JP2010177306A - Led board device and led printhead - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LED board device for an LED printhead without degrading flatness (distorting, warping, bending) of a board due to repetition of heating/cooling in a manufacturing process. <P>SOLUTION: In this LED board device 5 including a long bare board 9 having a flat pattern formed on the front surface and having wiring patterns (161-167) of the same width formed on the back surface 11, and LED array chips fixed on the flat pattern in a linear or zigzag form, the wiring patterns (161-167) are divided into three or more groups, and arranged at equal intervals in the short-side direction of the bare board 9 in each group; extension patterns 21 are formed along the long-side direction of the bare board 9 in parts without having wiring pattern of an area 18 on the back surface corresponding to the flat patterns formed on the front surface; the width of the extension patterns 21 is identical to that of the wiring patterns (161-167); and the extension patterns 21 are formed at the same intervals as those of the wiring patterns in the short-side direction of the bare board 9. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an LED substrate device and an LED print head used in an image forming apparatus such as a laser printer or a digital copying machine.

  Conventionally, in order to form an electrostatic latent image of an image on an electrostatic latent image carrier such as a photosensitive drum of an image forming apparatus, an LED print head having an LED array chip and a lens array as main components has been used. ing.

  This LED print head has a long LED board device on which an LED array chip having a plurality of light emitting diodes (LEDs) is mounted (fixed), a long housing to which the LED board device is fixed, and the LED array chip. And a long lens array fixed to the housing (see, for example, Patent Documents 1 to 4).

In order to form an electrostatic latent image on the surface of the photosensitive drum with high accuracy, the LED print head needs to minimize variations in image forming points.
Here, the imaging point refers to a point (focal point) where light emitted from a plurality of LEDs (light emitting points) of the LED array chip converges through the lens array.

  A generally adopted means for reducing the variation in the image formation point is to make the flatness and straightness of the housing for fixing the LED substrate device highly accurate, and to maintain this high accuracy over a long period of time. . For this reason, the LED print head described in Patent Document 1 and Patent Document 2 is integrally molded with a housing and a rigid body. Moreover, the LED print head described in patent documents 3 and 4 has made the height of the optical axis direction of a housing high.

JP 2006-289843 A JP 2005-193638 A JP 2000-141744 A Japanese Patent Laid-Open No. 11-266037

  However, the above-described prior art is based on the premise that the flatness of the LED substrate device is poor, and does not improve the poor flatness of the LED substrate device itself.

This point will be further described in detail.
In general, a bare board used in an LED board device employs a printed board using a general-purpose glass epoxy base material (for example, FR-4) because of cost restrictions, productivity, and the like. Here, a glass epoxy base material means the thing of the structure which affixed copper foil to the glass cloth base material epoxy resin.

  The LED board device is manufactured by mounting an LED array chip or the like on such a bare board. At that time, heating and cooling are repeated. For example, 110 ° C. for 90 minutes in the curing process for mounting the LED array chip and curing the silver paste, and 250 ° C. for 5 seconds in the mounting process for electronic components such as drivers.

  Thus, in the manufacturing process of the LED substrate device, the flatness of the LED substrate device is deteriorated (distorted, warped, bent) by repeating heating and cooling. This is due to the difference in thermal expansion and contraction characteristics between the glass epoxy base material constituting the bare board and the copper foil attached to the glass epoxy base material.

  If the flatness of the LED substrate device is poor, it causes a deviation of the optical axis of the LED array chip, which becomes a serious problem in the print quality of the LED print head. In addition, the yield in the wire connection (wire bonding) process after the LED array chip is mounted is significantly deteriorated.

  The present invention has been made in order to solve the above-described problem, and is based on heating and cooling of the LED substrate device by a simple configuration in which an extended pattern obtained by extending the wiring pattern is provided in an area where the wiring pattern is not formed. The object is to eliminate the adverse effect on the flatness, and to reduce the cost and improve the yield of the LED board device, and hence the LED print head.

(First invention)
The LED board device according to the first aspect of the present invention is a long bare board in which a solid pattern is formed along the longitudinal direction on the front surface, and a plurality of wiring patterns having the same width dimension are formed along the longitudinal direction on the back surface. The present invention relates to an LED substrate device comprising a plurality of LED array chips fixed in a linear or staggered pattern on the solid pattern.

  Here, the solid pattern does not indicate a portion such as a copper foil having a large area used for a power supply pattern, a ground pattern, or the like in a general printed wiring board, but LED array chips are mounted in a linear or staggered pattern. This refers to a portion of copper foil or the like having a large linear area.

  The plurality of wiring patterns formed on the surface of the bare board are divided into a plurality of groups of three or more, and are arranged in this group mainly at equal intervals in the short direction of the bare board. An extension pattern in which the wiring pattern is extended is formed mainly along the longitudinal direction of the bare board at least in a portion where the wiring pattern is not formed in the area of the back surface corresponding to the solid pattern formed on the surface of the bare board. It is a thing. Further, the width dimension of the extension pattern is the same as the width dimension of the wiring pattern, and the extension pattern is formed at the same interval as the interval of the wiring pattern in the short direction of the bare board.

Here, the wiring pattern is an electronic component such as an LED array chip or IC (integrated circuit) mounted (fixed) on the bare board, and an electronic component mounted (fixed) on the bare boat and / or another bare board. Is a pattern for electrically connecting. That is, when it comes to the LED substrate device, it is a pattern directly related to the on (light emission) / off (non-light emission) operation of the LED array chip.
The extension pattern is an extension of the wiring pattern.
The wiring pattern and the solid pattern are preferably made of the same material such as a copper foil.

  The solid pattern formed on the surface of the LED substrate device is the most important part in the LED substrate device because the LED array chip is mounted, and the flatness of the solid pattern must be maintained with high accuracy.

  With the configuration described above, at least the density of the wiring pattern (wiring pattern layout) in the area of the back surface corresponding to the solid pattern can be made substantially uniform. Therefore, the particularly important part on which the LED array chip of the LED board device is mounted is the LED Deterioration of flatness due to heating and cooling in the manufacturing process of the substrate device can be suppressed (high flatness can be maintained). Moreover, the high flatness of the whole LED board apparatus is maintainable by providing an extended pattern in the substantially whole area (substantially whole surface) of the back surface of an LED board apparatus.

(Second invention)
The LED board device according to a second invention is the LED board device according to the first invention, wherein the width dimension of the wiring pattern and the interval between the wiring patterns are the same.

  With such a configuration, the density (layout) of the wiring pattern and the extension pattern can be made more uniform than in the first invention, so that the effect of the first invention can be further improved. In other words, since the configuration of the wiring pattern and the extended pattern in the area of the back surface corresponding to at least the solid pattern on the front surface repeats a certain pattern, the flatness of the LED substrate device deteriorates due to heating and cooling in the manufacturing process of the LED substrate device. Can be further suppressed.

(Third invention)
An LED print head according to a third aspect of the present invention is a lens array in which a plurality of rod lenses are arranged and arranged, a housing in which the lens array is fixed, and a housing in which one lens surface of the lens array faces the LED array chip. And the LED substrate device of the first invention or the second invention fixed to the board.

  With this configuration, since the flatness of the LED substrate device is high, it is possible to provide an LED print head with extremely small variations in image forming points.

  According to the present invention, it is possible to provide an LED substrate device that can maintain high flatness even when heated and cooled in the manufacturing process. In addition, since the flatness of the LED substrate device is high, it is possible to provide an LED print head with extremely small variations in image forming points.

Plan view of LED print head (Example 1) LED print head perspective view (Example 1) Sectional view of LED print head (Example 1) Plan view of LED substrate device (Example 1) A perspective view of the surface of the LED substrate device (Example 1) A perspective view of the back surface of the LED substrate device (Example 1) Plan view of the back surface of the LED substrate device (Example 1) Plan view of the back surface of the LED substrate device (Example 2)

Hereinafter, the present invention will be described in detail using examples.
In the drawings used in each embodiment, the wiring pattern and the extension pattern are shown thick, but this is for easy understanding of the description, and actually has a width of several hundred to several tens of microns.

A first embodiment according to the present invention will be described with reference to FIGS.
(LED print head)
As shown in FIGS. 1 to 3, the LED print head 1 according to the present invention includes a housing 2 in which a lens array 3 in which a plurality of rod lenses 6 are arranged and fixed is fixed with an adhesive or the like, and one lens of the lens array 3. The LED board device 5 described later is fixed to the housing 2 with an adhesive or the like so that the LED array chip 4 faces the surface.

  As shown in FIG. 3, the LED print head 1 emits light from the light emitting point when the light emitting point (LED) of the LED array chip 4 mounted (fixed) on the surface 10 of the LED substrate device 5 is caused to emit light. The distance to the image forming point (focal position) where the reflected light is converged (condensed) by the lens array 3 is set to the conjugate length TC. The conjugate length TC includes a distance L from the LED light emitting surface to the lower surface (one lens surface) of the lens array 3, a distance L from the upper surface (the other lens surface) of the lens array 4 to the imaging point, and the lens array. 4 and the height T, and the relationship TC = T + 2L is established.

  Further, as will be described later, since the flatness of the LED board device is high, and the high flatness of the LED board device can be maintained even by repeated temperature changes due to the on / off operation of the LED array chip, the LED print head according to the present invention. As shown in FIGS. 1 and 2, a rigid plate or the like is not required on the back surface of the LED substrate device. That is, it is possible to provide an inexpensive and high-accuracy LED print head with few LED print head components and little variation in image formation point.

  Although FIGS. 1 to 3 show the LED print heads fixed in a staggered pattern, they may be fixed in a straight line, and even in this case, the effects described above can be obtained. .

(LED board device)
An LED substrate device 5 according to the present invention is shown in FIGS. FIG. 5 is an enlarged perspective view of one end W surrounded by a two-dot chain line in FIG. FIG. 7 is a plan view of the back surface of the portion W, and FIG. 6 is a perspective view (without an extension pattern) when artwork is designed on the back surface of the portion W by a general method. FIG. 6 is a diagram for explaining FIG. Moreover, the following description is only about the one end part W in FIG. Description of parts other than the one end part W is omitted because it is a repetition of substantially the same configuration in which the LED array chip 4 is continuously fixed in a straight line or zigzag form from the one end part W to the other end.

  As shown in FIG. 5, the LED substrate device 5 includes a solid pattern 8 made of copper having a predetermined width on the front surface 10 along the longitudinal direction (Y direction), and a plurality of the same width dimension A on the back surface 11. The wiring pattern 16 includes a long bare board 9 formed mainly along the longitudinal direction (Y direction). A plurality of LED array chips 4 are fixed on the surface of the solid pattern 8 in a staggered manner.

  4 and 5 show the LED array chips 4 fixed in a zigzag pattern, the LED array chips 4 may be fixed in a straight line. Further, the width (X direction) of the solid pattern 8 may be any width that allows the LED array chip to be fixed in a straight line shape or a staggered shape.

  A light emitting point (LED) (not shown) is formed in a straight line on the surface of the LED array chip 4, and a plurality of pads 13 are also formed. The plurality of pads 13 and the plurality of pads 14 formed on the surface of the bare board are connected by wires 12. In FIG. 5, only one pad 13 and 14 is shown for the sake of simplicity.

As shown in FIG. 6, when the artwork is designed based on a general method, a plurality of wiring patterns 16 (161 to 167) made of copper are mainly formed on the back surface 11 of the bare board 9 in the longitudinal direction of the bare board 9. Formed along.
Here, “the wiring pattern 16 is mainly formed along the longitudinal direction” means that most of the wiring pattern 16 (most of the entire length of the wiring pattern 16) is formed along the longitudinal direction (Y direction). It means that More specifically, for example, a wiring pattern along the longitudinal direction (Y direction) excluding a part of the wiring pattern 16 in the short direction (X direction) such as connecting to the IC (integrated circuit) 19 in FIG. 16 is the majority.

  These wiring patterns 16 are divided into two sets (wiring pattern bundles) of a first set of wiring patterns 161, 162, 163 and 164 and a second set of wiring patterns 165, 166 and 167. The wiring patterns 16 are arranged at intervals B equal to the short direction (X direction) of the bare board 9 in each set.

  That is, the width dimension of the first set of wiring patterns 161 to 164 is A, and the distance between the wiring patterns 161 and 162, the distance between the wiring patterns 162 and 163, and the distance between the wiring patterns 163 and 164 are B. The width dimension of the second set of wiring patterns 165, 166, and 167 is A, the distance between the wiring patterns 165 and 166 is B, and the distance between the wiring patterns 166 and 167 is also B.

In the present invention, as shown in FIG. 6, on the back surface 11 of the bare board 9, at least wiring in an area 18 (a portion surrounded by a two-dot chain line) corresponding to the solid pattern 8 formed on the front surface 10 of the bare board 9 As shown in FIG. 7, a plurality of extended patterns 21 are mainly formed along the longitudinal direction (Y direction) of the bare board 9 in the area (part) 20 where the pattern 16 is not formed.
Here, “the area 18 of the back surface 11 corresponding to the solid pattern 8 formed on the front surface 10” refers to a portion occupied in the back surface 11 when the solid pattern 8 formed on the front surface 10 is seen through the back surface 11. Say.

As can be seen by comparing FIG. 6 and FIG. 7, an extension pattern 21 in which a part of the wiring pattern 163 is extended is formed in the area 20 in FIG. 6, and the extension pattern 21 in which a part of the wiring pattern 165 is extended. Is formed.
These extended patterns 21 are mainly formed along the longitudinal direction (Y direction) of the bare board 9.

As shown in FIG. 7, the width dimension C of each extension pattern 21 formed on the back surface 11 is the same as the width dimension A of the wiring pattern 16. Further, the distance D between the extended patterns 21 is the same as the distance B between the wiring patterns 16 in the short direction (X direction) of the bare board 9.
In Example 1, the width dimension C = the width dimension A = 150 microns, and the interval D = the interval B = 100 microns.

  With this configuration, the area 18 of the back surface 11 corresponding to the solid pattern 8 formed on the front surface 10 of the bare board 9 can substantially equalize the density of the wiring pattern 16 and the extension pattern 21, that is, with / without a predetermined pattern. Since the repetition is constant, even when heating and cooling are repeated in the manufacturing process of the LED substrate device 5, the flatness of the solid pattern 8 does not deteriorate due to warpage of the solid pattern 8 in the LED substrate device 5 (initially) High flatness).

  Moreover, even if the heating and cooling of the LED substrate device 5 are repeated by the on / off operation of the plurality of LED array chips 4 fixed to the solid pattern 8, the initial high flatness of the solid pattern 8 can be maintained.

  For this reason, since the optical axis of the LED array chip 4 fixed to the solid pattern 8 formed on the surface 10 is not shifted, when the LED substrate device 5 is used for the LED print head 1 described above, the LED array chip The imaging lines formed by the plurality of imaging points formed by the light emitted from the plurality of light emitting points 4 passing through the lens array 3 can maintain linearity with high accuracy. That is, the image forming apparatus using the LED print head 1 can form a high-precision electrostatic latent image on the surface of the photosensitive drum, and can form a high-precision image on recording paper or the like.

A second embodiment according to the present invention will be described with reference to FIG.
Note that only differences from the first embodiment will be described for easy understanding.

The second embodiment is different from the first embodiment in that the extension pattern 21 is provided also in the portion other than the area 18 in FIG. 7 of the first embodiment.
That is, as shown in FIG. 8, the extension patterns 21 are also provided for the wiring patterns 161 and 167 in FIG.

  In the case of such a configuration, the density of the pattern composed of the wiring pattern 16 and the extension pattern 21 can be made substantially uniform over the entire back surface of the bare board 9, so that the effect of the first embodiment can be further improved.

  That is, high flatness of the LED substrate device 5 as a whole can be maintained against repeated heating and cooling also in the portion other than the portion 18 corresponding to the back surface 11 where the solid pattern 8 is formed on the front surface 10.

The difference between the third embodiment and the first embodiment is that the width dimension of the wiring pattern and the interval between the wiring patterns are the same.
This will be described in further detail with reference to FIG. That is, the width dimension C of each of the plurality of extension patterns 21 formed on the back surface 11 is the same as the width dimension A of the wiring pattern 16, and the distance D between the extension patterns 21 is the short direction of the bare board 9. This is the same as the interval B of the wiring pattern 16 in the (X direction). Furthermore, in the third embodiment, since the width C of the wiring pattern and the interval B of the wiring pattern are made the same, width A = width C = interval B = interval D = 100 microns.

  With this configuration, the density of the wiring pattern 16 and the extension pattern 21 can be made more uniform than in the case of the first embodiment, so that the effect of the first embodiment can be further improved. That is, since the configuration of the wiring pattern 16 and the extension pattern 21 in the area 18 on the back surface corresponding to the solid pattern 8 on the front surface 10 is a constant pattern, the LED substrate is heated and cooled in the manufacturing process of the LED substrate device 5. The deterioration of the flatness of the device 5 can be further suppressed.

  The above-described embodiments have been illustrated for the purpose of explanation, and the present invention is not limited thereto. Those skilled in the art will recognize from the claims, the detailed description of the invention, and the drawings. Modifications and additions can be made without departing from the technical idea of the present invention.

  In the above-described embodiment, the wiring pattern 16 having a width A of 100 microns is shown, but it may be 75 microns or 50 microns. Furthermore, in Example 6, the width dimension A = width dimension C = interval B = interval D may be 75 microns or 50 microns.

  Further, in the above-described embodiment, the extension pattern 21 is provided on the inner wiring patterns 163, 164 and 165 and the outer wiring patterns 161 and 167 in the set of the wiring patterns 16. The extension pattern 21 may also be provided for the wiring patterns 162 and 166 formed inside each set.

  The present invention is applied to an LED print head used in a copying machine, a printer, and the like, and an LED substrate device used in the LED print head.

DESCRIPTION OF SYMBOLS 1 LED print head 2 Housing 3 Lens array 4 LED array chip 5 LED board apparatus 6 Rod lens 8 Solid pattern 9 Bare board 10 Front surface 11 Back surface 16 Wiring pattern 17 Test pad 21 Extension pattern

Claims (3)

A long bare board in which a solid pattern is formed along the longitudinal direction on the front surface, and a plurality of wiring patterns having the same width dimension are mainly formed along the longitudinal direction on the back surface;
A plurality of LED array chips fixed linearly or in a staggered pattern on the solid pattern,
The plurality of wiring patterns are divided into a plurality of sets of three or more, and are arranged at equal intervals mainly in the short direction of the bare board in the set,
At least at the portion where the wiring pattern is not formed in the area of the back surface corresponding to the solid pattern formed on the front surface, an extended pattern in which the wiring pattern is extended mainly along the longitudinal direction of the bare board Formed,
The width dimension of the extension pattern is the same as the width dimension of the wiring pattern,
The extended pattern is formed at the same interval as the interval of the wiring patterns in the short direction of the bare board.   The LED board device according to claim 1, wherein a width dimension of the wiring pattern and an interval between the wiring patterns are the same. A lens array in which a plurality of rod lenses are arranged and arranged;
A housing to which the lens array is fixed;
3. An LED print head comprising: the LED substrate device according to claim 1 or 2, which is fixed to the housing so that one lens surface of the lens array faces the LED array chip.

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