JP3692247B2 - Optical printer head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical printer head such as an LED printer head incorporated as exposure means for an electrophotographic printer or the like.
[0002]
[Prior art]
A conventional optical printer head includes a light emitting element array chip in which a large number of light emitting elements are linearly arranged on one main surface of a circuit board to which circuit wiring of a predetermined pattern is attached, a switching transistor, a latch, A driver IC in which a shift register or the like is integrated is mounted, and the driver IC is housed in a housing in which an optical system such as a self-focusing lens array is attached. The light emitting elements of the element array chip are selectively made to emit light individually based on the printing data from the outside, and the emitted light is irradiated and imaged on the external photoconductor via the optical system, so that the photoconductor It functions as an optical printer head by forming a latent image.
[0003]
The driver IC is for controlling the light emission of the light emitting element, and the driver IC, the light emitting element array chip and the like are mounted on one main surface of the circuit board by a die mounter or the like. This mounting uses a well-known image processing technique. The light emitting element array chip and the driver IC are mounted while recognizing the position with reference to a marker provided on the surface of the circuit board, the light emitting element array chip, and the driver IC. I was trying to position it.
[0004]
[Problems to be solved by the invention]
By the way, with the recent increase in printing speed and the like, the transfer frequency of printing data has become extremely high, and radiation noise generated from driver ICs and signal wiring has become a big problem. Since this radiation noise may cause radio interference in other electronic devices arranged around the optical printer head, it is obliged to suppress this radiation noise to a predetermined intensity or less. The housing is made of a conductive material such as SUS, and the housing is connected to the ground potential to prevent radiation noise from leaking outside.
[0005]
However, this conventional optical printer head has the disadvantage that it is not suitable for mass production because the entire housing needs to be formed of the above-mentioned conductive material, resulting in a significant increase in cost of the product.
[0006]
In the conventional optical printer head described above, crosstalk noise or the like from adjacent wiring may enter the driver IC. In such a case, a malfunction of the driver IC is induced and a predetermined latent image is formed on the photoconductor. It had the disadvantage that it was impossible to do.
[0007]
Furthermore, in the conventional optical printer head, the light emitting element array chip and the driver IC are mounted on the circuit board by a die mounter or the like. In addition, an expensive image processing apparatus with high resolution is required, and as a result, the productivity of the optical printer head is significantly reduced.
[0008]
[Means for Solving the Problems]
The present invention has been devised in view of the above disadvantages. An optical printer head according to the present invention controls a light emitting element array chip in which a large number of light emitting elements are linearly arranged on one main surface and light emission of the light emitting elements. A head substrate on which a driver IC is mounted on one main surface of the transparent substrate by face-down bonding, a hole corresponding to the outer shape of the driver IC, and a side surface of the light emitting element array chip abuts on one end surface on the back side. A metal plate processed into a comb-like shape, the metal plate is disposed on one main surface of the transparent substrate, the driver IC is disposed in the hole, and the side surface of the light emitting element array chip is the one side It is characterized by being placed so as to be in contact with the end face.
[0009]
The optical printer head of the present invention is characterized in that the head substrate and the metal plate are housed in a housing and the other end surface of the metal plate facing the one end surface is brought into contact with the inner wall of the housing. To do.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
1 is a longitudinal sectional view of an optical printer head according to an embodiment of the present invention, FIG. 2 is a transverse sectional view of the optical printer head of FIG. 1, 1 is a head substrate, 3 is a light emitting element array chip, and 4 is a driver IC. 5 is a metal plate, 5a is a hole, 6, 7 is a housing, and 8 is a lens.
[0011]
The head substrate 1 includes a plurality of light emitting element array chips 3 on one main surface (lower surface) of a transparent substrate 2 on which a plurality of power supply lines and signal lines (not shown) are attached in a predetermined pattern. It has a structure in which a driver IC 4 is mounted.
[0012]
The transparent substrate 2 is made of an electrically insulating material having translucency such as borosilicate glass, soda glass, quartz, sapphire, crystallized glass, and the like. It functions as a support base material for supporting IC4 and the like. The reason why the substrate 2 is formed of a transparent material is that light from the light emitting elements of the light emitting element array chip 3 is transmitted in the thickness direction of the substrate 2 and guided to the external photoreceptor side.
[0013]
The power supply wiring attached to one main surface of the transparent substrate 2 serves to supply electric power from the outside to the light emitting element array chip 3 and the driver IC 4 to be described later, and the signal wiring is print data from the outside. Etc. are supplied to the driver IC 4.
[0014]
The plurality of light emitting element array chips 3 mounted on one main surface of the transparent substrate 2 includes a plurality of light emitting elements arranged in a straight line on each lower surface, for example, 64 to 128 light emitting elements. And a plurality of terminals electrically connected to each of the light emitting elements, and the light emitting element array chip 3 has a conventionally known face-down bonding, that is, the terminals are made of an anisotropic conductive adhesive, solder, or the like. It is mounted on one main surface of the transparent substrate 2 by being electrically connected to the power supply wiring via a conductive adhesive.
[0015]
The light emitting elements of the light emitting element array chip 3 function to selectively emit light based on the print data when electric power is supplied from the outside via the circuit wiring or the terminals of the light emitting element array chip 3. A predetermined latent image is formed on the photoconductor P by irradiating the emitted light to an external photoconductor P through the transparent substrate 2 or a lens 8 described later.
[0016]
As the light emitting element of the light emitting element array chip 3, for example, a GaAsP light emitting diode element, a GaP light emitting diode element, or the like is used, and these are manufactured by adopting a conventionally well-known semiconductor manufacturing technique. The
[0017]
On the other hand, the driver IC 4 mounted together with the light emitting element array chip 3 on one main surface of the transparent substrate 2 is integrated with a switching transistor, a latch, a shift register, etc. An input / output terminal is provided, and the light emission of the light emitting element is individually controlled based on print data from the outside.
[0018]
This driver IC 4 also has a well-known face-down bonding, that is, the input / output terminals on the upper surface of the driver IC 4 via a conductive adhesive such as an anisotropic conductive adhesive or solder, similarly to the light emitting element array chip 3 described above. It is mounted on one main surface of the transparent substrate 2 by being electrically connected to the power supply wiring and the signal wiring.
[0019]
A metal plate 5 connected to the ground potential (GND) is placed on one main surface of the head substrate 1 so as to cover the signal wiring on the main surface.
[0020]
The metal plate 5 has a rectangular hole 5a corresponding to the outer shape of the driver IC 4, and the driver IC 4 is disposed in the hole 5a.
[0021]
Therefore, the driver IC 4 is surrounded by a grounded metal plate 5.
[0023]
The metal plate 5 is placed on one main surface of the head substrate 1 so as to cover the signal wiring and the like.
[0024]
Further, in this case, since the metal plate 5 is placed in the vicinity of the driver IC 4 mounting portion on one main surface of the head substrate 1, the heat in this region is well absorbed by the metal plate 5 and dissipated into the atmosphere. be able to. Therefore, the temperature state of the head substrate 1 is maintained satisfactorily, whereby the light emission luminance of the light emitting element array chip 3 can be stabilized.
[0025]
Further, the metal plate 5 is processed into a comb-like shape as shown in FIG. 3, and one end face 5c of the metal plate 5 is brought into contact with the side face of the light emitting element array chip 3, and the other end face 5d is brought into contact with an inner wall of the housing 7 described later. By doing so, it is possible to mount a plurality of light emitting element array chips 3 in a line on a line spaced from the inner wall of the housing 7 by a certain distance, thereby positioning each light emitting element array chip 3. This is accurate and simple, and can greatly contribute to the improvement of productivity of the optical printer head. Accordingly, it is preferable that one end surface 5 c of the metal plate 5 is in contact with the side surface of the light emitting element array chip 3 and the other end surface 5 d is in contact with the inner wall of the housing 7.
[0026]
The metal plate 5 is made of, for example, SUS, phosphor bronze, iron or the like having a thickness of about 0.05 mm to 0.2 mm, and a plate body made of these metals is formed into a predetermined shape by a conventionally known etching technique or the like. It is formed with a dimensional accuracy of ± 5 μm.
[0027]
Further, an adhesive (preferably epoxy type or silicon type), double-sided tape or the like is used for fixing the metal plate 5 to the head substrate 1, and a driver IC 4 is disposed in the hole 5 a of the metal plate 5. Thus, the metal plate 5 is fixed to the head substrate 1 by bonding the two with the adhesive.
[0028]
In this case, a positioning projection made of the same material as the circuit wiring and the signal wiring is provided on one main surface of the head substrate 1, and a positioning hole corresponding to the positioning projection is provided in the metal plate 5. This makes it easier to align the two.
[0029]
The metal plate 5 is housed in the housings 6 and 7 together with the head substrate 1.
[0030]
The housings 6 and 7 are composed of a lower region 6 on which the head substrate 1 and the metal plate 5 are placed, and an upper region 7 to which a plurality of lenses 8 are attached. The head substrate 1 and the metal plate 5 are accommodated in a space formed between the region 7.
[0031]
The housings 6 and 7 are made of a relatively inexpensive plastic material or the like, and the housings 6 and 7 serve as a light shielding member that houses the head substrate 1 and the metal plate 5 and shields light from the outside.
[0032]
Each of the lenses 8 attached to the upper region 7 of the housing is a monocular lens, and the lenses 8 are arranged on the respective light emitting element array chips 3 in a one-to-one correspondence.
[0033]
The lens 8 is made of plastic, glass, or the like, and functions to irradiate and image the light of the light emitting element of the corresponding light emitting element array chip 3 to the external photoreceptor P.
[0034]
The housing has a predetermined positioning pin 7a in the upper region 7 and a predetermined positioning hole 6a in the lower region 6. The head substrate 1 and the metal plate 5 are placed on the lower region 6 of the housing. After the mounting, the upper region 7 of the housing to which the plurality of lenses 8 are attached is integrated so that the positioning pins 7a are inserted into the positioning holes 6a, and the head substrate 1 and the metal plate 5 are integrated. Is housed in the housings 6 and 7 to complete an optical printer head as a product.
[0035]
At this time, if a reference hole 5b into which the positioning pin 7a is inserted is provided at the end of the metal plate 5, the lens 8 and the metal plate attached to the upper region 7 of the housing when the optical printer head is assembled. The head substrate 1 fixed to 5 can be easily aligned in the longitudinal direction. The reference hole 5b is preferably positioned on the center line of the light emitting element array 3, and the reference hole 5b is positioned on the center line of the light emitting element array 3 so that the light emitting element array chip 3 The line of the light emitting element and the center line of the lens 8 can be relatively easily matched, and the positional accuracy of the light emitting element array chip 3 and the lens 8 can be greatly improved. Therefore, it is preferable that the reference hole 5 b of the metal plate 5 is located on the center line of the light emitting element array 3.
[0036]
When the optical printer head is assembled by the above-described method, the center of the light emitting element array chip 3 and the center of the lens 8 can be positioned with a positional accuracy of ± 10 μm.
[0037]
In addition, this invention is not limited to the above-mentioned form, A various change, improvement, etc. are possible in the range which does not deviate from the summary of this invention.
[0038]
For example, in the above-described embodiment, a plurality of monocular lenses are used as the lenses 8 attached to the upper region 7 of the housing, but instead of this, a self-focusing lens array in which a large number of rod lenses are arranged in two rows, etc. May be used.
[0039]
In the above embodiment, the LED printer head is configured by applying the light emitting diode element as the light emitting element of the light emitting element array chip 3, but other optical printer heads such as an EL head, a plasma dot head, a liquid crystal shutter head, The present invention can be applied to a fluorescent head, PLZT, and the like.
[0040]
【The invention's effect】
According to the optical printer head of the present invention, the driver IC is surrounded by a grounded metal plate disposed around the driver IC, and the metal plate is mounted near the driver IC mounting portion on one main surface of the head substrate. Therefore, the heat in this region can be absorbed well by the metal plate and dissipated into the atmosphere. Therefore, the temperature state of the head substrate is maintained satisfactorily, whereby the light emission luminance of the light emitting element array chip can be stabilized.
[0042]
Furthermore, according to the optical printer head of the present invention, the metal plate is processed into a comb-like shape, and one end surface on the back side of the metal plate is brought into contact with the side surface of the light emitting element array chip. At the same time, a plurality of light emitting element array chips can be mounted in a line, which makes it possible to position each light emitting element array chip accurately and easily, greatly contributing to the improvement in productivity of the optical printer head.
[0043]
Further, according to the optical printer head of the present invention, the head substrate and the metal plate are accommodated in the housing, and the one end surface of the metal plate is opposed to the one end surface of the light emitting element array chip. By bringing the end face into contact with the inner wall of the housing, a plurality of light emitting element array chips can be mounted in a line along with a driver IC on a line spaced apart from the inner wall of the housing. Positioning of each light emitting element array chip is accurate and simple, and can greatly contribute to the productivity improvement of the optical printer head.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an optical printer head according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of an optical printer head according to an embodiment of the present invention.
3 is a perspective view of a metal plate and a head substrate used in the optical printer head of FIGS. 1 and 2. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Head substrate, 3 ... Light emitting element array chip, 4 ... Driver IC, 5 ... Metal plate, 5a ... Hole part, 6, 7 ... Housing

Claims (2)

A head substrate having a light emitting element array chip in which a large number of light emitting elements are linearly arranged on one main surface and a driver IC for controlling light emission of the light emitting elements mounted on one main surface of the transparent substrate by face-down bonding, and the driver side surface of the light emitting element array chip to one end face of Rutotomoni rear side provided with a hole corresponding to the outer shape of the IC consists of a machined metal plates in a tooth shape as to abut,
The metal plate on one principal surface of the transparent substrate, wherein the driver IC is disposed within the bore, the side surface of the light emitting element array chips were placed in the so that to contact the one end surface An optical printer head characterized by that. Light according to claim 1, characterized in that the end face facing the other end surface of the housing to Rutotomoni the metal plate the head substrate and the metal plate in the interior of the housing is brought into contact with the inner wall of the housing Printer head.

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