JP3702123B2 - Optical printer head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical printer head used as exposure means for an electrophotographic printer or the like.
[0002]
[Prior art]
Conventionally, an optical printer head such as an LED array head has been used as an exposure means for an electrophotographic printer or the like.
[0003]
As such a conventional optical printer head, light emission such as a light emitting diode element array chip (hereinafter abbreviated as an LED array chip) is provided on the upper surface of a head substrate on which a circuit wiring of a predetermined pattern is deposited and formed on a transparent substrate. It is known that a predetermined number of element array chips are mounted. The light emitting elements on the lower surface of the light emitting element array chip are selectively made to emit light individually based on image data from the outside, and the emitted light is transmitted to a transparent substrate or It functions as an optical printer head by irradiating and forming an image on an external photoconductor through an optical system such as a lens disposed below the substrate and forming a predetermined latent image on the photoconductor.
[0004]
The light emitting element array chip is mounted at a predetermined position on the upper surface of the head substrate by a conventionally known face-down bonding or the like, whereby the terminal electrode of the light emitting element array chip and the circuit wiring of the head substrate corresponding to the electrode are electrically connected. Will be connected.
[0005]
Further, as a connection member used for electrical connection between the circuit wiring and the terminal electrode, attention is paid to an anisotropic conductive adhesive that can be easily connected. This anisotropic conductive adhesive is formed by adding metal fine particles such as Ni and Ag to an organic component composed of a precursor such as an epoxy resin, and the anisotropic conductive adhesive is applied to a predetermined region on the upper surface of the transparent substrate, specifically Specifically, it is applied to a region where the circuit wiring and the terminal electrode face each other, and the lower surface of the light emitting element array chip is pressed against the coated surface, so that the metal fine particles in the anisotropic conductive adhesive are placed between the circuit wiring and the terminal electrode. The circuit wiring and the terminal electrode are electrically connected through the metal fine particles in the anisotropic conductive adhesive.
[0006]
[Problems to be solved by the invention]
However, when assembling this conventional optical printer head, the anisotropic conductive adhesive used to connect the circuit wiring and the terminal electrode flows due to the application of external force, and a part thereof extends to the region directly under the light emitting element. There is. In that case, a part of the light emitted from the light emitting element hits the metal fine particles in the anisotropic conductive adhesive and diffuses in all directions, and a part of the diffused light is irradiated as unnecessary light to the photoconductor, or This has the disadvantage that the intensity of light applied to the photoreceptor is lowered and the latent image becomes unclear.
[0007]
[Means for Solving the Problems]
The present invention has been devised in view of the above disadvantages, and the optical printer head of the present invention has a plurality of circuit wirings arranged on a transparent substrate having a pair of grooves formed on a top surface thereof in parallel. A head substrate formed by attaching one end and / or the other end of the circuit wiring from the outside so as to extend onto the groove, a plurality of light emitting elements arranged linearly on the lower surface, and each light emitting element electrically A light-emitting element array chip having a plurality of terminal electrodes connected thereto, the light-emitting element array chip on the head substrate, the array of the light-emitting elements is located between the pair of grooves, and the terminal electrode Are connected to each other on the outside of the pair of grooves via an anisotropic conductive adhesive in which a black pigment is added and mixed, and the anisotropy is provided between the circuit board and the light emitting element array chip. One of conductive adhesive The so housed inside the pair of grooves is characterized in that was attached.
[0008]
In the optical printer head of the present invention, the transparent substrate is formed by depositing a glass layer having a melting point lower than that of the glass substrate on the upper surface of the glass substrate, and the pair of grooves are formed in the glass layer. It is characterized by being.
[0009]
Furthermore, the optical printer head of the present invention is characterized in that, in each of the above-described configurations, the inner wall surface of the groove or the recess is inclined so that the width of the groove is larger on the opening side than the bottom.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
(First form)
FIG. 1 is a cross-sectional view of an optical printer head according to the first embodiment of the present invention, wherein 1 is a head substrate, 2 is a transparent substrate, 3 and 3 are a pair of grooves, 4 is a circuit wiring, and 5 is a light emitting element array chip. LED array chip, 6 is a light emitting diode element as a light emitting element, 7 is a terminal electrode, and 8 is an anisotropic conductive adhesive.
[0011]
The head substrate 1 has a structure in which a plurality of circuit wirings 4 are deposited in a predetermined pattern on a transparent substrate 2 having a pair of grooves 3 and 3 deposited substantially parallel on the upper surface.
[0012]
The transparent substrate 2 is made of a light-transmitting electrically insulating material such as borosilicate glass, soda glass, quartz, sapphire, or crystallized glass, and supports the circuit wiring 4 and the LED array chip 5 on its upper surface. It functions as a support base material for. Here, the substrate 2 is formed of a transparent material so that the light of the light emitting diode element 6 of the LED array chip 5 is transmitted in the thickness direction of the substrate 2 and guided to the lower surface side of the substrate 2, that is, the photoreceptor side. Because.
[0013]
The pair of grooves 3 and 3 formed on the upper surface of the transparent substrate 2 are formed so as to be substantially parallel (within ± 3 °) along the longitudinal direction of the transparent substrate 2 and each have a V-shaped cross section. ing.
[0014]
The pair of grooves 3 and 3 are arranged so that an array of light emitting diode elements 6 to be described later is positioned between them, and the depth of each groove 3 is, for example, 0.02 mm to 0.30 mm, and each groove The V-shaped angle θ between the two inner wall surfaces 3 is set to 60 ° to 150 °, for example, and the inner wall surfaces of the grooves 3 and 3 are set to be inclined 30 ° to 75 ° with respect to the thickness direction of the transparent substrate 2. The
[0015]
The pair of grooves 3 and 3 serve to block the flow when the anisotropic conductive adhesive 8 is about to flow toward the light emitting diode element 6 when the optical printer head is assembled. It is effective that a part of the anisotropic conductive adhesive 8 is satisfactorily accommodated in the grooves 3 and 3 so that a part of the anisotropic conductive adhesive 8 extends directly under the light emitting diode element 6. Can be prevented. Therefore, the light from the light emitting diode element 6 of the LED array chip 5 is unlikely to be scattered by hitting the metal fine particles in the anisotropic conductive adhesive 8, and the intensity of the light irradiated to the photoconductor is kept high and clear. In addition, a good latent image can be formed.
[0016]
In this case, since the cross-sectional shape of the pair of grooves 3, 3 is V-shaped as described above, the width of the grooves 3, 3 is larger on the opening side than the bottom, and therefore, anisotropic The excess of the conductive conductive adhesive 8 is easily introduced into the grooves 3 and 3. Therefore, the above-mentioned damming action of the anisotropic conductive adhesive 8 is further ensured by the grooves 3, 3 having a V-shaped cross section.
[0017]
Further, in this case, if a light-shielding film made of a colored resin having a light transmittance of 50% or less is attached to the inner surfaces of the grooves 3 and 3, the light from the light-emitting diode element 6 spreads beyond the grooves 3 and 3. It is effectively prevented that the beam is struck, and the diameters of the respective beams (lights) irradiated to the photosensitive member are made almost equal. Therefore, it is preferable to deposit a light-shielding film having a light transmittance of 50% or less on the inner surfaces of the grooves 3 and 3.
[0018]
The pair of grooves 3 and 3 are formed to have a predetermined width and a predetermined depth by employing a conventionally known dicing method, a laser processing method, or the like and physically processing the upper surface of the transparent substrate 2.
[0019]
Further, the plurality of circuit wires 4 to be deposited on the upper surface of the transparent substrate 2 are deposited such that one end and / or the other end thereof extends to the grooves 3 and 3.
[0020]
The plurality of circuit wirings 4 are made of a conductive material such as copper (Cu), silver (Ag), gold (Au), aluminum (Al), etc., and each of them is a corresponding terminal of the LED array chip 5 in the vicinity of the groove 3. By electrically connecting to the electrode 7, it functions as a power supply wiring for supplying power from an external power source to each light emitting diode element 6 of the LED array chip 5.
[0021]
The circuit wiring 4 is printed and applied in a predetermined pattern on the upper surface of the transparent substrate 2 on which the grooves 3 and 3 are applied by means of screen printing or the like known in the art by using a conductive paste containing the conductive material. Depositing and forming the conductive material on the upper surface of the transparent substrate 2 by baking at a high temperature or by processing the conductive material into a predetermined pattern using a well-known thin film technique, specifically, sputtering, photolithography, etching or the like. Is done. In particular, when the circuit wiring 4 is patterned by screen printing, the edge (one end and / or the other end) of the printed pattern is located on the grooves 3 and 3, so that the screen plate and the transparent substrate 2 are in this portion. The advantage of the manufacturing method that the distance from the upper surface is widened, so that the conductive paste applied to the grooves 3 and 3 is better than other parts and the pattern shape of the circuit wiring 4 can be easily controlled. There is. At this time, if the V-shaped angle θ of the groove 3 is set within the range of 60 ° to 90 °, the sagging of the printing paste is reduced, and the above-described pattern shape control can be performed more easily.
[0022]
On the head substrate 1, a plurality of LED array chips 5 are attached and mounted in a line by well-known face-down bonding.
[0023]
The LED array chip 5 includes a plurality of light emitting diode elements 6 arranged in a straight line on each lower surface, and a plurality of terminal electrodes 7 electrically connected to the light emitting diode elements 6. A conductive adhesive such as an anisotropic conductive adhesive 8 is interposed between each terminal electrode 7 and the circuit wiring 4 corresponding to the electrode 7, and both are electrically connected in the vicinity of the groove 3. It is mounted on the upper surface of the transparent substrate 2 by being connected.
[0024]
The light emitting diode elements 6 of the LED array chip 5 are individually selected based on image data from the outside when electric power from an external power source is supplied via the circuit wiring 4 of the head substrate 1 or the terminal electrodes 7. The photosensitive member is irradiated with the emitted light through an optical system such as a transparent substrate 2 or a lens (not shown) disposed below the substrate 2 to give a predetermined photosensitive member to the photosensitive member. A latent image is formed.
[0025]
As the light emitting diode element 6 of the LED array chip 5, for example, an AlGaAs light emitting diode element or the like is used, and the LED array chip 5 is manufactured by adopting a conventionally well-known semiconductor manufacturing technique.
[0026]
The anisotropic conductive adhesive 8 for electrically connecting the terminal electrode 7 of the LED array chip 5 and the circuit wiring 4 of the head substrate 1 is made of metal fine particles such as Au and Ni in an adhesive such as an epoxy resin. (Particle size: 3 to 10 μm) is added and mixed at a predetermined ratio, and the liquid material of the anisotropic conductive adhesive 8 is added along a predetermined region on the upper surface of the head substrate, specifically along the grooves 3 and 3. The epoxy resin is applied in the form of a belt, and the lower surface of the LED array chip 5 is pressed against the application surface, and the metal fine particles in the anisotropic conductive adhesive 8 are sandwiched between the terminal electrode 7 and the circuit wiring 4 By thermally curing the adhesive component such as the above, the LED array chip 5 is attached onto the head substrate 1 and the circuit wiring 4 and the terminal electrode 7 are electrically connected simultaneously.
[0027]
At this time, since the anisotropic conductive adhesive 8 is partially accommodated in the grooves 3 and 3 as described above, the anisotropic conductive adhesive 8 is used when mounting the LED array chip 5 or the like. Even if the agent 8 tends to flow greatly due to an external pressing force or the like, the flow is blocked by the pair of grooves 3 and 3, and a part of the anisotropic conductive adhesive 8 reaches the region immediately below the light emitting diode element 6. Can be effectively prevented. Therefore, the light from the light emitting diode element 6 of the LED array chip 5 is unlikely to be scattered by hitting the metal fine particles in the anisotropic conductive adhesive 8, and the intensity of the light irradiated to the photoconductor is kept high and clear. In addition, a good latent image can be formed.
[0028]
Further, a black pigment such as carbon or iron oxide powder is added to and mixed in the anisotropic conductive adhesive 8 at a ratio of 1 to 50% by weight, so that the light transmittance of the anisotropic conductive adhesive 8 is 5 to 30%. If it is set within this range, even if light leaks from the space between the LED array chip 5 and the head substrate 1, the leakage can be satisfactorily absorbed by the aforementioned black pigment. Therefore, black pigments such as carbon and iron oxide powder are added to and mixed in the anisotropic conductive adhesive 8 in a proportion of 1 to 50% by weight, so that the light transmittance of the anisotropic conductive adhesive 8 is 5 to 30%. It is preferable to set within the range.
[0029]
Thus, the above-described optical printer head supplies power from an external power source to the light emitting diode element 6 of the LED array chip 5 attached to the upper surface of the head substrate 1 via the circuit wiring 4 and the terminal electrode 7, etc. 6 is selectively emitted on the basis of image data, and the emitted light is irradiated and imaged on an external photoconductor via an optical system such as a lens (not shown) to form a predetermined latent image on the photoconductor. By forming it, it functions as an optical printer head.
[0030]
(Second form)
Next, a second embodiment of the optical printer head of the present invention will be described with reference to FIG. Note that the same components as those of the optical printer head of the first embodiment described above are denoted by the same reference numerals and description thereof is omitted, and only differences from the first embodiment will be described here.
[0031]
The optical printer head of the second embodiment is different from that of the first embodiment in that the transparent substrate 2 has a structure in which a glass layer 2b is attached to the upper surface of the glass substrate 2a, and a pair of grooves 3 are formed in the glass layer 2b. , 3.
[0032]
The glass layer 2b is formed of glass having a melting point lower than that of the glass substrate 2a. For example, a glass paste is applied in a predetermined thickness and a predetermined pattern by screen printing or the like known in the art, and then the temperature is 500 ° C. to 600 ° C. Formed by baking with. The screen plate used at this time is provided with openings corresponding to the grooves 3 and 3, and the glass paste is applied to the upper surface of the glass substrate 2a through the openings. The grooves 3, 3 formed by such a manufacturing method are trapezoidal in cross section, specifically, the inner wall surface is inclined outward with respect to the thickness direction of the glass layer 2b so that the width is larger on the opening side than the bottom portion. It becomes a shape.
[0033]
Further, on the upper surface of the glass layer 2b, circuit wiring 4 having one end and / or the other end extending to the grooves 3 and 3 is deposited and formed in a predetermined pattern. Electrically connected to the corresponding terminal electrode 7 of the LED array chip 5 through the anisotropic conductive adhesive 8 in the vicinity of the edges of the grooves 3 and 3.
[0034]
Also in the optical printer head of this second embodiment, since the light emitting diode element 6 on the lower surface of the LED array chip 5 is located between the pair of grooves 3, 3, the surplus of the anisotropic conductive adhesive 8 is the groove 3, 3. 3 will be housed inside. Therefore, even when the anisotropic conductive adhesive 8 tries to flow greatly due to external pressing force during the mounting operation of the LED array chip 5, etc., the flow is blocked by the pair of grooves 3 and 3, and the anisotropic conductive adhesive 8 It is possible to effectively prevent a part of the adhesive 8 from reaching the region immediately below the light emitting diode element 6. Therefore, the light from the light emitting diode element 6 of the LED array chip 5 hardly scatters by hitting the metal fine particles in the anisotropic conductive adhesive 8, and the intensity of the light irradiated to the photoconductor is kept high and clear. And a good latent image can be formed.
[0035]
In addition, this invention is not limited to the form mentioned above, A various change, improvement, etc. are possible in the range which does not deviate from the summary of this invention.
[0036]
For example, in the first embodiment described above, a pair of grooves 3 and 3 are formed on the upper surface of the transparent substrate 2 so that one end and / or the other end of the circuit wiring 4 extends to the grooves 3 and 3. Instead, a plurality of recesses are formed in two rows on the upper surface of the transparent substrate 2, and the circuit wiring 4 on the upper surface of the transparent substrate 2 extends to one end and / or the other end of the wiring 4 over the recess. It may be deposited as it exists. In this case, the concave portion is formed in a conical or hemispherical shape, and the LED array chip 5 is arranged on the head substrate 1 so that the array of the light emitting diode elements 6 is located between the two rows of concave portion arrays. It will be attached. At this time, if the inner wall surface of the concave portion is inclined so that the width of the concave portion is larger on the opening side than the bottom portion, excess of the anisotropic conductive adhesive 8 is easily introduced into the concave portion, The damming action of the anisotropic conductive adhesive 8 described above can be made more reliable. In addition, the width | variety of a recessed part here points out the maximum width which concerns on the direction orthogonal to the arrangement direction of a recessed part.
[0037]
In the first embodiment, the groove 3 on the upper surface of the transparent substrate 2 has a V-shaped cross section. Instead, it has a circular arc shape or a trapezoidal cross section with a radius of curvature of 0.02 to 0.30 mm. It doesn't matter.
[0038]
Further, in the second embodiment described above, the grooves 3 and 3 of the glass layer 2b are formed by screen printing using a screen plate of a predetermined pattern. Instead, the glass layer is once formed with a certain thickness, and then The grooves 3 and 3 may be formed by removing a part of the glass layer by dicing or the like.
[0039]
Furthermore, in the first and second embodiments described above, the LED printer head is configured by applying the LED array chip 5 as the light emitting element array, but other optical printer heads such as an EL head, a plasma dot head, a liquid crystal shutter, and the like. The present invention can also be applied to a head, a fluorescent head, PLZT, and the like.
[0040]
【The invention's effect】
According to the optical printer head of the present invention, even when the anisotropic conductive adhesive for connecting the terminal electrode to the circuit wiring outside the pair of grooves flows to the light emitting element side when the optical printer head is assembled, the flow Can be effectively prevented from partly reaching the region immediately below the light emitting element between the pair of grooves. Also, since black pigment is added to and mixed with the anisotropic conductive adhesive, even if light from the light emitting element leaks to the outside from between the light emitting element array chip and the head substrate, the leakage is anisotropic. It can be absorbed well with the black pigment added and mixed in the conductive adhesive. Accordingly, it is possible to irradiate the external photoconductor while maintaining the light emitted from the light emitting element at a high intensity, whereby a clear and good latent image can be formed.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an optical printer head according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view of an optical printer head according to a second embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Head substrate, 2 ... Transparent substrate, 2a ... Glass substrate, 2b ... Glass layer, 3, 3 ... Pair of grooves, 4 ... Circuit wiring, 5 ... LED Array chip (light emitting element array chip), 6 ... Light emitting diode element (light emitting element), 7 ... Terminal electrode, 8 ... Anisotropic conductive adhesive

Claims (3)

A plurality of circuit wires are deposited on a transparent substrate having a pair of grooves formed substantially parallel on the upper surface so that one end and / or the other end of the circuit wires extend from the outside of the pair of grooves to the groove. A head substrate,
A light emitting element array chip having a plurality of light emitting elements arranged linearly on the lower surface and a plurality of terminal electrodes electrically connected to the light emitting elements,
It said light emitting element array chip to the head substrate, an array of the light emitting element is positioned between the pair of grooves, and adding and mixing a black pigment and the terminal electrode in the circuit wiring, respectively outside of the pair of grooves preparative and a portion of the anisotropic conductive adhesive between said circuit board and said light emitting element array chip together to connect via the anisotropic conductive adhesive agent was allowed to accommodated inside the pair of grooves An optical printer head characterized by being worn. The transparent substrate is a low melting point glass layer than the glass substrate on the upper surface of the glass substrate becomes are adhered, the pair of grooves according to claim 1, characterized in that it is formed on the glass layer optical printer head of. The optical printer head according to claim 1, wherein an inner wall surface of the groove or the recess is inclined so that the width of the groove is larger on the opening side than the bottom.

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