GB1591336A

GB1591336A - Apparatus for the recording and/or reading of information on a record carrier in the form of a tape

Info

Publication number: GB1591336A
Application number: GB3546077A
Authority: GB
Original assignee: Philips Gloeilampenfabrieken NV
Current assignee: Koninklijke Philips NV
Priority date: 1976-08-27
Filing date: 1977-08-24
Publication date: 1981-06-17
Also published as: JPS623491B2; FR2366202B1; JPS5329134A; DE2638569A1; FR2366202A1; ES461876A1; IT1085368B; CA1073425A

Description

(54) APPARATUS FOR THE RECORDING AND/OR READING OF INFORMATION ON A RECORD CARRIER IN THE FORM OF A TAPE (71) We, N.V. PHILIPS GLOEILAMPEN FABRIKEN, a limited liability Company, organised and established under the laws of the Kingdom of the Netherlands, of Emmasingel 29, Eindhoven, the Netherlands, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to an apparatus for the recording and/or reading of information on a record carrier in the form of a tape by a moving recording and/or read head, comprising a supply reel for the tape, means for intermittently driving the tape past the recording and/or read head, the supply reel and the tape-driving means being located on opposite sides of the recording and/or read head in relation to the path of travel of the tape, means for subjecting the tape, at least in the region of the recording and/ or read head, to a first tension during a first period when the tape is stationary and a second, lower tension during a second period when the tape is being driven, and a braking device which is operable during the first period to prevent movement of the tape in the region of the recording and/or read head.

German Offenlegungsschrift 2,418,632 discloses a printer for electrostatic facsimile printing in which a record carrier in the form of a paper or foil tape extends over a part of the surface of a rotating recording drum. The recording drum accommodates a needle electrode which slides over the surface of the foil tape and lifts this tape during the rotation of the drum. While the needle electrode makes contact with the tape the printing of the dots of the image to be printed can take place. The tape is stationary during this period. For the printing of the next image the tape must be moved forward by a predetermined amount.

During this movement the tape is supported by an air cushion between the tape and the recording drum so that undesirable contact with the surface of the recording drum is avoided.

In order to achieve suitable charging of the dots on the tape, a given contact pressure of the electrode on the tape is required.

However, this pressure is required only when printing takes place, i.,e. in the stationary condition of the tape and not when it is being moved forward.

According to the invention there is provided an apparatus for the recording and/or reading of information on a record carrier in the form of a tape by a moving recording and/or read head, comprising a supply reel for the tape, means for intermittently driving the tape past the recording land/or read head, the supply reel and the tapedriving means being located on opposite sides of the recording and/or read head in relation to the path of travel of the tape, means for subjecting the tape, at least in the region of the recording and/or read head, to a first tension during a first period when the tape is stationary and a second, lower tension during a second period when the tape is being driven, and a braking device which is operable during the first period to prevent movement of the tape in the region of the recording and/or read head, the braking device being arranged to act on the tape at a point thereon between the supply reel and the recording and/or read head, and the tape-tensioning means comprising first and second tensioning rollers which are arranged to act on the tape under their own weight during the first and second periods respectively so as to subject the tape to the first and second tensions respectively, and of which the first roller is heavier than the second, the first roller being arranged to act on the tape at a point thereon between the recording and/or read head and the tape-driving means, and means being provided for relieving the tape of the weight of the first roller during the second period, and the second roller being arranged to act on the tape at a point thereon between the supply reel and the braking device, and means being provided which are operable during the first period to displace the second roller downwards in a loop of the tape so as to pull a given length of tape into the loop and thereby unwind a corresponding length of tape from the supply reel, and which are arranged to release the second roller during the second period so that this roller is then supported by the loop of the tape and is free to move up with the loop during the second period when the length of tape pulled into the loop is removed therefrom by the movement of the tape past the recording and/or read head.

German Offenlegungsschrift 2,345,319 discloses an apparatus in which the forward movement of a magnetic tape is achieved by detouring the tape by a given amount. During this detour the recording or the playback of magnetic data is effected by a magnetic head. After the detour the tape is held by a braking device and the detour of the tape is removed. The masses and retarding moments then required must be adapted to each other so that during the detouring of the tape the deceleration forces acting on the winding side are larger than those on the unwinding side. The forces then occurring, however, cannot be controlled, because on the one hand different frictional forces act on the tape, whilst on the other hand the removal of the detour is effected by springs which may readily start to oscillate.

The apparatus according to the invention, however, enables accurately defined tensile forces to be obtained in the region of the recording and/or read head.

In a preferred embodiment of the invention, the second tensioning roller is of hollow construction, and the means for displacing this roller downwards comprise a pin which projects horizontally and with clearance into said roller through an end thereof, and which is displaceable between two extreme positions by an electromagnet. The pin may be mounted on an arm which is pivotable between upper and lower positions by the electromagnet and which also operates the braking device. This braking device may comprise a fixed brake block and a movable brake block which is urged towards the fixed brake block by a spring and which is held away from the fixed brake block by said arm when the latter is in the upper position, so that the tape is free to be driven. The braking device may alternatively be an electromagnetic brake which is not connected to the pivotable arm but which is arranged to the stationary.

The means for relieving the tape of the weight of the first tensioning roller during the second period may comprise a rod which is suspended vertically below the first roller and at its upper end carries a stirrup in which the first roller is rotatably arranged, and two clamping members between which the rod passes and of which one is fixed and the other is movable between a first position in which the rod is free to move in the vertical direction between the clamping members so that the weight of the first roller is carried by the tape, and a second position in which the rod is clamped between the two members and the weight of the first roller is supported by these members.

An embodiment of the invention will now be described in detail with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a perspective view of an apparatus constructed in accordance with the invention, and Figure 2 is a timing diagram illustrating the operation of the apparatus shown in Figure 1.

The apparatus shown in Figure 1 is an electrostatic microprinter. The record carrier consists of a foil tape 1 which is driven in the direction of the arrow P1 by a roller 10 which is driven by an electric motor 16 and against which the tape 1 is pressed by a spring-loaded pressure roller 15. The foil tape 1 is unwound from a supply reel 13 and is guided around a number of stationary guide rollers A. In the region of the recording head, the foil tape 1 is guided around part of the cylindrical surface of a rotatable recording drum 23 by two stationary guide rollers 2 and 3. The construction of the recording drum 23 is similar to that described in German Offenlegungsschrift 2,418,632.

The image-like electrostatic charging of the foil tape in the recording area is effected by a needle electrode which is connected, via a plug connection 28, to the electronics of the printer (not shown). The recording drum 23 continuously rotates about its longitudinal axis in the operation of the printer and performs an axial movement for the recording of the various dots which form the image. In order to perform this axial movement, the recording drum is arranged on a slide 24 which can be displaced in the direction of the double arrow P4 by an electric motor 26 through a mechanism which includes a belt drive 27. The slide 24 also carries an electric motor 20 which continuously drives the recording drum 23 via a pulley 21 and belt 22.

During the recording of an image the foil tape 1 must be stationary at least in the region of the recording drum 23 and must be tensioned in that region with la defined force of, for example, 300 mN. The con tinuously rotating recording drum 23 aerodynamically produces an air film between the drum and the foil tape 1 so that if the tape is subjected to a given tension it will be maintained at a short distance from the surface of the recording drum. The image is recorded as a micro-image in lines by means of an electric control voltage which is applied in pulses to the needle electrode which contacts the foil tape 1.

When the image has been recorded the foil tape 1 must be driven though one image length. The tension in the foil tape 1 must then be less than before in order to allow the aerodynamic film to lift the foil tape away from the drum through a distance such that the tape is neither contacted by the recording drum 23 nor by the needle electrode. A tensioning force of 25 mN is sufficient for this purpose. Disturbances in the recorded image are thus precluded.

The intermittent driving of the foil tape 1, governed by the method of operation of the microprinter, is shown in the form of a diagram in Figure 2. The curves shown are given for two recording periods, each of which consists of a stationary period and a movement period. The curves show the following: Curve I: the electrostatic printing during the stationary period between instants t and t2; Curve II: the motion of an arm 6 (Figure 1) for controlling the unwinding of the foil tape 1 from the supply reel; Curve III: the actuation of a braking device 4 (Figure 1) for holding the tape 1 stationary during the stationary period; Curve IV: the energizing and de-energizing of a magnet 9 (Figure 1) for controlling the tensioning of the tape 1 during the sta tionary period; Curve V: the control of a motor 16 for driving the roller 10 during the movement period between instants t3 and t.

During the printing of an image on the foil tape 1; the foil tape 1 is held stationary by the braking device 4. This device con silts of a fixed brake block 41 and a movable brake block 42 between which the foil tape 1 is guided. The brake block 42 is urged towards the brake block 41 by a spring 43. To permit movement of the foil tape 1 the brake block 42 must be lifted against the action of the spring 43. This is effected through a pair of carriers 44 and 45 which are rigidly connected to the arm 6, which is rotatable about a pivot 61. This arm is rotatable in the direction of the arrow P5 by an electromagnet 5. At the instant t1 (Figure 2) the arm 6 is still in the upper position shown in Figure 1, in which the brake block 42 Is held away from the brake block 41 by- the carriers 44 and 45 and the foil tape 1' can be freely driven.

At the instant t1 the electromagnet 5 is energized so that the arm 6 is slowly rotated downwards about its pivot 61 (Curve II). At the start of this pivoting movement the carriers 44 and 45 release the brake block 42, which consequently presses the tape 1 against the fixed brake block 41 due to the action of the spring 43 (Curve III) to hold the tape stationary.

The tape tension of 300 mN required for the printing of an image is supplied by a tensioning roller 7 which during the period t1-t2 is freely suspended in a loop la of the tape and with its own weight produces an overall force of 600 mN in the direction of the arrow P2.

The tape drive 10, 15, 16, then being stationary, holds the foil tape 1 at the exit side of the apparatus. Half the weight of the tensioning roller 7 then acts on the portion of the tape which lies between the roller 7 and the braking device 4.

While the image is being printed on the foil tape 1, the arm 6 is slowly rotated further downwards by the electromagnet 5. A carrier pin 11 projecting horizontally from one side of the arm 6 moves down with the arm. This carrier pin 11 projects with clearance into a second tensioning roller 12 which is constructed as a hollow cylinder.

As a result of its downward movement the carrier pin 11 is forced against the inner side of the roller 12 and takes this roller down to the lower position which is denoted by a broken line in Figure 1. The roller 12 is situated in a loop ib of the tape 1, and since the tape is held on one side of this loop by the braking device 4, the forced lowering of the compensating roller 12 causes an exactly defined length of foil tape to be pulled into the loop lb at the other side thereof and a corresponding length of tape thereby unwound from the supply reel 13.

Upon completion of the printing of an image on the foil tape 1, the magnet 9 is switched on at the instant t prior to the tape-driving period t3-t4, as shown in Curve IV. The magnet 9 moves a clamping member 19, which is connected to the arma-' ture of the magnet 9, towards a rod 17 which is suspended vertically below the tensioning roller 7 and which at its upper end carries a stirrup 17a in which the roller 7 is rotatably arranged. The movable clamping member 19 clamps the rod 17 against a fixed member 18. In order to increase the frictional forces exerted by the clamping members 18 and 19,- a friction lining 8 is provided on the rod 17. As a result of the clamping of the rod 17, the tensioning roller 7 is no longer supported' by the tape 1 and hence the tensioning force P2 is removed. The roller 7 then serves as a guide roller for the duration of this tapedriving period. Approximately simultaneously with the switching on of the magnet 9, the magnet 5 is switched off. A spring 14 which was compressed by the downward movement of the arm 6 returns the arm 6 to its upper position after the switching-off of the magnet 5 (Curve II). Just before the arm 6 reaches this position the brake block 42 is lifted by the carriers 44 and 45 to release the foil tape 1. The upward movement of the arm 6 raises the carrier pin 11 (denoted by a broken line), so that the roller 12 is no longer supported by the pin and becomes suspended in the loop lb of the tape 1. The weight of the roller 12, which is lighter than the other tensioning roller 7, then acts freely on the foil tape 1. In the described embodiment, the tensioning roller 12 has a weight of 50 mN, which acts in the direction of the arrow P3. This overall weight acts on both sides of the loop ib of the foil tape 1, so that a tape tension of 25 mN prevails in the region of the recording drum 23.

After the releasing of the foil tape 1 by the braking device 4, the electric motor 16 is switched on at the instant t3 (Curve V) and the foil tape 1 is driven through one image length by the roller 10. During this movement of the tape 1 the tensioning roller is lifted to its upper position (shown in full lines in Figure 1) by the tape against the force P3. Thus, the length of tape which was taken into the loop ib by the downward movement of the roller 12 is taken out of the loop by the subsequent movement of the tape through the one image length. The displacement of the carrier pin 11 may be so proportioned that, at the end of this movement of the tape 1 and the consequent upward movement of the tensioning roller 12, the lower inner side of this roller is in contact with the carrier pin 11. This contact, however, is not essential, which means that the distance through which the carrier pin is displaced may be greater than that through which the roller 12 is lifted by the foil tape 1. The tape-tensioning force of 25 mN remains until the beginning tl of the next recording operation, which is again initiated by a recording command. Arbitrarily long intervals may be introduced at the instants tl or t3.

After the recording, the foil tape is guided through a developing station which consists of a developing chamber 29 and a supply reservoir 30. A pump 31 supplies developer liquid from the reservoir 30 to the upper part of the developing chamber via a supply duct 32. The developer liquid is sprayed onto the foil tape through two slotted spray heads. Under gravity the developer liquid flows down the foil tape and is returned to the supply reservoir 30 via a discharge duct 33.

Although in the described embodiment of the invention the recording is effected electrostatically with a needle electrode, the invention is not limited to this type of recording; for example, a rotating magnetic head could be used to record information on a magnetic tape.

WHAT WE CLAIM IS:- 1. An apparatus for the recording and/or reading of information on a record carrier in the form of a tape by a moving recording and/or read head, comprising a supply reel for the tape, means for intermittently driving the tape past the recording and/or read head, the supply reel and the tapedriving means being located on opposite sides of the recording and/or read head in relation to the path of travel of the tape, means for subjecting the tape, at least in the region of the recording and/or read' head, to a first tension during a first period when the tape is stationary and a second, lower tension during a second period when the tape is being driven, and a braking device which is operable during the first period to prevent movement of the tape in the region of the recording and/or read head, the braking device being arranged to act on 'the tape at a point thereon between the supply reel and the recording and/or read head, and the tape-tensioning means comprising first and second tensioning rollers which are arranged to act on the tape under their own weight during the first and second periods respectively so as to subject the tape to the first and second tensions respectively, and of which the first roller is heavier than the second, the first roller being arranged to act on the tape at a point thereon between the recording and/or read head and the tape-driving means, and means being provided for relieving the tape of the weight of the first roller during the second period, and the second roller being arranged to act on the tape at a point thereon between the supply reel and the braking device, and means being provided which are operable during the first period to displace the second roller downwards in a loop of the tape so as to pull a given length of tape into the loop and thereby unwind a corresponding length of tape from the supply reel, and which are arranged to release the second roller during the second period so that this roller is then supported by the loop of the tape and is free to move up with the loop during the second period when the length of tape pulled into the loop is removed therefrom by the movement of the tape past the recording and/or read head.

2. An apparatus as claimed in Claim 1, wherein the second tensioning roller is of hollow construction, and wherein the means for nisdacincr this roller downwards comprise a pin which projects horizontally and with clearance into said roller through an

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. the magnet 5 is switched off. A spring 14 which was compressed by the downward movement of the arm 6 returns the arm 6 to its upper position after the switching-off of the magnet 5 (Curve II). Just before the arm 6 reaches this position the brake block 42 is lifted by the carriers 44 and 45 to release the foil tape 1. The upward movement of the arm 6 raises the carrier pin 11 (denoted by a broken line), so that the roller 12 is no longer supported by the pin and becomes suspended in the loop lb of the tape 1. The weight of the roller 12, which is lighter than the other tensioning roller 7, then acts freely on the foil tape 1. In the described embodiment, the tensioning roller 12 has a weight of 50 mN, which acts in the direction of the arrow P3. This overall weight acts on both sides of the loop ib of the foil tape 1, so that a tape tension of 25 mN prevails in the region of the recording drum 23. After the releasing of the foil tape 1 by the braking device 4, the electric motor 16 is switched on at the instant t3 (Curve V) and the foil tape 1 is driven through one image length by the roller 10. During this movement of the tape 1 the tensioning roller is lifted to its upper position (shown in full lines in Figure 1) by the tape against the force P3. Thus, the length of tape which was taken into the loop ib by the downward movement of the roller 12 is taken out of the loop by the subsequent movement of the tape through the one image length. The displacement of the carrier pin 11 may be so proportioned that, at the end of this movement of the tape 1 and the consequent upward movement of the tensioning roller 12, the lower inner side of this roller is in contact with the carrier pin 11. This contact, however, is not essential, which means that the distance through which the carrier pin is displaced may be greater than that through which the roller 12 is lifted by the foil tape 1. The tape-tensioning force of 25 mN remains until the beginning tl of the next recording operation, which is again initiated by a recording command. Arbitrarily long intervals may be introduced at the instants tl or t3. After the recording, the foil tape is guided through a developing station which consists of a developing chamber 29 and a supply reservoir 30. A pump 31 supplies developer liquid from the reservoir 30 to the upper part of the developing chamber via a supply duct 32. The developer liquid is sprayed onto the foil tape through two slotted spray heads. Under gravity the developer liquid flows down the foil tape and is returned to the supply reservoir 30 via a discharge duct 33. Although in the described embodiment of the invention the recording is effected electrostatically with a needle electrode, the invention is not limited to this type of recording; for example, a rotating magnetic head could be used to record information on a magnetic tape. WHAT WE CLAIM IS:-

1. An apparatus for the recording and/or reading of information on a record carrier in the form of a tape by a moving recording and/or read head, comprising a supply reel for the tape, means for intermittently driving the tape past the recording and/or read head, the supply reel and the tapedriving means being located on opposite sides of the recording and/or read head in relation to the path of travel of the tape, means for subjecting the tape, at least in the region of the recording and/or read' head, to a first tension during a first period when the tape is stationary and a second, lower tension during a second period when the tape is being driven, and a braking device which is operable during the first period to prevent movement of the tape in the region of the recording and/or read head, the braking device being arranged to act on 'the tape at a point thereon between the supply reel and the recording and/or read head, and the tape-tensioning means comprising first and second tensioning rollers which are arranged to act on the tape under their own weight during the first and second periods respectively so as to subject the tape to the first and second tensions respectively, and of which the first roller is heavier than the second, the first roller being arranged to act on the tape at a point thereon between the recording and/or read head and the tape-driving means, and means being provided for relieving the tape of the weight of the first roller during the second period, and the second roller being arranged to act on the tape at a point thereon between the supply reel and the braking device, and means being provided which are operable during the first period to displace the second roller downwards in a loop of the tape so as to pull a given length of tape into the loop and thereby unwind a corresponding length of tape from the supply reel, and which are arranged to release the second roller during the second period so that this roller is then supported by the loop of the tape and is free to move up with the loop during the second period when the length of tape pulled into the loop is removed therefrom by the movement of the tape past the recording and/or read head.

end thereof and which displaceable between two extreme positions by an electromagnet.

3. An apparatus as claimed in Claim 2, wherein said pin is mounted on an arm which is pivotable between upper and lower positions by the electromagnet and which also operates the braking device.

4. An apparatus as claimed in Claim 3, wherein the braking device comprises a fixed brake block and a movable brake block which is urged towards the fixed brake block by a spring and which is held away from the fixed brake block by said arm when the latter is in the upper position so that the tape is free to be driven.

5. An apparatus as claimed in any of Claims 1 to 4, wherein the means for relieving the tape of the weight of the first tensioning roller during the second period comprise a rod which is suspended vertically below the first roller and at its upper end carries a stirrup in which the first roller is rotatably arranged, and two clamping members between which the rod passes and of which one is fixed and the other is movable between a first position in which the rod is free to move in the vertical direction between the clamping members so that the weight of the first roller is carried by the tape, and a second position in which the rod is clamped between the two members and the weight of the first roller is supported by these members.

6. An apparatus as claimed in Claim 5, wherein the rod comprises a friction lining in the region of the clamping members.

7. An apparatus substantially as hereindescribed with reference to the accompanying drawings.