensity to the signal stabiliser, and also having, as its index detectors, a plurality of light transducers each situated behind one out of a plurality of light transmitting masks, the masks having on them, opaque lines identical to those on the slide, where the light beam, being normal to both the displacement and the slide, firstly, passes through the slide, secondly, passes through the masks, and thirdly, impinges onto the light transducers, where the intensity of the impinging light is modulated by the interaction of the slide and mask on the light beam.
According to another aspect of the present invention, there is provided an apparatus for the determination of angular displacement between two constituent members, for use as the position sensing element in a servomechanism, the two members co-operatively providing an output indicative of the displacement, the output comprising a plurality of signals, the signals possessing a combination which is independent of the displacement, the signals being coupled as an input to a signal stabiliser, the amplitudes of the signals being collectively responsive to an output of the signal stabiliser, where the signal stabiliser forms the combination of the signals and compares that combination with a predetermined level, coupling the result of that comparison to its output, thereby collectively adjusting the amplitudes of the signals such that the combination equals the predetermined level, and where the two constituent members comprise a static and a moving member, the moving member, traversing past the static member and also including a plurality of indices, which traverse past a plurality of index detectors included in the static member, each one of the index detectors providing an output responsive to the traversing of each one of the indices, each one of the outputs of the index detectors providing one of the plurality of displacement indicating signals, the signals being regularly repetitive with respect to the displacement, and evenly distributed with respect to the displacement, the combination of the signals, employed by the signal stabiliser being a summing of the signals, the moving member, in particular, having as its indices, a corresponding plurality of regularly spaced opaque lines, with width equal to half of their repetition distance, normally disposed to the displacement and deposited onto a laminar, light transmitting slide, and the static member having a light source, giving out a light beam, responsive in its intensity to the signal stabiliser, and also having, as its index detectors, a plurality of light transducers each situated behind one out of a plurality of light transmitting masks, the masks having on them, opaque lines identical to those on the slide, where the light beam, being normal to both the displacement and the slide, firstly, passes through the slide, secondly, passes through the masks, and thirdly, impinges onto the light transducers, where the intensity of the impinging light is modulated by the interaction of the slide and mask on the light beam.
According to another aspect of the present invention, there is provided an apparatus for the determination of rectilinear displacement between two constituent members, for use as the position sensing element in a servomechanism, the two members co-operatively providing an output indicative of the displacement, the output comprising a plurality of signals, the signals possessing a combination which is independent of the displacement, the signals being coupled as an input to a signal stabiliser, the amplitudes of the signals being collectively responsive to an output of the signal stabiliser, where the signal stabiliser forms the combination of the signals and compares that combination with a predetermined level, coupling the result of that comparison to its output, thereby collectively adjusting the amplitudes of the signals such that the combination equals the predetermined level, and where the two constituent members comprise a static and a moving member, the moving member, traversing past the static member and also including a plurality of indices, which traverse past a plurality of index detectors included in the static member, each one of the index detectors providing an output responsive to the traversing of each one of the indices, each one of the outputs of the index detectors providing one of the plurality of displacement indicating signals, the signals being regularly repetitive with respect to the displacement, and evenly distributed with respect to the displacement, the combination of the signals, employed by the signal stabiliser being a summing of the signals, the moving member, in particular, having as its indices, a corresponding plurality of regularly spaced opaque lines, with width equal to half of their repetition distance, normally disposed to the displacement and deposited onto a laminar, light transmitting slide, and the static member having a light source, giving out a light beam, responsive in its intensity to the signal stabiliser, and also having, as its index detectors, a plurality of light transducers each situated behind one out of a plurality of light transmitting masks, the masks having on them, opaque lines identical to those on the slide, where the light beam, being normal to both the displacement and the slide, firstly, passes through the slide, secondly, passes through the masks, and thirdly, impinges onto the light transducers, where the intensity of the impinging light is modulated by the interaction of the slide and mask on the light beam.
According to another aspect of the present invention, there is provided an apparatus, for use as the position sewing element in a servomechanism, for the determination of displacment between two constituent members, the two members co-operatively providing an output indicative of the displacement, the output comprising a plurality of signals, the signals possessing a combination which is independent of the displacement, the signals being coupled as an input to a signal stabiliser, the amplitude of the signals being collectively responsive to an output of the signal stabiliser, where the signal stabiliser forms the combination of the signals and compares that combination with a predetermined level, coupling the result of that comparison to its output, thereby collectively adjusting the amplitudes of the signals such that the combination equals the predetermined level, and where the signals are regularly repetitive and uniformly distributed with respect to the displacement, the combination of the signals, employed by the signal stabiliser, being a summation of the signals.
According to a last aspect of the present invention, there is provided an apparatus, used as the position sensing element in a servomechanism, for the determination of rectilinear displacement between two constituent members, the two members co-operatively providing an output indicative of the displacement, the output comprising a plurality of signals, the signals possessing a combination which is independent of the displacement, the signals being coupled as an input to a signal stabiliser, the amplitudes of the signals being collectively responsive to an output of the signal stabiliser, where the signal stabiliser forms the combination of the signals and compares that combination with a predetermined level, coupling the result of that comparison to its output, thereby collectively adjusting the amplitudes of the signals such that the combination equals the predetermined level, and where the signals are regularly repetitive and uniformly distributed with respect to the displacement, the combination of the signals, employed by the signal stabiliser, being a summation of the signals.
Claims (17)
1. An apparatus for the determination of relative displacement between two constituent members,
said two members cooperatively providing a plurality of signals indicative of said displacement,
said signals posessing a combination which is independent of said displacement,
said signal being coupled as an input to;
signal stabilising means,
said signal stabilising means providing an output to which the amplitudes of said signals are collectively responsive,
said signal stabilising means forming said combination, of said signals,
said signal stabilising means comparing the result of said combination with a predetermined level,
said signal stabilising means coupling the result of said comparison to said output,
said output collectively adjusting the amplitudes of said signals,
such that,
said combination equals said predetermined level.
2. An apparatus as recited in claim 1 employed as the position sensing element in a servomechanism.
3. An apparatus according to claim 2 wherein said displacement is angular.
4. An apparatus according to claim 2 wherein said displacement is rectilinear.
5. An apparatus according to claim 1, wherein,
said two constituent members comprise,
a static member, and
a moving member,
said moving member traversing past said static member,
said moving member including,
a plurality of indices,
said static member including,
a a plurality of index detectors,
said indices traversing adjacently to said index detectors,
each one, out of said plurality of said index detectors, individually providing an output responsive to said traversing of each one out of said plurality of indices,
said individual outputs of said index detectors each providing one out of said plurality of signals.
6. An apparatus according to claim 5 wherein,
said signals are regularly repetitive with respect to said displacement,
said signals are uniformly distributed with respect to said displacement,
said signals, individually, have a mean value with displacement which is non-zero,
and,
said combination is an addition.
7. An apparatus as recited in claim 6, employed as the position sensing element in a servomechanism.
8. An apparatus according to claim 7, wherein said displacement is angular.
9. An apparatus according to claim 7 wherein said displacement is rectilinear.
10. An apparatus according to claim 1 wherein,
said signals are regularly repetitive with respect to said displacement,
said signals are uniformly distributed with respect to said displacement,
said signals, individually, have a mean value with displacement which is non-zero,
and,
said combination is an addition.
11. An apparatus according to claim 6, wherein,
said static member includes,
light generation means,
said light generation means providing a beam of light normal to said displacement,
the intensity of said light beam being responsive to said output of said signal stabilising means,
where,
said plurality of indices are a corresponding plurality of regularly spaced opaque lines, with width equal to half of their repition distance, and disposed normally to said displacement, deposited onto a light transmitting, laminar slide whose plane is normal both to said light beam and said displacement,
and where,
said plurality of index detectors comprises,
a plurality of light transducers, and,
a a plurality of light transmitting masks,
each member of said plurality of light transducers lying behind one out of said plurality of masks,
said masks each bearing opaque lines identical to said lines on said slide,
such that,
said light beam firstly passes through said slide,
said light beam secondly passes through said masks,
said light beam, thirdly, impinges onto said light transducers,
where,
the mutual interaction of said opaque lines on said slide and said masks with said light beam, modulates the intensity of said light beam impinging onto said light transducers.
12. An apparatus as recited in claim 11, employed as the position sensing element in a servomechanism.
13. An apparatus according to claim 12, wherein said displacement is angular.
14. An apparatus according to claim 12, wherein said displacement is rectilinear.
15. An apparatus as recited in claim 10, employed as the position sensing element in a servomechanism.
16. An apparatus according to claim 15.
wherein said displacement is angular.
17. An apparatus according to claim 15, wherein said displacement is rectilinear.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7925195A GB2054135B (en) | 1979-07-19 | 1979-07-19 | Photo-electric displacement transducer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7925195A GB2054135B (en) | 1979-07-19 | 1979-07-19 | Photo-electric displacement transducer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2054135A true GB2054135A (en) | 1981-02-11 |
| GB2054135B GB2054135B (en) | 1984-03-14 |
Family
ID=10506611
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7925195A Expired GB2054135B (en) | 1979-07-19 | 1979-07-19 | Photo-electric displacement transducer |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2054135B (en) |
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0083170A1 (en) * | 1981-12-30 | 1983-07-06 | BURROUGHS CORPORATION (a Michigan corporation) | Positioning servomechanism |
| EP0104941A2 (en) * | 1982-09-27 | 1984-04-04 | Quantum Corporation | Data storage devices |
| EP0102677A3 (en) * | 1980-03-24 | 1984-04-25 | Sperry Corporation | Optical transducer means |
| FR2566896A1 (en) * | 1984-07-02 | 1986-01-03 | Aerospatiale | METHOD AND DEVICE FOR DETERMINING THE POSITION OF A MOBILE MEMBER USING ELEMENTS WITH VARIABLE OPTICAL PROPERTIES |
| GB2163847A (en) * | 1984-08-31 | 1986-03-05 | Northrop Corp | Compensation of gain temperature coefficient in an optical pick-off for an accelerometer |
| US4590527A (en) * | 1983-11-14 | 1986-05-20 | Burroughs Corporation | Positioning servomechanisms |
| FR2588653A1 (en) * | 1985-10-16 | 1987-04-17 | Pirelli Cavi Spa | POSITION OPTICAL SENSOR |
| FR2604018A1 (en) * | 1986-09-15 | 1988-03-18 | Signal Vision Sa | Method and device for luminous display of the movement of a movable object |
| EP0307130A2 (en) * | 1987-09-10 | 1989-03-15 | Canon Kabushiki Kaisha | Position control method for movable member and apparatus therefor |
| EP0336761A2 (en) * | 1988-04-07 | 1989-10-11 | Canon Kabushiki Kaisha | Position detecting device with means for switching a plurality of alternating signals having different phases |
| EP0591832A1 (en) * | 1992-09-30 | 1994-04-13 | Canon Kabushiki Kaisha | Signal processing method and displacement information measuring device |
| US5442166A (en) * | 1993-11-15 | 1995-08-15 | Hughes Aircraft Company | Linear absolute position sensor |
| US7235776B2 (en) | 2003-08-27 | 2007-06-26 | Johannes Heidenhain Gmbh | Method and device for regulating a light source of a position-measuring unit |
| CN103148779A (en) * | 2013-01-30 | 2013-06-12 | 中国科学院长春光学精密机械与物理研究所 | Adjusting device of light source in position measurement equipment |
-
1979
- 1979-07-19 GB GB7925195A patent/GB2054135B/en not_active Expired
Cited By (24)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0102677A3 (en) * | 1980-03-24 | 1984-04-25 | Sperry Corporation | Optical transducer means |
| EP0083170A1 (en) * | 1981-12-30 | 1983-07-06 | BURROUGHS CORPORATION (a Michigan corporation) | Positioning servomechanism |
| EP0104941A2 (en) * | 1982-09-27 | 1984-04-04 | Quantum Corporation | Data storage devices |
| EP0104941A3 (en) * | 1982-09-27 | 1985-11-06 | Quantum Corporation | Data storage devices |
| US4590527A (en) * | 1983-11-14 | 1986-05-20 | Burroughs Corporation | Positioning servomechanisms |
| FR2566896A1 (en) * | 1984-07-02 | 1986-01-03 | Aerospatiale | METHOD AND DEVICE FOR DETERMINING THE POSITION OF A MOBILE MEMBER USING ELEMENTS WITH VARIABLE OPTICAL PROPERTIES |
| WO1986000697A1 (en) * | 1984-07-02 | 1986-01-30 | Societe Nationale Industrielle Aerospatiale | Method and device for determining the position of a movable member by means of elements having variable optical properties |
| GB2163847A (en) * | 1984-08-31 | 1986-03-05 | Northrop Corp | Compensation of gain temperature coefficient in an optical pick-off for an accelerometer |
| FR2588653A1 (en) * | 1985-10-16 | 1987-04-17 | Pirelli Cavi Spa | POSITION OPTICAL SENSOR |
| GB2181838A (en) * | 1985-10-16 | 1987-04-29 | Pirelli Cavi Spa | Optical position sensor |
| AU593291B2 (en) * | 1985-10-16 | 1990-02-08 | Societa' Cavi Pirelli S.P.A. | Optical position sensor |
| GB2181838B (en) * | 1985-10-16 | 1989-11-22 | Pirelli Cavi Spa | Optical position sensor |
| FR2604018A1 (en) * | 1986-09-15 | 1988-03-18 | Signal Vision Sa | Method and device for luminous display of the movement of a movable object |
| EP0307130A3 (en) * | 1987-09-10 | 1989-07-26 | Canon Kabushiki Kaisha | Position control method for movable member and apparatus therefor |
| EP0307130A2 (en) * | 1987-09-10 | 1989-03-15 | Canon Kabushiki Kaisha | Position control method for movable member and apparatus therefor |
| EP0336761A2 (en) * | 1988-04-07 | 1989-10-11 | Canon Kabushiki Kaisha | Position detecting device with means for switching a plurality of alternating signals having different phases |
| EP0336761A3 (en) * | 1988-04-07 | 1990-07-18 | Canon Kabushiki Kaisha | Position detecting device for use by switching plural alternating signals having different phases from each other |
| US5067118A (en) * | 1988-04-07 | 1991-11-19 | Canon Kabushiki Kaisha | Position detecting device for use by switching plural alternating signals having different phases from each other |
| EP0591832A1 (en) * | 1992-09-30 | 1994-04-13 | Canon Kabushiki Kaisha | Signal processing method and displacement information measuring device |
| US5483059A (en) * | 1992-09-30 | 1996-01-09 | Canon Kabushiki Kaisha | Signal processing method using comparator level adjustment in a displacement measuring device |
| US5442166A (en) * | 1993-11-15 | 1995-08-15 | Hughes Aircraft Company | Linear absolute position sensor |
| US7235776B2 (en) | 2003-08-27 | 2007-06-26 | Johannes Heidenhain Gmbh | Method and device for regulating a light source of a position-measuring unit |
| CN103148779A (en) * | 2013-01-30 | 2013-06-12 | 中国科学院长春光学精密机械与物理研究所 | Adjusting device of light source in position measurement equipment |
| CN103148779B (en) * | 2013-01-30 | 2016-01-13 | 中国科学院长春光学精密机械与物理研究所 | The adjusting gear of light source in position measurement apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2054135B (en) | 1984-03-14 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19940719 |