JP2004228657A - Electric discharge light emitting device and contact image sensor using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized electric discharge light emitting device for preventing exfoliation of an electrode pad due to overheat by soldering and having a high inter-electrode withstanding voltage characteristic and to provide a contact image sensor using the electric discharge light emitting device. <P>SOLUTION: In the electric discharge light emitting device for forming a discharge space by sealing a part between a first board and a second board placed opposedly to the first board, first and second electrode pads respectively connected to a first electrode placed in the discharge space on the first board and a second electrode placed on the second board are respectively provided to an end of the first board in its length direction and a coating layer for coating a circumferential edge of the electrode pads is provided onto the first board and the electrode pads. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a discharge light emitting device that emits light by discharge between electrodes in a discharge space filled with a discharge gas such as xenon, and a contact image sensor using the discharge light emitting device as a light source for document irradiation.
[0002]
[Prior art]
In recent years, it has been proposed to use a discharge light emitting device using a discharge gas such as xenon as a light source for a contact image sensor. Such a discharge light emitting device has a technical advantage that the luminance distribution is more uniform than other light sources such as a light emitting diode array and the device life is longer.
[0003]
On the other hand, since a high alternating voltage (for example, a voltage of about 1,000 Vrms) is applied between the electrodes of the discharge tube in which the discharge gas such as xenon is sealed, a high withstand voltage characteristic is provided between the electrodes. Required. Further, a harness wire for supplying an AC high voltage is also required to have high withstand voltage characteristics, and the wire diameter of the harness wire tends to be large.
[0004]
[Patent Document 1]
JP 2001-229881 A (page 2, page 4 to page 6, FIGS. 1 to 3)
[0005]
[Problems to be solved by the invention]
However, there is a strong demand for downsizing such a discharge light emitting device, and it is necessary to make the electrode pad portion for connecting a harness wire small, and when a harness wire is connected to such an electrode pad portion by soldering. In addition, there is a problem that the electrode pad is separated from the substrate due to overheating during soldering.
[0006]
In addition, there is also a problem that the withstand voltage characteristic between the electrodes is reduced due to the reduction of the area where the electrode pad portion is provided due to the miniaturization of the device.
[0007]
The present invention has been made in order to solve the above-described problems, while improving the adhesive strength of the electrode pad portion, preventing peeling of the electrode pad due to overheating when the harness wire is soldered to the electrode pad portion, and It is an object of the present invention to provide a novel discharge light emitting device which is small and has high withstand voltage between electrodes.
[0008]
Another object of the present invention is to provide a novel contact image sensor that can realize high-precision reading by using such a discharge light emitting device as a light source, and that is compact and has high reliability.
[0009]
[Means for Solving the Problems]
The discharge light emitting device according to the first aspect of the present invention is a discharge light emitting device, comprising: a first substrate, a second substrate opposed to the first substrate, and a discharge between the first substrate and the second substrate. A sealing portion forming a space, a first electrode provided in the discharge space on the first substrate, a dielectric layer provided in the discharge space on the first electrode, A first phosphor layer provided in the discharge space on the body layer, a second phosphor layer provided in the discharge space on the second substrate, and an opposite of the second phosphor layer A second electrode provided on the second substrate on the side, an inclined portion formed on the second substrate for outputting light generated in the discharge space to the outside, and a longitudinal portion of the first substrate. First and second electrode pads provided at the ends in the direction and connected to the first and second electrodes, respectively; Provided on the first substrate and the electrode pad portions on, in which a coating layer covering the periphery of the electrode pad portions.
[0010]
According to a second aspect of the present invention, in the discharge light emitting device, the coating layer is a dielectric layer formed by the same process as the dielectric layer formed on the first substrate.
[0011]
According to a third aspect of the present invention, in the discharge light emitting device, the dielectric layer is formed of glass containing BiO ₂ , ZnO or B ₂ O ₃ as a main component.
[0012]
According to a fourth aspect of the present invention, in the discharge light emitting device, the dielectric layer is formed of a heat-resistant insulating tape made of a polyimide resin.
[0013]
According to a fifth aspect of the present invention, there is provided a discharge light emitting device, wherein a partition is provided between the first and second electrode pads.
[0014]
According to a sixth aspect of the present invention, in the discharge light emitting device, a tip portion of the first electrode pad portion is formed in a semicircular shape having a half of the line width.
[0015]
In a discharge light emitting device according to a seventh aspect of the present invention, the first electrode is made of Ag, Cu or Al.
[0016]
An image sensor according to an eighth aspect of the present invention includes the discharge light emitting device according to any one of the first to sixth aspects.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. 1 (a) and 1 (b). 1A is a sectional view showing the configuration of the discharge light emitting device according to the first embodiment, and FIG. 1B is a partial plan view of the vicinity of an end of the discharge light emitting device shown in FIG. . 1A and 1B, reference numeral 1 denotes a discharge light emitting device, 2 denotes a first substrate made of a transparent member such as a plate-like glass, and 3 denotes a first substrate formed on the first substrate 2. The electrodes 3a are electrode pad portions provided on the first substrate 2 at the longitudinal ends of the first substrate 2, and 4 are all portions of the first electrodes 3 in the discharge space 10. In other words, a first dielectric layer (insulating layer) 4a formed on the first substrate 2 so as to cover except for a part thereof is a tip of an electrode pad portion 3a electrically connected to the first electrode 3. A dielectric layer (insulating layer) formed at the same time as the dielectric layer 4 on the first substrate 2 so as to cover the edge portion, and a recess 6 having a planar opposed portion 6a and an inclined portion 6b is provided. A second member made of a transparent member such as glass which forms a discharge space 10 by the concave container structure in a state where the second member is disposed on the substrate 2 of FIG. It is a substrate.
[0018]
Reference numeral 7 denotes a second electrode provided on the second substrate 6 on the opposite side of the opposing portion 6a forming the discharge space 10, and is disposed substantially in parallel with the first electrode 3 and 7a is a second electrode. An electrode pad portion electrically connected to the electrode 7. The second electrode 7 can be formed by an electrode pattern of Ag, Cu or Al like the first electrode 3, but a metal tape having an electrode function such as Cu or Al is formed on the second substrate 6. It may be formed by pasting, and can have a similar function.
[0019]
As shown in FIG. 1A, the electrode pad portion 3a and the electrode pad portion 7a are provided apart from each other in the direction perpendicular to the longitudinal direction of the first substrate 2, and the electrode pad portion 3a and the electrode pad portion 7a are provided on the first substrate 2 therebetween. The electrode spacing wall 6c is provided for the purpose of improving withstand voltage characteristics. Further, since the first electrode 3 and the second electrode 7 are provided so as to face each other, the electrode shape of the portion connected to the electrode pad portion 3a and the electrode pad portion 7a is the electrode pad portion 3a and the electrode Each has a pattern shape bent so as to be connected to the pad portion 7a.
[0020]
Reference numeral 8 denotes a sealing layer formed of a glass layer (a glass having a low softening point) formed by melting a glass frit, and adheres the first substrate 2 and the second substrate 6 to form a discharge space 9. Has formed. The discharge space 9 is filled with a rare gas such as neon or xenon as a simple substance or a mixed gas. Reference numerals 5 and 10 denote first and second phosphor layers. In the discharge space 9, the first phosphor layer is on the first electrode 2 and the dielectric layer 4, and the second phosphor layer is on the second On the opposing portions 6 a of the substrate 6. The thicknesses of the first phosphor layer 5 and the second phosphor layer 10 need not be the same. It is desirable that the dielectric layer 4 be provided widely so that the discharge space 9 is formed in a region where the dielectric layer 4 is provided.
[0021]
The inclined portion 6b of the second substrate 6 is a portion for outputting the light generated in the discharge space 9 to the outside, and is formed so as to make an angle of approximately 45 ° with the facing portion 6a of the second substrate 6. ing. This angle is provided so that the center of the light amount distribution of the light source when incorporated into the contact image sensor described later is adjusted to the irradiation point on the document surface, and corresponds to the distance from the inclined portion 6a to the irradiation point. Provide an appropriate angle of 30 ° or more, including °. This enables irradiation in an oblique direction when the discharge light emitting device 1 as shown in FIG. 1 is incorporated in a contact image sensor.
[0022]
In addition, as shown in FIG. 1A, the substrate thickness of the discharge inclined portion 6 is made thinner than other substrate portions, in order to reduce attenuation of the discharge light when transmitted through the substrate. The reason why the space 9 has a structure that is widened on the side of the inclined portion 6b is to efficiently discharge the discharge light generated in the discharge space 9 to the outside from the inclined portion 6b.
[0023]
The phosphor layer 5 has a thickness of about 40 μm, and is of a reflection type so that maximum light emission can be obtained on the surface. That is, the relationship between the thickness of the phosphor layer 5 and the luminous intensity generally increases as the thickness of the phosphor layer 5 increases, and when the thickness is 40 μm or more, the luminous intensity substantially saturates with respect to the change in film thickness. The structure is such that the light emission intensity is small with respect to the thickness change and a uniform light emission distribution can be obtained in the device. Therefore, the thickness of the phosphor layer 5 is desirably in the range of 40 μm to 60 μm in consideration of a change in light emission intensity with respect to a change in the thickness of the phosphor layer 5, a material amount, a man-hour for forming, and the like.
[0024]
Next, the connection configuration of the harness line lead-out portion formed on the first substrate 2 will be described. As shown in FIG. 1 (b), on the longitudinal end of the first substrate 2, a harness line leading electrode pad 3 a of the first electrode 3 and a harness line leading electrode pad of the second electrode 7 are provided. 7a are provided, and the core wire 11 of the harness wire 10 is connected to the electrode pad 3a and the electrode pad 7a by the solder 12, respectively. The harness line 10 is connected to a high-voltage power supply (not shown) and supplies an AC high voltage (for example, a voltage of about 1,000 Vrms) to the electrode pads 3a and 7a.
[0025]
An electrode pad portion 3a, which is a connection portion between the harness wire 10 and the first electrode 3, is provided at the tip end thereof by a dielectric layer 4a formed simultaneously of the same material as the dielectric layer 4, specifically, the first substrate. 2 covers the peripheral portion of the electrode pad portion 3a on the end side, and by providing such a coating layer made of the dielectric layer 4a, the electrode pad due to overheating when the harness wire 10 is soldered by the solder 12 The separation of the portion 3a from the first substrate 2 is prevented.
[0026]
The dielectric layer 4a is formed simultaneously with the same material as the dielectric layer 4 and is made of a heat-resistant insulating tape made of glass or polyimide resin containing BiO ₂ , ZnO or B ₂ O ₃ as a main component. Formed by
[0027]
Here, a change in adhesion strength when the tip of the electrode pad 3a is covered with the dielectric layer 4a will be described. FIG. 2 shows a comparison between the conventional product (the electrode pad 3a is not covered with the dielectric layer 4a) and the product of the present invention shown in FIG. 1 (the tip of the electrode pad 3a is covered with the dielectric layer 4a). FIG. 7 is a measurement diagram of the adhesion strength showing the measurement results of the adhesion strength of the electrode pad portion 3a in FIG. In the measurement of the adhesion strength, the harness wire 10 shown in FIG. 1B was pulled right above, and the tensile strength when the electrode pad portion 3a was peeled off from the first substrate 2 was measured by a tension gauge. . As shown in FIG. 2, the discharge light-emitting device according to the first embodiment (invention in FIG. 2) has about twice or more adhesion strength as compared with the conventional product (conventional product in FIG. 2). I can ask.
[0028]
As described above, in the discharge light emitting device according to the first embodiment, the coating layer covering the peripheral portion of the electrode pad 3a of the electrode 3, that is, the dielectric layer 4a is the same as the dielectric layer 4 formed in the discharge space. Since the materials are formed at the same time by the same process, the adhesion strength of the electrode pad portion 3a can be easily improved without increasing the number of manufacturing processes. In addition, since the electrode pad portions 3a and 7a are provided at the ends of the first substrate 2 in the longitudinal direction, and the electrode spacing walls 6c are provided between them, the device can be downsized, but the withstand voltage is high. A discharge light emitting device having characteristics can be obtained.
[0029]
Embodiment 2 FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 3 is a partial plan view showing details of the configuration of the first electrode 3 and the electrode pad 3a formed on the first substrate 2 before forming the discharge light emitting device according to the second embodiment, and FIG. FIG. 4 is a partial plan view showing a configuration of the discharge light emitting device after a second substrate 6 is disposed on the first substrate 2 shown in FIG. The discharge light-emitting device according to the second embodiment has the same configuration as the discharge light-emitting device 1 according to the first embodiment (however, the harness wire 10, the solder 12 and the like are not shown), but the width of the electrode pad 3a and its width. It differs from the discharge light emitting device 1 according to the first embodiment in that the tip is formed in a semicircular shape having a half width. By reducing the area of the electrode pad 3a and increasing the creepage distance with the electrode pad 7a, the withstand voltage characteristics between the electrodes can be further improved as compared with the case of the first embodiment.
[0030]
Next, withstand voltage characteristics of the discharge light emitting device 1 according to the second embodiment will be described with reference to FIG. FIG. 5 is a withstand voltage characteristic diagram showing a withstand voltage characteristic between electrodes of the discharge light emitting device shown in FIG. In FIG. 5, the horizontal axis represents the withstand voltage characteristic measurement voltage, and the vertical axis represents the occurrence rate (%) at each voltage (every 1 KV). The occurrence rates of the invention product (when the electrode pad 3a portion is reduced) and the conventional product are shown. Each is shown. As shown in FIG. 5, the discharge light emitting device according to the second embodiment (the invention in FIG. 5) has a higher withstand voltage characteristic than the conventional product (the conventional product in FIG. 5).
[0031]
Embodiment 3 FIG.
Next, a contact image sensor according to a third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a configuration sectional view showing a contact image sensor using the discharge light emitting device according to the first or second embodiment as a light source for irradiating a document. 6, reference numeral 1 denotes a discharge light emitting device used as a light source of the contact image sensor 100, for example, the discharge light emitting devices according to the first and second embodiments as shown in FIG. 1 or FIG. , 102 is formed on the housing 101, a mounting portion on which the discharge light emitting device 1 is mounted, 103 is a glass plate supported by the housing 101, 104 is a character, a chart, etc. An original, 105 is a rod lens array, 106 is a circuit board on which an array of light receiving elements 107 for receiving reflected light from the original 104 focused by the rod lens array is mounted, and 108 is a circuit board 106 fixed to the housing 101. It is a fixing screw. As shown in FIG. 6, the mounting portion 102 horizontally supports the first substrate 2 of the discharge light emitting device 1, whereby the glass plate 103 and the second substrate 6 of the discharge light emitting device 1 face each other. Are arranged as follows. Since the circuit board 106 is fixed to the housing 101 with the screws 108, the circuit board 106 can be easily replaced in the case of failure or the like.
[0032]
Further, since the inclined portion 6b of the discharge light emitting device 1 is disposed near the contact point between the document 104 conveyed by the platen roller (not shown) and the glass plate 103, the discharge light generated in the discharge space 9 is substantially. The light is emitted from the inclined portion 6b having a 45 ° inclination angle, and is irradiated to the contact point between the document 104 and the glass plate 103, that is, the irradiation point of the document 104, along a path indicated by an arrow in FIG. The light reflected by the document 104 is received by a light receiving element 107 mounted on a circuit board 106 via a rod lens array 105, and is subjected to photoelectric conversion processing on the circuit board 106.
[0033]
As described above, according to the contact image sensor according to the third embodiment, the necessary distance from the light emitting surface of the discharge light emitting device 1, that is, the inclined surface 6a to the irradiation surface of the document 104 can be reduced, and brighter illumination can be obtained. realizable. Generally, the brightness of the original surface (original surface illuminance) is proportional to the brightness of the light source and inversely proportional to the square of the distance between the light source and the original surface. By reducing the distance from the irradiation surface, the illuminance on the document surface can be improved. In addition, since unnecessary space between the light source and the document surface is reduced, disturbance due to reflection and scattering from other than the document surface can be suppressed, and high-precision document reading can be realized.
[0034]
Although the contact image sensor according to the third embodiment incorporates the discharge light emitting device 1 on only one side of the rod lens array 105, the mounting portions 102 are formed on both sides of the rod lens array 105 and are incorporated on both sides. May be configured. As described above, the brightness of the original surface (original surface illuminance) is proportional to the luminance of the light source. Therefore, brighter illumination can be realized by incorporating the discharge light emitting device 1 on both sides of the rod lens array 105.
[0035]
【The invention's effect】
As described above, according to the discharge light emitting device of the present invention, the adhesion strength of the electrode pad portion is improved, and the peeling of the electrode pad when the harness wire is connected to the electrode pad portion by soldering can be easily prevented. it can. Further, according to the discharge light emitting device according to the present invention, it is possible to reduce the size of the device, while improving the withstand voltage characteristics between the electrodes. Further, according to the contact image sensor according to the present invention, since the discharge light emitting device is used, highly reliable original reading can be realized.
[Brief description of the drawings]
FIG. 1 is a configuration sectional view and a partial plan view showing a discharge light emitting device according to a first embodiment.
2 is an adhesion strength measurement diagram showing measured values of adhesion strength of an electrode pad portion 3a of the discharge light emitting device shown in FIG.
FIG. 3 is a partial plan view showing an electrode configuration on a first substrate of the discharge light emitting device according to the second embodiment.
FIG. 4 is a partial plan view showing a discharge light emitting device according to a second embodiment.
FIG. 5 is a withstand voltage characteristic diagram showing measured values of withstand voltage characteristics of the discharge light emitting device shown in FIG.
FIG. 6 is a sectional view showing a configuration of a contact image sensor according to a third embodiment.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 discharge light emitting device, 2 first substrate, 3 first electrode, 3a electrode pad of first electrode 4 dielectric layer, 4a electrode pad of dielectric layer 4 3a tip coating dielectric layer, 5 phosphor layer, Reference Signs List 6 second substrate, 6a facing portion, 6b inclined portion, 6c electrode spacing wall, 7 second electrode, 7a electrode pad of second electrode 8 sealing portion, 9 discharge space, 10 harness wire, 11 core wire, 12 Solder, 100 contact image sensor, 101 frame, 102 mounting section, 103 glass plate, 104 document, 105 rod lens array, 106 circuit board, 107 sensor (light receiving element).

Claims (8)

A first substrate, a second substrate opposed to the first substrate, a sealing portion forming a discharge space between the first substrate and the second substrate, A first electrode provided in the discharge space on the first substrate, a dielectric layer provided in the discharge space on the first electrode, and a first electrode provided in the discharge space on the dielectric layer. A first phosphor layer, a second phosphor layer provided in the discharge space on the second substrate, and a second phosphor layer provided on the second substrate on a side opposite to the second phosphor layer. A second electrode, an inclined portion formed on the second substrate, for outputting light generated in the discharge space to the outside, and the first and second electrodes provided at an end in a longitudinal direction of the first substrate. First and second electrode pads connected to the first and second electrodes, respectively, on the first substrate and the electrode pads. Vignetting, discharge light emitting device is characterized in that a coating layer covering the periphery of the electrode pad portions. The discharge light emitting device according to claim 1, wherein the covering layer is a dielectric layer formed by the same process as a dielectric layer formed on the first substrate. The discharge light emitting device according to claim 1, wherein the dielectric layer is formed of glass containing BiO ₂ , ZnO, or B ₂ O ₃ as a main component. The discharge light emitting device according to claim 1, wherein the dielectric layer is formed of a heat-resistant insulating tape made of a polyimide resin. The discharge light emitting device according to claim 1, wherein a partition wall is provided between the first and second electrode pads. The discharge light emission according to any one of claims 1 to 4, wherein the first electrode pad portion has a tip portion formed in a semicircular shape having a half width of the line width. apparatus. The discharge light emitting device according to any one of claims 1 to 4, wherein the first electrode is made of Ag, Cu or Al. A contact image sensor comprising the discharge light emitting device according to any one of claims 1 to 6.

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