BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a noble gas discharge lamp. More particularly,
the present invention relates to a noble gas discharge lamp comprising a light emitting
layer comprising an aperture inside a glass bulb, and a pair of outer electrodes in the
shape of a belt outside the glass bulb, in which the outer electrodes are improved in their
structure so as to produce a stable travel of electric discharge.
This application is based on patent application No. Hei 09-094017 filed in Japan,
the content of which is incorporated herein by reference.
Description of the Related Art
The applicants of the present invention previously proposed the noble gas
discharge lamp shown in Figures 10 and 11. In Figures 10 and 11, reference number 1
indicates a hermetic outer enclosure in the shape of a straight tube, and is comprised of a
glass bulb, for example. On the inside of the outer enclosure 1, a light emitting layer 2
is formed which is comprised of one or more kinds of fluorescent substances such as
fluorescent rare earth substances and fluorescent halorine acid salt substances. In
particular, an aperture 2a having a certain opening angle is formed to extend over the full
length of the light emitting layer 2.
The outer enclosure 1 is sealed by adhering glass plates in the shape of a disc to
the ends of the glass bulb. However, for example, the outer enclosure 1 can also be
sealed by tapering and cutting the ends of the glass bulb, while heating.
Moreover, the internal part of the outer enclosure 1 is filled with one kind of
noble gas such as xenon (Xe), krypton (Kr), neon (Ne), helium (He), and the like, or a
mixture thereof in which a metallic vapor such as mercury is not contained. Among
these noble gases, noble gas comprising xenon as a main component is preferable.
An outer laminate 3 is rolled closely into the outside of the outer enclosure 1.
The outer laminate 3 may be composed of a light transmitting sheet 4, a pair of outer
electrodes 5 and 6, terminals 51 and 61, and an adhesive layer 9.
The light transmitting sheet 4 has a length equal to a length of the outer enclosure
1, and a thickness in a range of 20 to 100 microns. This light transmitting sheet 4 have
electrical insulating properties, and may be suitably comprised of polyethylene
terephtalate (PET), however, polyester resin can be also used.
The above-mentioned pair of outer electrodes 5 and 6 are comprised of a metallic
member having a light insulating property, the appearance thereof is tape shape, and it is
adhered to one surface of the light transmitting sheet 4 so as to separate one outer
electrode 5 from the other outer electrode 6 at a certain interval.
The terminals 51 and 61 are connected electrically to the ends of the outer
electrodes 5 and 6. They are arranged at the edge of the light transmitting sheet 4 so
that the ends thereof project from the edge of the light transmitting sheet 4. The
thickness of the terminals 51 and 61 is preferably in a range of 0.1 to 0.5 mm.
The outer electrodes 5 and 6 and the terminals 51 and 61 are comprised of metals
having differing corrosion potentials; for instance, aluminum foil in the shape of a tape
is suitable for the outer electrodes 5 and 6. In addition to aluminum, nickel and other
metals which have excellent electroconductivity and light insulating properties can
comprise the outer electrodes 5 and 6. Regarding the terminals 51 and 61, copper in the
shape of a strip is suitable. However, in addition to copper, metals such as silver,
stainless steel, Cu-Ni alloy, and the like can comprise the terminals 51 and 61.
In particular, in the relationships of the widths between the outer electrodes 5 and
6 and the terminals 51 and 61, the width (w) of the outer electrodes 5 and 6, and the
width (d) of the terminals 51 and 61 preferably satisfy the formula: 0.1 w ≦ d ≦ 0.5 w.
The adhesive layer 9 has sticky properties and/or adhesive properties, and is
adhered to one surface of the light transmitting sheet 4. The adhesive layer 9 is
suitably comprised of a silicon adhesive agent; however, acryl resin adhesive agents and
the like can also be used.
Moreover, a plating layer (not shown in the Figures) is formed on the terminals
51 and 61. The plating layer is comprised of metals which are different from metals
comprising the outer electrodes 5 and 6 and the terminals 51 and 61, and of which the
corrosion potential difference is between the corrosion potential differences of the
metals comprising the outer electrodes 5 and 6 and the terminals 51 and 61. For
instance, in the case in which the outer electrodes 5 and 6 are comprised of aluminum
foil and the terminals 51 and 61 are comprised of copper; nickel and lead-tin solder can
be listed as metals suitable for comprising the plating layer.
The plating layer can be formed preferably by electroplating or electroless
plating; however, the plating layer can also be formed by an immersion or a flame spray.
The thickness of the plating layer is preferably in a range of 5 to 30 microns,
more preferably in a range of 10 to 20 microns. However, a plating layer having a
thickness outside the range can also be used.
The aforementioned outer laminate 3 is formed onto the outside of the outer
enclosure 1 so that the outer electrodes 5 and 6 are positioned between the outer
enclosure 1 and the light transmitting sheet 4. One edge 4a of the light transmitting
sheet 4 is laminated and adhered to the other edge 4b at the following second opening
portion 8. Moreover, in a condition in which the outer laminate 3 is adhered to the
outer enclosure 1, a first opening portion 7 is formed by the side portions of the outer
electrodes 5 and 6, and the second opening portion 8 is formed by the other side portions
of outer electrodes 5 and 6. The light from the light emitting layer 2 is emitted mainly
from the first opening portion 7 via the aperture 2a.
The noble gas discharge lamp comprising the above-mentioned components can
be produced by the following steps.
A water soluble fluorescent paint is made by mixing water soluble fluorescent
substances having an emission spectrum in a blue range, a green range, and a red range,
for example. Next, the light emitting layer 2 is formed by coating the water soluble
fluorescent paint on the inside of the outer enclosure 1 comprised of a glass bulb, by
drying and then firing.
The aperture 2a is formed by peeling off and by forcibly removing a part of the
light emitting layer 2, while maintaining a certain opening angle, by using a scraper (not
shown in the Figures). The obtained outer enclosure 1 is sealed and is filled with a
certain amount of noble gas such as xenon and the like.
As shown in Figures 11 and 12, the outer laminate 3 is formed by positioning one
pair of the outer electrodes 5 and 6 on the light transmitting sheet 4 so as to be disposed
with a certain space therebetween, so that the terminals 51 and 61 project out from the
edge of the outer electrodes 5 and 6, and by forming the adhesive layer 9 onto the upper
surfaces of the light transmitting sheet 4 and the outer electrodes 5 and 6.
As shown in Figure 13, the unfolding of outer laminate 3 obtained by the above-mentioned
steps is positioned on the stage 10. The outer enclosure 1 is positioned on
the outer laminate 3 so that the outer enclosure 1 is positioned on the edge 4a of the light
transmitting sheet 4, and the longitudinal axis of the outer enclosure 1 is parallel to the
longitudinal axis of the outer electrodes 5 and 6. Rollers 11 and 11 are positioned so
that the outer enclosure 1 is contacted with some pressure to the light transmitting sheet
4, while maintaining the above conditions.
While maintaining the above conditions, as shown in Figure 13, the stage 10 is
moved in the direction M, and is then moved in the direction N. Because of these
movements, the outer laminate 3 is wound around the outside of the outer enclosure 1,
and one edge 4a is overlapped on the other edge 4b of the light transmitting sheet 4, as
shown in Figure 10. Then, the noble gas discharge lamp is produced by adhering the
edges 4a and 4b of the light transmitting sheet 4 with the adhesive layer 9.
According to the noble gas discharge lamp having the above-mentioned
components, light emitted from the light emitting layer 2 is concentrated in the outer
enclosure 1, and is emitted from the outside of the noble gas discharge lamp via the first
opening portion 7 and the aperture 2a. Therefore, when the noble gas discharge lamp is
used in an office automation device such as an illumination device, the intensity of
illumination on a document being scanned can be increased. As a result, accurate
scanning of documents can be improved.
Moreover, it is anticipated that the noble gas discharge lamp will have the
following effects.
The plating layer is formed between the outer electrodes 5 and 6 and the
terminals 51 and 61; therefore, even if the outer electrodes 5 and 6 and the terminals
51 and 61 which are comprised of metals having different corrosion potential from each
other, are connected directly, generation of corrosion due to the contact of different
kinds of metal can be prevented.
In particular, when the width (w) of the outer electrodes 5 and 6 and the width
(d) of the terminals 51 and 61 are set to satisfy the following formula:
0.1 w ≦ d ≦ 0.5 w, corrosion due to contact of different kinds of metal can be
effectively prevented, in company with the existence of the plating layer. Therefore, a
stable travel of electric discharge of the noble gas discharge lamp can be maintained for
long periods.
However, when the width (d) of the terminals 51 and 61 is less than 0.1 w,
contact intensity to the outer electrodes 5 and 6 of the terminals 51 and 61 is decreased.
In contrast, when the width (d) of the terminals 51 and 61 is more than 0.5 w, in winding
the outer laminate 3 around the outside of the outer enclosure 1, the terminals 51 and 61
could not be wound around the outside of the outer enclosure 1 more easily . This
process is extremely troublesome. Therefore, it is preferable that width (w) of the outer
electrodes 5 and 6 and the width (d) of the terminals 51 and 61 satisfy the above-mentioned
formula.
Moreover, the following effects can be obtained in the process for products.
The adhesive layer 9 is formed on one surface of the light transmitting sheet 4; therefore,
the outer laminate 3 can be adhered closely to the outside of the outer enclosure 1 by a
simple step, that is, simply by rolling the outer enclosure 1 onto the outer laminate 3.
In addition, the outer electrodes 5 and 6 are positioned previously so as to be disposed at
a certain interval from each other on the light transmitting sheet 4; therefore, in adhering
the outer laminate 3 to the outer enclosure 1, it is not necessary to adjust the positioning
of the outer electrodes 5 and 6 to maintain a certain interval therebetween. Therefore,
it can be anticipated that not only will the work efficiency be greatly improved, but
automated production of the noble gas discharge lamp will also be possible. That is,
production of the noble gas discharge lamp in large quantities may be anticipated.
As shown in Figure 14, the resulting noble gas discharge lamp is switched on to
produce light by applying a high voltage of high frequency (for example, a frequency of
30 kHz and a voltage of 2500 Vo-p ) to the outer electrodes 5 and 6, from an inverter
circuit 12, via the terminals 51 and 61.
For instance, the voltage applied to the outer electrodes 5 and 6 is
approximately 2500 Vo-p in a noble gas discharge lamp which is 8 mm in external
diameter and 360 mm in total length.
Moreover, this noble gas discharge lamp is different from lamps having one
discharge along the longitudinal direction of the outer enclosure 1, such as a noble gas
discharge lamp having a hot cathode or a cold cathode. More specifically, innumerable
discharges occur between the outer electrodes 5 and 6 (discharges are generated
approximately perpendicularly to the longitudinal direction of the outer enclosure 1);
therefore, when such a light is turned on, light is emitted in a striped pattern in the
above-mentioned noble gas discharge lamp. Electric discharges in a striped pattern
cannot be confirmed under normal lighting conditions.
However, when the output electric power from the inverter circuit 12 is
decreased 10 %, for example, by a change of voltage from a power source, the electric
discharges in a striped pattern can be confirmed. Moreover, the electric discharging
positions (points) are not stable and travel in the longitudinal direction of the outer
enclosure 1, without interruption. The light emitting from aperture 2a is therefore
intermittent.
In particular, in the case of employing the noble gas discharge lamp in an
illumination device for the office equipment such as facsimile machines, image-scanners,
and the like, the light intensities at the points in the longitudinal direction of the aperture
2a change continuously. Therefore, it is possible that the scan accuracy of the
illuminated document is extremely degraded, and the quality of reproduction is also
degraded.
Summary of the Invention
It is therefore an object of the present invention to provide a noble gas discharge
lamp having a simple construction, which can produce a stable travel of electric
discharge, and lamps improving light output.
According to an aspect of the present invention, the present invention provides a
noble gas discharge lamp comprising: an outer enclosure comprising a light emitting
layer formed therein, and a pair of outer electrodes in the shape of a tape comprising a
metal, which are adhered to the total length of the outside of the outer enclosure so as to
be separated at a certain interval, and to form a first opening portion and a second
opening portion, wherein a nonlinear edge portion is formed at one side portion of one
outer electrode forming the second opening portion, and other side portion being
opposite to the nonlinear edge portion, is formed linearly.
Moreover, the nonlinear edge portion is formed at one side of one outer electrode,
in which some projections project toward the opposite electrode.
In particular when facility of production and starting characteristics of the noble
gas discharge lamps are taken into consideration, it is preferable that the projections
project toward the opposite electrode along the outside of the outer enclosure.
Moreover, dents are formed among the projections of the nonlinear edge portion.
Brief Description of the Drawings
Figure 1 is a cross-sectional diagram showing the noble gas discharge lamp of
the first embodiment of the present invention.
Figure 2 is a schematic view showing the outer enclosure and outer electrodes
shown in Figure 1.
Figure 3 is a cross-sectional diagram showing the noble gas discharge lamp of
the second embodiment of the present invention.
Figure 4 is a cross-sectional diagram showing the noble gas discharge lamp of
the third embodiment of the present invention.
Figure 5 is a cross-sectional diagram showing the noble gas discharge lamp of
the fourth embodiment of the present invention.
Figure 6 is a cross-sectional diagram showing the noble gas discharge lamp of
the fifth embodiment of the present invention.
Figure 7 is a cross-sectional diagram showing the noble gas discharge lamp of
the sixth embodiment of the present invention.
Figure 8 is a schematic view showing the outer enclosure and outer electrodes
used in the seventh embodiment of the present invention.
Figure 9 is a schematic view showing the outer enclosure and outer electrodes
used in the eighth embodiment of the present invention.
Figure 10 is a cross-sectional diagram showing a noble gas discharge lamp of
background.
Figure 11 is a schematic view showing the outer laminate shown in Figure 10.
Figure 12 is a cross-sectional diagram taken along line X-X in Figure 11.
Figure 13 is a schematic view showing the process for producing the noble gas
discharge lamp shown in Figure 10.
Figure 14 is a schematic view showing an electric circuit of a noble gas discharge
lamp.
Description of the Preferred Embodiments
A detailed explanation will now be made of the noble gas discharge lamp of the
present invention.
The first embodiment of the noble gas discharge lamp of the present invention is
explained below with reference to Figures 1 and 2. The components in Figures 1 and 2
identical to those in Figures 10 to 13 are numbered with the same reference numbers as
in Figures 10 to 13, and detailed explanations thereof will be omitted.
The characteristic components of the noble gas discharge lamp shown in Figures
1 and 2 are as follows:
The thickness of the outer enclosure 1A comprised of a glass bulb (tube) is set in a range
of 0.2 to 0.7 mm, preferably in a range of 0.4 to 0.7 mm. From among the side portions 5b and 6b of the outer electrodes 5 and 6 which form the
second portion 8, a nonlinear portion 5A in which triangles are formed is formed at only
side portion 5b. The remaining side portions 5a, 6a, and 6b of the outer electrodes 5 and 6 are formed
linearly.
The nonlinear portion 5A has a periodicity. More specifically, when the outer
diameter of the outer enclosure 1A is 8 mm, it is preferable that the width of the outer
electrode 5 including the nonlinear portion 5A be 8 mm, the pitch thereof be 4 mm, and
the height thereof (the height of the triangle) be 1.5 mm. However, the sizes of the
nonlinear portion 5A can be changed, depending on the situations of using the noble gas
discharge lamp or the illumination device comprised of the noble gas discharge lamp.
Moreover, the interval between the apexes of the nonlinear portion 5A formed at
the side portion 5b of the outer electrode 5 and the linear side portion 6b of the outer
electrode 6 is fixed over the entire outer electrodes 5 and 6. The interval between the
side portions 5a and 6a forming the first opening portion 7 is fixed over the entire outer
electrodes 5 and 6.
The outer enclosure 1A is comprised of materials having a large dielectric
constant, reliable hermetic sealing properties, and light transmitting properties.
However, it is preferable to use a lead glass having a large dielectric constant, for
example.
The thickness of the outer enclosure 1A is set in a range of 0.2 to 0.7 mm,
preferably in a range of 0.4 to 0.7 mm. Excellent productivity and light properties can
be obtained in this range.
However, when the thickness of the outer enclosure 1A is less than 0.4 mm, in
particular less than 0.2 mm, the mechanical strength of the outer enclosure 1A is
extremely decreased. Therefore, when the outer enclosures 1A are put into commercial
production, the production rate of poor quality goods (broken glass, for example)
increases. In contrast, when the thickness thereof is more than 0.7 mm, electric
discharges in a striped pattern can be confirmed. Moreover, light emission from the
aperture 2a becomes very intermittent. Therefore, it is preferable that the thickness of
the outer enclosure 1A be in that range.
The internal part of the outer enclosure 1A is filled with one kind of noble gas,
such as xenon (Xe), krypton (Kr), neon (Ne), helium (He), and the like, or a mixture
thereof. The outer enclosure 1A is filled with the noble gas under the confining
pressure being in a range of 83 to 200 Torr.
When the confining pressure is in this range, starting characteristics, and light
output (illumination intensity on the illuminated document) can be improved, and the
occurrence of intermittent illumination can be reduced. However, when the confining
pressure is less than 83 Torr, light output is not sufficiently improved. In contrast,
when the confining pressure is more than 200 Torr, not only are starting characteristics
inferior, but the electric discharges in a striped pattern are confirmed, and the light
emitted from the aperture 2a becomes intermittent. Therefore, it is preferable that the
confining pressure of the noble gas be in that range.
The light emitting layer 2 may include one or more kinds of fluorescent
substances, depending on the manner in which the noble gas discharge lamp is to be
used.
Examples of the fluorescent substance comprising the light emitting layer 2 are
fluorescent borates such as fluorescent europium activated yttrium·gallium borate, and
the like; fluorescent phosphate such as fluorescent cerium·terbium activated lanthanum
phosphate (LaPO4 : Ce,Tb), fluorescent tin activated strontium·magnesium phosphate
((SrMg)3(PO4)2 : Sn), fluorescent europium activated strontium boric phosphate (2SrO·
(P2O7·B2O3) : Eu), and the like; fluorescent europium activated yttrium
phosphovanadate (Y(PV)O4 : Eu); fluorescent cerium·terbium activated magnesium
aluminate (MgAl11O19 : Ce, Tb); fluorescent cerium·terbium activated yttrium· silicate
(Y2SiO5 : Ce, Tb); fluorescent europium activated barium·magnesium aluminate
(BaMg2Al16O27 : Eu); fluorescent europium activated yttrium oxide (Y2O3 : Eu), and the
like.
More specifically, for instance, in the case of a three-wavelength illumination
system, the light emitting layer comprises a mixture of fluorescent substances, that is,
fluorescent europium activated barium·magnesium aluminate having a blue emission
spectrum; fluorescent cerium·terbium activated lanthanum phosphate having a green
emission spectrum; and fluorescent europium activated yttrium·gallium borate having a
red emission spectrum.
The coated amount of the fluorescent substances is set in a range of 5 to 30
mg/cm2. In this range, the desired light output can be obtained. However, when the
coated amount is less than 5 mg/cm2, the light output decreases; therefore, the
illumination intensity on the illuminated document is insufficient. In contrast, when the
coated amount is more than 30 mg/cm2, a light emitting layer 2 having uniform quality
cannot be easily obtained. Therefore, the coated amount of the fluorescent substances
is preferably in this range.
In addition, the first and second opening portions 7 and 8 are formed at the
interval portions between the outer electrodes 5 and 6. The opening angle 1 of the
first opening portion 7 is larger than the opening angle 2 of the second opening portion
8.
Among the angles satisfying the above conditions, it is preferable that the
opening angle 1 of the first opening portion 7 be in the range of 60° to 90° and the
opening angle 2 of the second opening portion 8 be approximately 55°. However,
the opening angle 1 of the first opening portion 7 can be outside the range, depending
on the situation of using the noble gas discharge lamp. It is preferable that the second
opening portion 8 be narrow so as not to cause breaks in insulation; therefore, the
distance between one outer electrode 5 and the other electrode 6 in the second opening
portion 8 is preferably 2 mm or more.
Moreover, the opening angle of the aperture 2a is equivalent to the first angle 1
of the first opening portion 7, in the noble gas discharge lamp as shown in Figure 1.
In this embodiment, from among the side portions 5b and 6b of the outer
electrodes 5 and 6 which form the second opening portion 8, the nonlinear portion 5A in
which some projections project toward the opposite electrode, is formed at the side
portion 5b. More specifically, as shown in Figure 2, the nonlinear portion 5A having a
series of repeated triangles is formed at the side portion 5b of the outer electrode 5.
The side portion 6b of the outer electrode 6 is formed linearly.
Therefore, when a high voltage of high frequency is applied to the outer
electrodes 5 and 6, an electrical field is easily concentrated at the peaks of the triangles
of the nonlinear portion 5A. Then, the electrical discharges easily occur between the
nonlinear portion 5A and the linear side portion 6b. Therefore, when some electric
power input to the outer electrodes 5 and 6 is decreased by fluctuating output electric
power, the noble gas discharge lamp of this embodiment can be certainly lit.
In the case in which the nonlinear portions 5A and 5A are formed at the side
portions 5b and 6b, when the peaks of triangles of the nonlinear portions 5A and 5A
formed at the side portions 5b and 6b do not correspond to each other, it is difficult to
produce stable travel of electric discharge. Therefore, it is necessary to position the
outer electrodes 5 and 6 formed the nonlinear portions 5A and 5A with respect to each
other so as to correspond the peaks of triangles of the nonlinear portions 5A and 5A.
Therefore, the ease of production of the noble gas discharge lamp may be reduced.
However, the side portion 6b being opposite to the nonlinear portion 5A (side portion
5b), is formed linearly in this embodiment. Therefore, the positioning of the side
portion 6b and nonlinear portion 5A is not restricted, because the side portion 6b is
formed linearly. As a result, assembly of the noble gas discharge lamp can be
improved.
In addition, the thickness of the outer enclosure 1A is in a range of 0.2 to 0.7 mm.
Therefore, in the case that the thickness of the outer enclosure 1A is at the top of this
range, when a high voltage of high frequency is applied to the outer electrodes 5 and 6,
intermittent illumination easily occurs, depending on the increase of voltage to the outer
enclosure 1A caused by increase of resistive components. However, even if the outer
enclosure 1A is at the top of that range, intermittent illumination can be effectively
prevented by the thickness of the outer enclosure 1A being in that range, in company
with the existence of the nonlinear portion 5A at only side portion 5b of the outer
electrode 5. In addition, light output from the first opening portion 7 via the aperture
2a can be effectively improved.
Moreover, the nonlinear portion 5A having triangles is formed at the side portion
5b from among the side portions 5b and 6b of the outer electrodes 5 and 6 which form
the second portion 8; however, the side portions 5a and 6a of the outer electrodes 5 and 6
forming the first opening portion 7 are formed linearly (this shape does not influence
light emission). Therefore, even when the noble gas discharge lamp of this
embodiment is used in an illumination device, illumination of a document can be
approximately uniform without further measures being taken. As a result, the precision
of scanning of an illuminated document can be improved by simple components.
In particular, when the confining pressure of noble gas is high, light output
increases, but the starting characteristics of the noble gas discharge lamp are degraded.
However, even if the confining pressure of the noble gas is set to 200 Torr, starting
characteristics of a practical level can be obtained, by forming the nonlinear portion 5A
in a series of repeated triangles at the side portion 5b of the outer electrode 5.
Moreover, occurrence of intermittent illumination is effectively prevented, and the light
output can be improved. Therefore, when the noble gas discharge lamp of this
embodiment is used in an illumination device, stable travel of electric discharge can be
obtained, and the illumination intensity on the illuminated document can be increased;
therefore, the precision of scanning of an illuminated document can be improved.
When the coated amount of the fluorescent substance is in a range of 5 to 30
mg/cm2; the light output from the first opening portion 7 via the aperture 2a can be
effectively improved by setting the thickness of the outer enclosure 1A to a range of 0.2
to 0.7 mm, in company with setting the confining pressure of noble gas in a range of 83
to 200 Torr.
In particular, the above-mentioned range of the coated amount of the fluorescent
substances is 2 to 10 times as much as the amount of the fluorescent substances
employed in ordinary fluorescent lamps for illumination. It is believed that the coated
amount is not preferable for ordinary fluorescent lamps for illumination. However, the
light output is effectively increased in the noble gas discharge lamp of the embodiment.
A cause of this phenomena is not clear; however, it may be believed that this phenomena
is characteristic of a noble gas discharge lamp in which innumerable discharges are
formed between the outer electrodes 5 and 6 (approximately perpendicular to the
longitudinal direction of the outer enclosure 1A); therefore, a striped pattern is produced.
When the thickness of the outer enclosure 1A is in that range, the shapes of the
outer electrodes 5 and 6 are formed as described above, and the coated amount of the
fluorescent substances and the confining pressure of the noble gas are preferably set in
those ranges, in addition to set the opening angle 1 of the first opening portion 7 in a
range of 60 to 90°, the light output emitted from the first opening portion 7 can be
effectively increased.
Under these conditions, the leakage of light from the second portion 8 is
prevented, and light output emitted from the first opening portion 7 can be more
effectively increased by setting the size of the second portion 8, that is, the interval
between the peak of the nonlinear portion 5A and the side portion 6b, to approximately 2
mm.
Figure 3 shows the second embodiment of the present invention, and the basic
components of the noble gas discharge lamp shown in Figure 3 are the same as those of
the noble gas discharge lamp shown in Figure 1.
However, they differ in the following point:
The opening angle 3 of the aperture 2a formed in the inside of the outer enclosure 1A at
the position corresponding to the first opening portion 7, is larger than the opening angle
1 of the first opening portion 7.
The opening angle 3 of the aperture 2a is set in a range of 70° to 110° , for
example; however, the angle 3 can be changed depending on the situation or the object
of using the noble gas discharge lamp.
Moreover, it is preferable that the opening angle 1 of the first opening portion 7
and the opening angle 2 of the second opening portion 8 satisfy the relationship of
1 > 2 in this embodiment.
In this embodiment, in winding the outer laminate 3 onto the outside of the outer
enclosure 1A, even if the center of the first opening portion 7 is a little off-center with
respect to the center of the aperture 2a, a discrepancy of the optical axis of the light
emitted from the first opening portion 7 can be mitigated. Therefore, it is possible to
obtain full scanning accuracy when the noble gas discharge lamp of the second
embodiment is used to an illumination device.
Figure 4 shows the third embodiment of the present invention, and the basic
components of the noble gas discharge lamp shown in Figure 4 are the same as those of
the noble gas discharge lamp shown in Figure 1.
However, they differ in the following point:
One edge 4a and the outer edge 4b of the light transmitting sheet 4 are laminated to each
other on the outer electrode 5, and they are melted and adhered by ultrasonic waves.
In this embodiment, the laminated portions 4a and 4b are melted and adhered by
ultrasonic waves on the outside of the outer electrode 5; therefore, an oscillation of
ultrasonic waves applying the light emitting layer 2 positioning inside of the outer
electrode 1A is relieved. In comparing the noble gas discharge lamps of the first and
the second embodiments, the oscillation of ultrasonic waves applying the light emitting
layer 2 positioning inside of the outer electrode 1A is relieved. As a result, a peeling
off of the light emitting layer 2 from the outer enclosure 1A is substantially prevented,
and light output can be improved.
Moreover, in the above embodiment, the laminated portions 4a and 4b of the
light transmitting sheet 4 are melted and adhered by ultrasonic waves; however,
adhesion by an adhesive agent, by heat, or simultaneous use of both may also be
employed.
Figure 5 shows the fourth embodiment of the present invention, and the basic
components of the noble gas discharge lamp shown in Figure 5 are the same as those of
the noble gas discharge lamp shown in Figure 1.
However, they differ in the following point:
A pair of the outer electrodes 5 and 6 is adhered to the outside of the outer enclosure 1A
by using the adhesive layer; then a light transmitting sheet 4A comprising PET resin and
the like, for example, is wound and adhered on the outside of the outer enclosure 1A so
as to cover the outer enclosures 5 and 6.
In this embodiment, the electrical insulating ability between the outer electrodes
5 and 6 can be improved by forming an insulating coating having light transmitting
properties, which is comprised of silicon varnish, to the outside of the outer enclosure
1A, before winding the light transmitting sheet 4A onto the outside of the outer
enclosure 1A.
Figure 6 shows the fifth embodiment of the present invention, and the basic
components of the noble gas discharge lamp shown in Figure 6 are the same as those of
the noble gas discharge lamp shown in Figure 1.
However, they differ in the following point:
After a pair of outer electrodes 5 and 6 are adhered to the outside of the outer enclosure
1A using the adhesive layer, a protective tube 13 comprising thermal shrinking resin,
such as PET resin and the like, is covered thereon and shrunk with heat so that the outer
electrodes 5 and 6 are covered with the protective tube 13.
Moreover, after the protective tube 13 is fit to the outside of the outer enclosure
1A, the protective tube 13 can be forcibly contacted to the outside of the outer enclosure
1A by heating them to approximately 150 to 200°C, and the protective tube 13 is made
to shrink by heat.
Compared to the above-mentioned embodiments, manufacturing and working
efficiency in this embodiment are not as good. However, because the adhesive layer is
not used, erosion does not occur due to the reaction between the material comprising the
terminals 51 and 61 and the adhesive composition comprising the adhesive layer.
Therefore, stable travel conditions in the noble gas discharge lamp can be maintained for
long periods. In addition, the joint portion is not formed in the protective tube 13;
therefore, the peeling off of a laminated portion can be prevented as the peeling off of
the light transmitting sheet 4 can be prevented in the third embodiment.
In particular, the insulating ability between the outer electrodes 5 and 6 can be
improved more effectively by forming an insulating coating having light transmitting
properties, which is comprised of silicon varnish, to the outside of the outer enclosure
1A, before covering the protective tube 13 over the outside of the outer enclosure 1A.
Figure 7 shows the sixth embodiment of the present invention, and the basic
components of the noble gas discharge lamp shown in Figure 7 are the same as those of
the noble gas discharge lamp shown in Figure 1.
However, they differ in the following point:
After fitting a protective tube 13 over the outside of the outer laminate 3, which is
comprised of thermal shrinking resins, such as PET resin, and the like, the protective
tube 13 is made to shrink with heat.
Moreover, after the protective tube 13 is fit over the outside of the outer laminate
3, the protective tube 13 can be contacted forcibly to the outside of the light transmitting
sheet 4 by heating them to approximately 150°C to 200°C, and the protective tube 13 is
made to shrink by heat.
In this embodiment, even if the noble gas discharge lamp is used under extreme
conditions, or in situations requiring high safety standards, products having high quality
can be produced by covering the outer laminate 3 with protective tube 13 having high
heat-resistance and light transmitting properties.
In particular, the characteristic structure of this embodiment can be applied to the
noble gas discharge lamps shown in Figures 3 to 6.
Moreover, the electrical insulating material such as the light transmitting sheet 4
and 4A and the protective tube 13, may be omitted in the aforementioned embodiments.
In the following, preferred embodiments of the nonlinear portion will be
explained. As described above, the nonlinear portion is formed at one side portion
forming the second opening 8, in which some projections project toward the opposite
electrode. Among many possible kinds of the nonlinear portions, the nonlinear
portions shown in Figures 8 and 9 are preferable.
Figure 8 shows the seventh embodiment of the present invention, and shows
unfolding of outer enclosure 1A. The basic components of the noble gas discharge
lamp shown in Figure 8 are the same as those of the noble gas discharge lamp shown in
Figure 1.
However, they differ in the following points:
The nonlinear portion 5B is formed at only side portion 5b from among the side portions
5b and 6b forming the second opening portion 8. The nonlinear portion 5B is in a wave
shape, such as a series of repeated semicircles. The side portion 6b being opposite to the side portion 5b, that is, the nonlinear portion
5B, is formed linearly.
Moreover, the remaining side portions 5a, 6a, and 6b beside the side portion 5b
are entirely formed linearly.
In this embodiment, when a high voltage of high frequency is applied to the outer
electrodes 5 and 6, discharges occur between the nonlinear portion 5B (side portion 5b)
and the side portion 6b linearly; however, the positioning of the outer electrodes 5 and 6
is not restricted, because the side portion 6b is formed linearly. Therefore, assembly of
the noble gas discharge lamp can be improved.
Figure 9 shows the eighth embodiment of the present invention, and shows
unfolding of outer enclosure 1A. The basic components of the noble gas discharge
lamp shown in Figure 9 are the same as those of the noble gas discharge lamp shown in
Figure 1.
However, they differ in the following points:
The nonlinear portion 5C is formed at only the side portion 5b from among side portions
5b and 6b (they form the second opening portion 8). The nonlinear portion 5C is in a
series of repeated polygons, such as rectangles or trapezoids.
The side portion 6b, opposite to the nonlinear portion 5 C (side portion 5b), is
formed linearly.
Moreover, the remaining side portions 5a, 6a, and 6b of the outer electrodes 5
and 6 beside the side portion 5b of the outer electrode 5 are formed linearly.
In particular, the outer electrodes 5 and 6 having the above-mentioned nonlinear
portions 5B and 5C can be applied to the noble gas discharge lamps shown in Figures 1
to 7 in suitable combinations.
Moreover, the pitch and the height of the nonlinear portions can be modified,
depending on the size of the noble gas discharge lamp.
Experimental Examples
The present invention will now be explained using Experimental Examples.
Experimental Example 1
The fluorescent water-soluble coating solution containing fluorescent cerium·terbium
activated yttrium· silicate (Y2SiO5 : Ce, Tb) having an emission spectrum in
yellow-green wavelengths was obtained.
Next, the light emitting layer 2 was formed by coating the obtained fluorescent
water-soluble coating solution on the inside of the outer enclosure 1A comprised of lead
glass, which was 8 mm in external diameter, 0.5 mm in thickness, and 360 mm in length.
Moreover, the coated amount of the fluorescent water-soluble coating solution was 15
mg/cm2.
Then, the aperture 2a having 75° in the opening angle 3 was obtained by
forcibly peeling off a part of the obtained light emitting layer 2 using a scraper.
The outer enclosure 1A was sealed, and filled with xenon gas at a confining
pressure being varied in a range of 70 to 230 Torr.
Then, the noble gas discharge lamps of this Experimental Example were
produced by the same steps shown in Figures 13. Moreover, a pair of the outer
electrodes 5 and 6 was comprised of aluminum foil in the shape of a tape 8 mm in width.
As shown in Figure 2, the nonlinear portion 5A was formed at only one side portion 5b
of the outer electrode 5 forming the second opening portion 8, in which triangles 4 mm
in pitch and 1.5 mm in peak height were formed. The side portion 6b being opposite to
the nonlinear portion 5A (side portion 5b) is formed linearly.
Next, the following measurement was carried out on the noble gas discharge lamps
obtained in this Experimental Example.
(1) The electrical discharge occurring voltage (starting voltage)
The obtained noble gas discharge lamps were incorporated in an electric circuit as
shown in Figure 14, and the output voltage (frequency fixed at 30 kHz, voltage
2500 V
o-p) of the
inverter circuit 12 were gradually increased. Then, the voltages at
which discharge occurred (starting voltages) were measured in which the intermittent
illumination was not confirmed. The result of this measurement was shown in the
following Table 1.
Confining Pressure of Xenon Gas (Torr) | Starting Voltages (V) |
70 | 1750 |
83 | 2000 |
90 | 2000 |
100 | 2000 |
110 | 2250 |
120 | 2250 |
150 | 2250 |
200 | 2250 |
210 | 2500 |
230 | 2500 |
As shown in Table 1, the following points were clear.
When the confining pressure of xenon gas is 200 Torr or less, even when the
output voltage of the inverter circuit 12 was set to 90 % of a fixed voltage (2500 Vo-p),
the intermittent illumination cannot be confirmed, and stable travel of electric discharge
can be obtained after the lamps are lit. Compared with the conventional noble gas
discharge lamp does not comprise the nonlinear portion 5A, the starting voltage in a
range of 300 to 600 V can be decreased in the noble gas discharge lamps of this
Experimental Example.
When the confining pressure is 83 Torr or greater in the conventional noble gas
discharge lamp, the intermittent illumination can be confirmed. In addition, when the
confining pressure reaches 100 Torr, the conventional noble gas discharge lamp cannot
be used in practice without difficulty.
In the case of more than 200 Torr, specifically 210 Torr and 230 Torr, the lamps
can be lit with a fixed voltage (2500 Vo-p); however, start-up is not assured when the
input power was decreased.
Moreover, the following measurements were carried out for the noble gas
discharge lamps obtained in this Experimental Example.
(1) Illumination intensity of the document
The obtained noble gas discharge lamps were incorporated in an electric circuit as
shown in Figure 14, and the output voltage (frequency fixed at 30 kHz) of the inverter
circuit 12 was set to 90 % of a fixed voltage (2500 Vo-p). In these conditions, the
illumination intensities on the document were measured at a point 8 mm away from the
outer enclosure 1A. The results were shown in the following Table 2.
(2) Occurrence of intermittent illumination
The obtained noble gas discharge lamps were incorporated in an electric circuit as
shown in Figure 14, and the output voltage (frequency fixed at 30 kHz) of the inverter
circuit 12 was set to 90 % of a fixed voltage (2500 Vo-p). In these conditions, the
occurrence of intermittent illumination was evaluated at a point 8 mm away from the
outer enclosure. The results were shown in the following Table 2.
In Table 2, ○ means that intermittent illumination did not occur, ▵ means
that some intermittent illumination did occur, but the noble gas discharge lamp can be
used in practice without difficulty, and X means that intermittent illumination did
occur, and the noble gas discharge lamp cannot be used in practice without difficulty.
Confining Pressure of Xenon Gas (Torr) | Illumination intensity on the document (Lx) | Occurrence of intermittent illumination |
70 | 13000 | ○ |
83 | 15000 | ○ |
90 | 16000 | ○ |
100 | 16500 | ○ |
110 | 17000 | ○ |
120 | 17500 | ○ |
150 | 19000 | ○ |
200 | 19500 | ▵ |
210 | (20000) | X |
230 | (21000) | X |
As shown in Table 2, the following points were clear.
When the confining pressure of xenon gas is 150 Torr or less, stable travel of
electric discharge without occurrence of intermittent illumination can be obtained.
When the confining pressure of xenon gas is 200 Torr, some intermittent illuminations
did occur, but the noble gas discharge lamp can be used in practice without difficulty.
However, in the case the pressure being more than 200 Torr, specifically 210 Torr and
230 Torr, the significant intermittent illumination occurs. Therefore, it is confirmed
that it is difficult to use the noble gas discharge lamps in an illumination device because
the scanning precision of an illuminated document is degraded.
Moreover, the illumination intensity on the illuminated document increases,
depending on an increase of the confining pressure of xenon gas; however, a stable
illumination intensity without occurrence of intermittent illumination can be obtained
when the confining pressure of xenon gas is in a range of 200 Torr or less.
Therefore, it is clear from Table 2 that the confining pressure of noble gas is
suitable in a range of 83 to 200 Torr.
Experimental Example 2
Noble gas discharge lamps were produced in the same way as in Experimental
Example 1. However, the confining pressure of xenon gas was fixed at 120 Torr, and
the thickness of the outer enclosure 1A was varied in a range of 0.18 to 0.8 mm as shown
in the following Table 3.
Next, the following measurements were carried out for the noble gas discharge
lamps obtained in this Experimental Example.
(1) Occurrence of intermittent illumination
The obtained noble gas discharge lamps were incorporated in an electric circuit as
shown in Figure 14, and the output voltage (frequency fixed at 30 kHz) of the inverter
circuit 12 was set to 90 % of a fixed voltage (2500 Vo-p). In these conditions, the
occurrence of intermittent illumination was evaluated at a point 8 mm away from the
outer enclosure. The results were shown in the following Table 3.
In Table 3, ○ means that intermittent illumination did not occur, ▵ means
that some intermittent illumination did occur, but the noble gas discharge lamp can be
used in practice, and X means that intermittent illumination did occur, and the noble
gas discharge lamp cannot be used in practice without difficulty.
(2) Presence of damage in producing steps (Strength)
In production steps, the presence of damage in the outer enclosures of the obtained noble
gas discharge lamps was evaluated.
In Table 3, ○ means that damage to the outer enclosure was not observed, and
the strength of the outer enclosure is sufficient; ▵ means that some damage was
observed in the outer enclosure, but the noble gas discharge lamps comprising the outer
enclosures can be used in practice; and X means that serious damage to the outer
enclosure was observed and the strength of the outer enclosure meant the produced
lamps would be difficult to use.
Thickness of the outer enclosure (mm) | Occurrence of intermittent illumination | Strength |
0.18 | ○ | X |
0.2 | ○ | ▵ |
0.25 | ○ | ▵ |
0.4 | ○ | ○ |
0.5 | ○ | ○ |
0.6 | ○ | ○ |
0.7 | ▵ | ○ |
0.8 | X | ○ |
As shown in Table 3, the following points were clear.
When the thickness of the outer enclosure 1A is in a range of 0.18 to 0.6 mm, the
occurrence of intermittent illumination cannot be confirmed, even when the input to the
outer electrodes 5 and 6 is low.
When the thickness is 0.7 mm, some intermittent illumination was confirmed;
however, the noble gas discharge lamp can be used in practice without difficulty.
However, when the thickness is 0.8 mm, significant intermittent illumination was
confirmed, and the effects obtained by forming the nonlinear portion 5A were decreased.
Moreover, when the thickness of the outer enclosure 1A is 0.4 mm or greater,
damage cannot be confirmed in the production.
When the thickness is less than 0.4 mm, especially 0.25 mm and 0.2 mm,
damage in the production was observed. In particular, when the thickness is 0.18 mm,
damage such as cracks suddenly increases; therefore, it is confirmed that mechanical
strength is low, and they are unsuitable for producing in large quantities.
Therefore, as shown in Table 3, the thickness of the outer enclosure is preferably
in a range of 0.2 to 0.7 mm, more preferably in a range of 0.4 to 0.7 mm.