JP2004209703A - Optical writing head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical writing head employing an erecting variable magnification lens array capable of forming the image of an array of light emitting points linearly on the surface of a photosensitive drum without relying upon a staggered arrangement. <P>SOLUTION: The optical writing head comprises a plurality of self-scanning light emitting element array chips 1 each having an array 11 of a plurality of light emitting points arranged linearly, and an erecting variable magnification lens array 2 arranged at an operating distance from the chip. The self-scanning light emitting element array chips 1 are arranged at a constant interval such that the arranging direction of the light emitting points becomes the main scanning direction. The erecting variable magnification lens array 2 consists of an erecting constant magnification lens array 20 and a plurality of concave lenses 21. The concave lenses 21 are arranged in contact with each other in order to enlarge a light incoming from the array 11 of light emitting points in the main scanning direction and in contact with the erecting constant magnification lens array 20. The array 11 of light emitting points forms the image 23 of an array of light emitting points enlarged in the main scanning direction on the surface A of a photosensitive drum through the erecting variable magnification lens array 2. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical writing head used in an optical printer, and more particularly, to an optical writing head using an erecting zoom lens array.
[0002]
[Prior art]
In an optical printer, a latent image is formed by irradiating light from a light emitting element linearly arranged on a substrate of an optical writing head to a photosensitive drum through an erecting equal-magnification lens array, and forming the latent image. Printing is performed by developing with toner, transferring the toner to paper, and fixing the toner to paper by heat or the like.
[0003]
FIG. 1 is a cross-sectional view in a direction orthogonal to the main scanning direction of an optical writing head mounted on a conventional optical printer (hereinafter, referred to as a sub-scanning direction). A plurality of light emitting element array chips 31 in which light emitting elements are arranged in a row are mounted on a chip mounting substrate 30 in the main scanning direction, and the light emitting elements of the light emitting element array chips 31 emit light on the optical path of light. An erect, equal-magnification rod lens array 32 elongated in the main scanning direction is fixed by a resin housing 33. A photosensitive drum 34 is provided on the rod lens array 32. Further, a heat sink 35 for releasing heat of the light emitting element array chip 31 is provided on a base of the chip mounting substrate 30, and the housing 33 and the heat sink 35 are fixed with a stopper 36 with the chip mounting substrate 30 interposed therebetween. ing.
[0004]
As the above-described light emitting element array chip, a self-scanning light emitting element array chip is used. The self-scanning light-emitting element array chip is a light-emitting element array chip having a built-in self-scanning circuit and having a function of sequentially transferring light-emitting points.
[0005]
As for the self-scanning light emitting element array chip, Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4, etc. disclose that a light source for a printer head can be easily mounted, a light emitting element interval can be reduced, and a compact printer can be used. It shows that a head can be manufactured. Patent Document 5 proposes a self-scanning light-emitting element array chip having a structure in which a transfer element array is used as a shift section and is separated from a light-emitting element array as a light-emitting section.
[0006]
FIG. 2 shows an equivalent circuit diagram of a self-scanning light emitting element array chip having a structure in which a shift section and a light emitting section are separated. The shift unit includes a transfer element T ₁ , T _Two , T _Three , And the light-emitting section includes a light-emitting element L for writing. ₁ , L _Two , L _Three ,…have. These transfer element and light emitting element are constituted by a three-terminal light emitting thyristor. The structure of the shift unit is such that a diode D is used to electrically connect the gates of the transfer elements to each other. ₁ , D _Two , D _Three , ... are used. V _GK Is a power supply (usually 5 V) and a load resistance R _L Through the gate electrode G of each transfer element. ₁ , G _Two , G _Three ,…It is connected to the. Also, the gate electrode G of the transfer element ₁ , G _Two , G _Three ,... Are also connected to the gate electrode of the light emitting element for writing. Transfer element T ₁ Start pulse φ _S , And transfer clock pulses φ1 and φ2 are alternately applied to the anode electrode of the transfer element, and the write signal φ is applied to the anode electrode of the write light emitting element. _I Has been added.
[0007]
The operation will be briefly described. First, when the voltage of the transfer clock pulse φ1 is at the H level and the transfer element T _Two Is in the ON state. At this time, the gate electrode G _Two Is V _GK 5V to almost zero V. The effect of this potential drop is _Two Gate electrode G _Three To the potential of about 1 V (diode D _Two Is set to the forward rising voltage (equal to the diffusion potential). However, the diode D ₁ Is in a reverse-biased state, so that the gate electrode G ₁ Is not connected to the gate electrode G ₁ Remains at 5V. Since the ON voltage of the light emitting thyristor is approximated by the gate electrode potential + diffusion potential of the pn junction (about 1 V), the H level voltage of the next transfer clock pulse φ2 is about 2 V (the transfer element T _Three ) And about 4 V (the transfer element T). _Five Voltage required to turn on the transfer element). _Three Only the transfer elements can be turned on, and the other transfer elements can be kept off. Therefore, the ON state is transferred by two transfer clock pulses.
[0008]
Start pulse φ _S Is a pulse for starting such a transfer operation, and a start pulse φ _S To the H level (about 0 V) and at the same time the transfer clock pulse φ2 to the H level (about 2 to about 4 V), and the transfer element T ₁ Turn on. Shortly thereafter, the start pulse φ _S Is returned to the H level.
[0009]
Now, the transfer element T _Two Is in the ON state, the gate electrode G _Two Is almost 0V. Therefore, the write signal φ _I Is equal to or higher than the diffusion potential (about 1 V) of the pn junction, the light emitting element L _Two Can be in a light emitting state.
[0010]
On the other hand, the gate electrode G ₁ Is about 5 V and the gate electrode G _Three Is about 1V. Therefore, the light emitting element L ₁ Is about 6 V, and the light emitting element L _Three Is about 2V. From now on, the light emitting element L _Two Write signal φ that can be written only to _I Is in the range of 1-2V. Light emitting element L _Two Is turned on, that is, when the light emitting state is entered, the light emission intensity becomes equal to the write signal φ. _I Is determined by the amount of current flowing through the device, and an image can be written at an arbitrary intensity. In order to transfer the light emitting state to the next light emitting element, the write signal φ _I It is necessary to once reduce the voltage of the line to 0 V and turn off the light emitting element that emits light.
[0011]
When applying a self-scanning light emitting element array to an optical writing head, etc., a plurality of light emitting element array chips are arranged in one direction, and when outputting an image, image data on the memory is synchronized with desired timing. Then, the light is transferred to the corresponding light emitting element on the light emitting element array chip to cause the light emitting element to emit light.
[0012]
Such a self-scanning light emitting element array is characterized in that fewer bonding pads are required as compared with a normal light emitting element array. With this feature, the chip area can be reduced, and low cost can be realized. Furthermore, if the bonding pads are arranged at both ends of the rectangular chip, the chip width can be reduced to a width almost required by the bonding pads themselves. However, when applied to an optical writing head, if a plurality of chips are arranged in one direction, the distance between light emitting points (light emitting elements) at the chip ends cannot be made constant. In order to avoid this, there is a so-called staggered arrangement method in which chips are partially overlapped and arranged (see Patent Document 6).
[0013]
FIG. 3 is a diagram showing this staggered arrangement method. For convenience of explanation, it is assumed that xy coordinate axes are determined as shown. That is, the x-axis direction is a chip arrangement direction (main scanning direction), and the y-axis direction is a direction (sub-scanning direction) orthogonal to the chip arrangement direction. The self-scanning light-emitting element array chip 39 has bonding pads 40 provided at both ends, and light-emitting points 41 formed of light-emitting elements are linearly provided therebetween.
[0014]
Such a light emitting element array chip 39 is displaced in the y-axis direction and both ends of the chip are overlapped and arranged in a staggered manner in the x-axis direction. Distance x from point ₁ , X _Two , X _Three Are set equal to p, so that the distance between the light emitting points in the x-axis direction is set to a constant value p throughout all of the plurality of chips.
[0015]
The light emitting points on each self-scanning light emitting element array chip are turned on one by one sequentially from the leftmost light emitting point. An image is written by turning on each light emitting point at the shifted timing.
[0016]
[Patent Document 1]
JP-A-1-238962
[Patent Document 2]
JP-A-2-14584
[Patent Document 3]
JP-A-2-92650
[Patent Document 4]
JP-A-2-92651
[Patent Document 5]
JP-A-2-263668
[Patent Document 6]
JP-A-8-216448
[Patent Document 7]
JP 2000-284217 A
[0017]
[Problems to be solved by the invention]
However, when a light emitting point array image is projected on the photosensitive drum using an optical writing head in which the light emitting element array chips are staggered, the light emitting point array image on the photosensitive drum surface is displaced in the y-axis direction. , A shift in the y-axis direction (step), and as a result, a step corresponding to the shift width of the chip also occurs in the output image.
[0018]
Therefore, in a staggered light-emitting element array chip, image data is called from an image memory for each chip, and the timing of transferring the image data to the corresponding light-emitting element on the chip is adjusted, so that the chip is formed on the photosensitive drum surface. The deviation of the light emitting point sequence image in the y-axis direction is corrected.
[0019]
Therefore, in an optical writing head in which the light emitting element array chips are arranged in a staggered manner, an extra memory for compensating for the deviation is required.
[0020]
Further, the rod lens array has a large variation in the light amount distribution near the end in the sub-scanning direction, and a small variation in the light amount distribution near the center in the sub-scanning direction. Therefore, in order to use an area having a small variation in the light amount distribution, the chip cannot be shifted too much in the sub-scanning direction.
[0021]
In order to prevent the chip from being largely displaced in the sub-scanning direction, as shown in FIG. The distance L from the center line of the light emitting point array must be as small as possible. For that purpose, when dicing a chip from a semiconductor wafer on which a large number of light emitting element array chips are formed, the light emitting point array has Need to cut near place. However, if chipping occurs in the cutting chip while cutting a location very close to the light emitting point sequence, the chipping may reach the light emitting point and damage the light emitting point. As a result, the yield of chip manufacturing is reduced. There is also a method of reducing the cutting speed in order to suppress chipping, but on the other hand, there is a problem that the cutting time is likely to be long.
[0022]
In addition, since the light emitting point array must be provided at the end of the chip in the sub-scanning direction along the main scanning direction, there is a restriction on the chip design.
[0023]
The present invention has been made in view of such a conventional problem, and an object of the present invention is to form a light emitting point sequence image on a photosensitive drum surface without using a staggered arrangement method requiring an extra memory. An object of the present invention is to provide an optical writing head using an erecting zoom lens array that can be formed linearly.
[0024]
[Means for Solving the Problems]
The present invention provides a plurality of light emitting element array chips having a light emitting point array including a plurality of light emitting points arranged in a straight line, and a light emitting element array chip disposed on a light emitting side of the light emitting element array chip at a working distance from the light emitting element array chip. An optical writing head comprising an erecting variable-magnification lens array, wherein the light-emitting element array chips are arranged at regular intervals so that the arrangement direction of the light emitting points is the main scanning direction, and the erecting variable-magnification lens array is The erecting equal-magnification lens array and a plurality of concave lenses are provided, and each concave lens is provided on the light emission side of the erecting equal-magnification lens array so as to enlarge light emitted from the light emitting point array in the main scanning direction. And are arranged linearly in the main scanning direction.
[0025]
It is preferable that the arrangement interval of the concave lenses in the main scanning direction is equal to the length of the light emitting point sequence image formed on the photosensitive drum surface by the light emitting point sequence for one chip provided on the light emitting element array chip. And the center line of the lens surface of the concave lens may be shifted from each other in the main scanning direction.
[0026]
Further, since the arrangement interval of the concave lenses in the main scanning direction is shorter than the length of the light emitting point sequence image formed on the photosensitive drum surface for the light emitting point sequence for one chip provided on the light emitting element array chip, the light emitting point sequence image When the light emitting point array of the juxtaposed light emitting element array chips overlaps with the end of the light emitting point sequence image formed on the photosensitive drum surface, the light emitting point for projecting the light emitting point image of the overlapping unnecessary portion. Is preferably not turned on.
[0027]
Also, the present invention provides a plurality of light emitting element array chips having a light emitting point array composed of a plurality of light emitting points arranged in a straight line, and a light emitting side of the light emitting element array chip at a working distance from the light emitting element array chip. An optical writing head including an arranged erecting variable-magnification lens array, wherein the light-emitting element array chips are arranged at regular intervals such that the direction of arrangement of light-emitting points is the main scanning direction, and the erecting variable-magnification lens array is provided. Is provided with a spherical lens group composed of minute spherical lenses having different lens pitches on one surface and the other surface on both surfaces, and further includes a plurality of resin lens arrays in which the spherical lens groups are arranged at regular intervals in the main scanning direction. The light emitting device is characterized in that the light emitting points are arranged so as to be enlarged in the main scanning direction.
[0028]
The spacing between the spherical lens groups in the main scanning direction is preferably equal to the length of the light emitting point sequence image formed on the photosensitive drum surface by the light emitting point sequence for one chip provided on the light emitting element array chip. Since the arrangement interval of the groups in the main scanning direction is shorter than the length of the light emitting point sequence image formed on the photosensitive drum surface by the light emitting point sequence for one chip provided on the light emitting element array chip, the end of the light emitting point sequence image However, when the light emitting point sequence of the juxtaposed light emitting element array chip overlaps the end of the light emitting point sequence image formed on the photosensitive drum surface, the light emitting point that projects the light emitting point image of the overlapping unnecessary part is lit. It is preferred not to let it.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0030]
FIG. 4 is a perspective view showing an optical system of the optical writing head according to the first embodiment of the present invention. The optical writing head shown in FIG. 4 includes a plurality of self-scanning light emitting element array chips 1 linearly arranged in a main scanning direction at regular intervals on a head substrate (not shown), and a self-scanning light emitting element array. On the light emission side of the chip 1, there is provided an erecting variable-magnification lens array 2 arranged at a working distance from the chip such that the longitudinal direction is the main scanning direction. On the light emission side of the erecting variable-magnification lens array 2, a photosensitive drum is arranged at the focal position of the lens.
[0031]
The self-scanning light-emitting element array chip 1 includes a light-emitting point array 11 composed of a plurality of light-emitting points (light-emitting elements) linearly arranged at regular intervals on the chip. It is in the scanning direction. Further, a plurality of bonding pads 12 are provided at one end of the chip in the main scanning direction. The bonding wire 12 is connected to the bonding pad 12. A write signal (φ) is sent to the self-scanning light emitting element array chip 1 through the bonding wire 10. _I Signals), transfer clock signals (φ1, φ2 signals), and power.
[0032]
The light emitting point sequence 11 on the chip is projected onto the photosensitive drum surface A via the erecting variator lens array 2 to form a light emitting point sequence image 23 enlarged on the photosensitive drum surface A in the main scanning direction.
[0033]
The erecting variable-magnification lens array 2 includes an erecting equal-magnification lens array 20 and a plurality of concave lenses 21, and each concave lens 21 is emitted from the light emitting point array 11 to the light emission side of the erecting equal-magnification lens array 20. The light is arranged in contact with each other so as to expand the light in the main scanning direction, and further provided in contact with the erecting equal-magnification lens array 20.
[0034]
The erecting equal-magnification lens array 20 may be composed of a plurality of erecting equal-magnification lenses, like the concave lens 21. Further, in FIG. 4, the length of the concave lens 21 in the main scanning direction is equal to the arrangement interval (repetition pitch) of the concave lenses 21. Therefore, the concave lenses 21 are disposed in contact with each other. However, a gap may be left. Since the erecting variable-magnification lens array is used to expand the light emitted from the light-emitting point array in the main scanning direction, at least an area where light from the light-emitting point array of the erecting variable-magnification lens array is incident, It is sufficient that a concave lens having the function of expanding light and an erecting equal-magnification lens are provided. In addition, the concave lens 21 does not necessarily need to be provided in contact with the erecting equal-magnification lens array 20, and may have a gap as long as it can be optically adjusted.
[0035]
As the erecting equal-magnification lens array 20, a rod lens array or an erecting equal-magnification resin lens array is used. The rod lens array is a two-dimensional array of a number of refraction-distribution type rod lenses whose refractive index decreases from the central axis toward the periphery. Can be. An erecting equal-magnification resin lens array is formed by stacking two or more resin lens arrays in which minute spherical lenses having the same focal length and aperture are formed on both sides or one side, and forms an erecting equal-magnification image. Can be done.
[0036]
The concave lens 21 is a part of the side surface of the cylinder, and can change the direction of light by refracting the light emitted from the erecting equal-magnification lens array 20 so as to expand in the main scanning direction. The arrangement interval (repetition pitch) of the concave lenses 21 in the main scanning direction is equal to the length of the light emitting point sequence image 23 formed on the photosensitive drum surface A by the light emitting point sequence 11 for one chip of the self-scanning light emitting element array chip 1. Are chosen to be equal.
[0037]
The distance between the light-emitting points on the self-scanning light-emitting element array chip 1, the size of the light-emitting points, and the magnification of the concave lens are set so that the light-emitting point images formed on the photosensitive drum surface A have the desired distance and size. To be elected.
[0038]
In the self-scanning light emitting element array chip 1, the center of the light emitting point array 11 on the chip (between the 128th and 129th light emitting points when the number of light emitting points is 256) is the lens surface of the concave lens 21. Are arranged so as to coincide with the center line B. FIG. 5 is a diagram showing a state in which the center of the light emitting point sequence is arranged so that the center line B of the concave lens surface is coincident. C and D in the figure are concave lens boundary lines. By arranging in this manner, even if chips having portions that do not emit light, such as bonding pads, are arranged in a line, the light emitting point sequence images 23 can be arranged without any gap on the photosensitive drum surface. That is, the light emitting point images formed on the photosensitive drum surface can all be linearly arranged at equal intervals.
[0039]
Here, the case where the center of the light emitting point array 11 on the chip and the center line B of the lens surface of the concave lens 21 are arranged has been described, but the arrangement interval (repetition pitch) of the concave lens in the main scanning direction is described. Are selected so that the light emitting point array 11 for one chip of the self-scanning light emitting element array chip 1 is equal to the length of the light emitting point array image 23 formed on the photosensitive drum surface, and the interval between the chip arrangements is set to this concave lens. Is equal to the arrangement interval (repeated pitch) of the light emitting point array on the photosensitive drum surface even if the center of the light emitting point array 11 and the center line B of the lens surface of the concave lens 21 are slightly shifted in the main scanning direction. The images 23 can be arranged without gaps. FIG. 6 is a diagram showing a state in which the center of the light emitting point sequence and the center line B of the concave lens surface are shifted from each other in the main scanning direction. In other words, the alignment accuracy between the chip and the lens is reduced according to the magnification of the concave lens. Therefore, sufficient alignment accuracy can be ensured only by mechanically assembling the chip and the lens into the head.
[0040]
Since the light is enlarged only in the main scanning direction using the concave lens, the light emission point image formed on the focal plane is distorted. However, assuming that the length of the bonding pad portion is 0.45 mm and the light emitting point array having a length of 5.0 mm on the chip is enlarged to 5.461 mm, the enlargement ratio is only 9.2%. The curvature of the light-emitting point image formed on the focal plane does not matter much.
[0041]
According to the optical system of the present embodiment, the length of the light-emitting element array chip is reduced by about 10%, and it is not necessary to cut off a portion very close to the light-emitting point array. Improved.
[0042]
Next, a description will be given of a second embodiment of the optical writing head according to the present invention. FIG. 7 is a diagram illustrating an optical system of an optical writing head according to a second embodiment of the present invention.
[0043]
In the second embodiment, the end portions of the light emitting point sequence images projected on the photosensitive drum surface overlap each other. For example, 132 light-emitting points are formed in a light-emitting point array having a length of 5.0 mm on the chip, and are set to 42.3 μm (600 dpi) × 132 = 5.55836 mm on the surface of the photosensitive drum. Enlarge and project. However, since the arrangement interval (repetition pitch) of the concave lenses is 5.461 mm for 128 light emitting points, when all 132 light emitting points are turned on, two light emitting point images overlap each other at the end. Therefore, by not turning on the light emitting points that project the light emitting point images of the overlapping unnecessary portions, the light emitting point sequence images can be arranged on the photosensitive drum surface without gaps.
[0044]
With such a configuration, even if the alignment accuracy between the chip and the lens in the main scanning direction cannot be ensured, the deviation of the light emitting point in the main scanning direction can be electrically corrected. That is, it corresponds to the image data depending on whether the 1st to 128th light emitting points are selected from the 132 light emitting points on the chip, the 5th to 132nd light emitting points are selected, or the 128 light emitting points between them are selected. The light emitting point sequence image can be moved in parallel on the photosensitive drum surface.
[0045]
Next, a third embodiment of the optical writing head of the present invention will be described. In the first and second embodiments, the erecting zoom optical system is realized by the erecting equal-magnification lens array and the concave lens. However, the erecting zoom optical system has a spherical lens on one surface and the other surface. An erect variable-magnification lens array having a structure in which resin lens arrays with different pitches are stacked in several layers may be used.
[0046]
FIG. 8 is a cross-sectional view along the main scanning direction showing the optical system of the optical writing head according to the third embodiment of the present invention. The optical system of the optical writing head shown in FIG. 8 includes a plurality of self-scanning light-emitting element array chips 1 linearly arranged at regular intervals in a main scanning direction on a head substrate (not shown). On the light emission side of the light-emitting element array chip 1, an erect variable-magnification lens array 3 is disposed at a working distance from the chip such that the longitudinal direction is the main scanning direction.
[0047]
The erecting variable-magnification lens array 3 is provided with a spherical lens group composed of minute spherical lenses having different lens pitches on one surface and the other surface on both surfaces, and furthermore, the spherical lens group is arranged at regular intervals in the main scanning direction. It is configured by stacking a plurality of resin lens arrays to be arranged. Further, the erecting variable-magnification lens array 3 is arranged so as to enlarge the light emitted from the light emitting point array on the light emitting element array chip 1 in the main scanning direction. The arrangement interval of the spherical lens groups in the main scanning direction is selected so that the light emitting point array of one chip of the light emitting element array chip 1 is equal to the length of the light emitting point array image formed on the photosensitive drum surface.
[0048]
FIG. 9 is a partial sectional view of the erecting zoom lens array. In the present embodiment, the erect variable-magnification lens array 3 has three resin lens arrays 22 each having a spherical lens group composed of minute spherical lenses having different lens pitches on one surface and the other surface. It is configured. The pitch of the opposing spherical lenses of the adjacent resin lens arrays is the same.
[0049]
In the present embodiment, as described above, the erecting variable-magnification lens array is formed by stacking three resin lens arrays, and six spherical lenses are arranged on one optical axis. However, in order to form an erect variable-magnification image, at least three spherical lenses need only be on one optical axis. In this erect variable power lens array, the arrangement pitch of the spherical lenses is adjusted so that the optical axes formed by three or more spherical lenses are connected at the same point (intersecting point).
[0050]
The resin lens array 22 can be manufactured by molding (for example, resin molding, 2P molding, injection molding, or the like) a resin material such as an acrylic resin, and minute spherical lenses on both surfaces are formed in an XY matrix. Are arranged in large numbers.
[0051]
FIG. 10 is a plan view (a) of one resin lens array and a cross-sectional view (b) in the Y direction. Spherical lenses 28 are arranged on one surface of a long rectangular acrylic resin plate in an XY matrix at a predetermined pitch, and spherical lenses 29 are arranged on the other surface at a predetermined pitch different from the pitch of the spherical lenses 28. They are arranged in an XY matrix.
[0052]
The self-scanning light-emitting element array chip 1 has the same configuration as that of the first and second embodiments, and includes a plurality of light-emitting points (light-emitting elements) linearly arranged at regular intervals on the chip. And a plurality of bonding pads at one end in the main scanning direction of the chip. The light emitting point sequence on the chip is projected onto a photosensitive drum (not shown) via the erecting zoom lens array 3 to form a light emitting point sequence image enlarged in the main scanning direction on the photosensitive drum surface. This is the same as the first and second embodiments.
[0053]
In the above-described embodiment, the arrangement interval of the spherical lens groups in the main scanning direction is set so that the light emitting point array for one chip of the light emitting element array chip 1 is equal to the length of the light emitting point array image formed on the photosensitive drum surface. The selected spacing between the spherical lens groups in the main scanning direction is shorter than the length of the light emitting point sequence image formed by the light emitting point sequence for one chip of the light emitting element array chip 1 on the photosensitive drum surface. The end of the image may overlap the end of the light emitting point sequence image formed on the photosensitive drum surface by the light emitting point array of the light emitting element array chips arranged side by side. Similarly to the second embodiment, by not turning on the light emitting points that project the light emitting point images of the overlapping unnecessary portions, the light emitting point sequence images can be arranged on the photosensitive drum surface without gaps.
[0054]
Further, in the above-described embodiment, the resin lens array includes the spherical lens groups arranged at regular intervals on both surfaces, but without any space in the main scanning direction, one surface is formed on both surfaces. A spherical lens having a different lens pitch between the and the other surface may be continuously provided in the main scanning direction.
[0055]
As described in the first, second, and third embodiments, the optical writing head using the erecting variable-magnification lens array in the optical system can shorten the length of the light-emitting element array chip. A light emitting point array image can be formed linearly on the photosensitive drum surface without using a staggered arrangement that requires an extra memory, and it is not necessary to cut the light emitting point row immediately adjacent to the light emitting element array chip. In the manufacturing process, the yield can be improved.
[0056]
Further, since the yield of the chip is improved, the cost of the optical printer can be reduced by applying the optical writing head according to the first, second, and third embodiments to the optical printer.
[0057]
In the above-described embodiment, the self-scanning light-emitting element array chip is used as the light-emitting element array chip. However, the present invention is not limited to the self-scanning light-emitting element array chip. Is also applicable.
[0058]
【The invention's effect】
As described above, according to the present invention, since the length of the light emitting element array chip can be shortened, the light emitting point array image can be formed on the photosensitive drum surface without using a staggered arrangement method requiring an extra memory. Can be formed in a straight line, and furthermore, it is not necessary to cut the vicinity of the light emitting point sequence, so that the yield can be improved in the chip manufacturing process.
[Brief description of the drawings]
FIG. 1 is a sectional view in the sub-scanning direction of an optical writing head mounted on a conventional optical printer.
FIG. 2 is an equivalent circuit diagram of a self-scanning light-emitting element array chip having a structure in which a shift unit and a light-emitting unit are separated.
FIG. 3 is a diagram showing a staggered arrangement method.
FIG. 4 is a perspective view showing an optical system of the optical writing head according to the first embodiment of the present invention.
FIG. 5 is a diagram showing a state in which the center of the light emitting point sequence and the center line B of the concave lens surface are arranged to coincide with each other.
FIG. 6 is a diagram showing a state in which the center of a light emitting point array and a center line B of a concave lens surface are shifted from each other.
FIG. 7 is a diagram illustrating an optical system of an optical writing head according to a second embodiment of the present invention.
FIG. 8 is a diagram illustrating an optical system of an optical writing head according to a third embodiment of the present invention.
FIG. 9 is a partial cross-sectional view showing an erect variable power lens array.
FIG. 10 is a plan view and a sectional view of one resin lens array.
[Explanation of symbols]
1,39 Self-scanning light emitting element array chip
2,3 erect zoom lens array
10 Bonding wire
11 Emission point sequence
12,40 bonding pad
20 Erect equal-magnification lens array
21 concave lens
22 resin lens array
23 Emission point sequence image
28,29 spherical lens
30 chip mounting board
31 Light emitting element array chip
32 rod lens array
33 resin housing
34 Photosensitive drum
35 heat sink
36 Clasp
41 luminous point
A Photosensitive drum surface
B concave lens center line
C, D concave lens boundary

Claims (11)

A plurality of light-emitting element array chips having a plurality of light-emitting point arrays composed of a plurality of light-emitting points arranged in a straight line; and an erecting element disposed on the light-emitting side of the light-emitting element array chips at a working distance from the light-emitting element array chips. An optical writing head including a double lens array,
The light emitting element array chips are arranged at regular intervals such that the arrangement direction of the light emitting points is the main scanning direction,
The erecting variable-magnification lens array includes an erecting equal-magnification lens array and a plurality of concave lenses.Each concave lens is provided on the light emission side of the erecting equal-magnification lens array, and is emitted from the light emitting point array. An optical writing head, wherein the light is arranged linearly in the main scanning direction such that the light is enlarged in the main scanning direction. The said concave lens is provided in contact with the erecting equal-magnification lens array on the light emission side of the erecting equal-magnification lens array, and is arranged linearly in contact with each other in the main scanning direction. An optical writing head according to item 1. 2. The arrangement interval of the concave lenses in the main scanning direction is equal to a length of a light emitting point sequence image formed on a photosensitive drum surface by a light emitting point sequence for one chip provided on the light emitting element array chip. Or the optical writing head according to 2. 4. The optical writing head according to claim 3, wherein a center of the light emitting point sequence and a center line of a lens surface of the concave lens are displaced in the main scanning direction. 5. The arrangement interval of the concave lenses in the main scanning direction is shorter than the length of the light emitting point sequence image formed on the photosensitive drum surface by the light emitting point sequence for one chip provided on the light emitting element array chip. When the light emitting point array of the juxtaposed light emitting element array chip overlaps the end of the light emitting point sequence image formed on the photosensitive drum surface, the light emitting point that projects the light emitting point image of the overlapping unnecessary part is turned on. 3. The optical writing head according to claim 1, wherein the optical writing head is not operated. The optical writing head according to claim 1, wherein the erecting equal-magnification lens array is a rod lens array or an erecting equal-magnification resin lens array. A plurality of light-emitting element array chips having a plurality of light-emitting point arrays composed of a plurality of light-emitting points arranged in a straight line; and an erecting element disposed on the light-emitting side of the light-emitting element array chips at a working distance from the light-emitting element array chips. An optical writing head including a double lens array,
The light emitting element array chips are arranged at regular intervals such that the arrangement direction of the light emitting points is the main scanning direction,
The erect variable power lens array includes spherical lens groups on both sides, each of which has a minute spherical lens having a different lens pitch on one surface and the other surface, and further includes a spherical lens group at a constant arrangement interval in the main scanning direction. An optical writing head comprising a plurality of resin lens arrays to be arranged, wherein the resin lens arrays are arranged so as to expand light emitted from the light emitting point array in a main scanning direction. The arrangement interval of the spherical lens groups in the main scanning direction is equal to the length of a light emitting point sequence image formed on a photosensitive drum surface by a light emitting point sequence for one chip provided on the light emitting element array chip. Item 8. The optical writing head according to Item 7. The arrangement interval of the spherical lens group in the main scanning direction is shorter than the length of the light emitting point sequence image formed on the photosensitive drum surface by the light emitting point sequence for one chip provided on the light emitting element array chip. When the light emitting point array of the juxtaposed light emitting element array chips overlaps with the end of the light emitting point sequence image formed on the photosensitive drum surface, the light emitting point projecting the light emitting point image of the overlapping unnecessary portion The optical writing head according to claim 7, wherein is not turned on. 10. The optical writing head according to claim 1, wherein the light emitting element array chip is a self-scanning light emitting element array chip. An optical printer comprising the optical writing head according to claim 1.

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