JPH07156445A - Light source device for optical printer - Google Patents

Abstract

PURPOSE:To increase a degree of freedom in positional regulation between an optical system and a light emission diode by a method wherein an optical path setting means or the like which sets an exposed dot so as to be formed at a practically same position for each light emission diode, is provided. CONSTITUTION:A mirror 205 makes a second group light beam 212 incident upon an RMLA 206c by following a path different from a path of a first group light beam 211. The second group light beam 212, after successively passing through a lens 206a and a stop 206b, impinges on the roof mirror 206c, and is successively reflected on a pair of adjacent roof reflecting surfaces composing the roof mirror array 206c. Then, it passes in a reverse didrection to that at light-successively incident time through the stop 206b and the lens 206a, and is focused on a sensitizing material 250. Since the sensitizing material 250 is exposed to light by both of the light beam emitted from a front end surface of an LED chip 203 and the light beam 212 emitted from an upper principal surface of the chip 203, its luminous efficacy is extremely improved by being compared with that of an optical line printing head.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a light source device used for an optical print head of a printer or a copying machine, and more particularly to a light source device using a light emitting diode suitable for an optical line print head.

[0002]

2. Description of the Related Art In an electrophotographic printer, an image is recorded on a recording paper by a light beam. More specifically,
The image to be recorded is drawn as an electrostatic latent image by irradiating a photoconductor such as a photosensitive drum or photosensitive belt with a light beam, and the electrostatic latent image thus formed is developed with toner to form a toner image. It is formed. By transferring the toner image formed on the photoconductor to the recording paper, a desired image is recorded on the recording paper.

Therefore, such an electrophotographic printer requires a powerful and highly reliable light source device for forming a light beam. In particular, in order to record a desired image at high speed and with high resolution, the light source device is generally composed of an optical semiconductor device that can simultaneously generate a plurality of light beams. Typically, a semiconductor laser or a light emitting diode is used as the light source device, but the cost of using the light emitting diode is lower than that of using the semiconductor laser.

In general, a plurality of laser diodes are formed in an array on a single laser diode chip, and a plurality of light beams formed by these laser diode arrays are deflected by a rotating polygon mirror or the like so as to be reflected on the surface of the photoconductor. To scan. In addition, it is also practiced to form an optical line print head by arranging light emitting diode chips in which a light emitting diode array formed of a plurality of light emitting diodes is arranged in a line. In such an optical line printhead, a plurality of light beams are formed at substantially the same time corresponding to main scanning lines.
The optical line print head does not require a movable part such as a rotary polygon mirror and a driving part therefor, and thus the printer can be downsized.

FIG. 14 is a perspective view showing a structure of a conventional optical line print head disclosed in Japanese Patent Laid-Open No. 60-1146479, and FIG. 15 is a perspective view showing a structure of a light emitting diode array used in the optical line print head of FIG. is there.

Referring to FIG. 14, the optical line print head is constructed on a heat sink 102 formed on a base 101, and a plurality of light emitting diodes held on a ceramic wiring substrate 103 provided on the heat sink 102. Chip 104 and corresponding wiring board 10 corresponding thereto
3 includes a plurality of drive integrated circuit chips 105 provided on the same. The substrate 103 has an elongated shape extending in the main scanning direction of the optical line print head, and has the light emitting diode chip 1
04 are arranged along the front edge of the wiring substrate 103 in the main scanning direction. Each light emitting diode chip 104
Carries a plurality of light emitting diodes along the front edge, and each light emitting diode outputs an output light beam in front of its end face in response to an image signal supplied to a drive integrated circuit 105 via a cable 107. To do. Each output light beam has a load lens array 108 that constitutes an equal-magnification imaging system.
Incident on the photoconductor (FIG. 16).
Focus) as indicated by the arrow above. At this time, in order to align the optical axis level of the road lens array 108 and the optical axis of the light emitting diode on the light emitting diode chip 104, an adjusting member 109 is provided below the lens array 108.

FIG. 15 shows an example of the light emitting diode chip 104.
It is an enlarged view showing a part. On the LED chip 104
Has a plurality of light emitting diodes 1 separated from each other by a separation groove.
04 ₁, 104₂, 104₃Are formed, and each
The light emitting diode has a front end face 104a, and the light beam is an arrow.
It is output to the front through the front end face 104a as indicated by the mark.
It An electrode 10 is provided on the upper main surface of each light emitting diode.
4b is formed, and the driving integrated circuit 105 is formed on the electrode 104b.
The drive signal is output from the output signal pad 105a formed above.
It is supplied through the bonding wire 106.

[0008]

FIG. 16 is a diagram showing focusing of the light beam output from the light emitting diode 104 ₁ on the light emitting diode chip 104 onto the photoconductor 150 by the road lens array 108. In the light emitting diode 104 ₁ , the light beam is formed in the active layer. To efficiently focus the light beam thus formed on the photoconductor 150, the optical axis of the light emitting diode, that is, the light emitting diode is formed. The level of the active layer in 104 and the optical axis of the lens array 108 must be exactly aligned. If the two are deviated, there arises a problem that the exposure amount on the photoconductor 150 becomes uneven. For this reason, in the configuration of FIG. 14, the adjusting member 109 is provided below the road lens array 108, but such a configuration requires a high degree of processing accuracy, and nevertheless the lens array 108 has a substantial optical loss. Inevitable inside.

On the other hand, conventionally, the road lens array 10 has been used.
The use of a roof mirror lens array (hereinafter abbreviated as RMLA) has been proposed as an alternative optical imaging system to the V.8. For example, OPTRONICS, No. 1, pp102
-110, 1993 or PlusE, No. 15
9, February 1993 issue.

FIG. 17 shows the configuration of such a known RMLA. Referring to FIG. 17, the RMLA basically includes a high-density lens array 111 including a plurality of lenses arranged repeatedly at a predetermined pitch in the Y direction corresponding to the main scanning line direction of the optical print head, and A roof mirror array 112 having a roof-type reflecting surface repeatedly formed at a pitch corresponding to the pitch of the lenses in the lens array 111 in the Y direction, and light rays representing images A, B, ... After passing through the respective lenses forming the lens array 111 in the direction of approximately -X as indicated by the arrow,
The light enters the roof mirror array 112. The light rays that have entered the roof mirror array 112 in this manner are sequentially reflected by the pair of roof-type reflecting surfaces that form the roof mirror array 112, change their traveling directions, and are emitted in approximately the X direction. The light rays emitted from the roof mirror array 112 pass through the lens array 111 again, and are then deflected in the Z direction by the optical path separation mirror 113 provided in the optical path, and the images A, B, ... The image corresponding to is formed as an erect real image on the image plane conjugate with the object plane as shown by the broken line.

In the RMLA having such a structure, as described above, the roof type reflecting surface forming the roof mirror array 112 is repeatedly formed in the Y direction, and the lenses forming the lens array 111 are correspondingly formed. Since the images are repeatedly formed in the Y direction, the images A, B, ...
Are imaged overlapping each other in the Y direction. However, RML
A forms an erecting equal-magnification imaging system in the Y direction. So RM
By extending the length of LA in the Y direction, it is possible to form an image along the main scanning line of an arbitrary length.

In the RMLA, the light amount distribution in the Y direction can be set to be substantially constant by matching the pitches of the lens array 111 and the roof mirror array 112 in the Y direction. The RMLA is also suitable as an optical system of an optical line print head because it has a feature that the optical loss is small and the positioning with respect to the light emitting diode that constitutes the light source is not required to be highly accurate. Therefore, the applicant of the present invention previously filed Japanese Patent Application No. 4-14.
9098 and 4-149099 propose an optical print head using RMLA for an optical system.

On the other hand, in the conventional optical print head, since the edge emitting type light emitting diode is used, the light beam can be taken out in only one direction with respect to the light emitting diode array, and therefore the light emitting diode array is formed. The light beam is not used efficiently. An optical print head using a surface emitting type light emitting diode has also been proposed (for example, Proceedings of the 1980 Dentsu Society, pages 1 to 211), but in such a configuration, the light beam emitted from the end face cannot be used and Since an electrode has to be formed on the emitting surface from which the output beam is emitted, it is difficult to perform high-density recording exceeding 600 dpi, for example. Also, in these conventional optical printheads, the size of the light beam obtained from the light emitting diode is constant and cannot be varied. Therefore, when the size of the light beam is changed according to the recording density, the area shielded by the electrodes becomes relatively large as compared with the low density light emitting diode,
The light utilization efficiency is reduced.

In view of the above problems, it is therefore a general object of the present invention to provide a new and useful light source device for an optical printer.

A more specific object of the present invention is to use the RMLA for the image forming element, thereby increasing the degree of freedom in adjusting the positions of the optical system and the light emitting diode. The adjustment is easy and the image forming performance is improved. An object is to provide a light source device for an optical printer.

Another object of the present invention is to use both a light beam emitted in parallel to a laminated surface of a light emitting diode and a light beam emitted in a vertical direction, thereby improving the light utilization efficiency of a light source device for an optical printer. To provide.

Another object of the present invention is to selectively utilize one of a light beam emitted in parallel to the laminated surface of the light emitting diode and a light beam emitted in a direction perpendicular to the laminated surface of the light emitting diode, so as to optimize the resolution corresponding to the image to be recorded. An object of the present invention is to provide a light source device for an optical printer, which is capable of forming a light beam of various sizes.

[0018]

The present invention solves the above-mentioned problems.
A light-emitting diode array having a plurality of light-emitting diodes arranged in at least one row, and an optical means for converging each of the light beams formed by the plurality of light-emitting diodes on a photoconductor are provided. In the light source device for an optical printer, which forms an image as a set of exposure dots on the photoconductor by driving the light emitting diodes, each of the plurality of light emitting diodes is defined by the upper main surface and the end surface to emit the first light beam. The second light beam is emitted from the end surface along the first optical path, and at the same time, the second light beam is emitted from the upper main surface along a second optical path different from the first optical path; the optical means is: the light emitting diode. Of the first and second light beams emitted from each of the plurality of light emitting diodes, the plurality of lenses being repeatedly arranged at a predetermined pitch in the arrangement direction of A lens array for converging each of them on the photoconductor, and a roof-shaped reflecting surface repeatedly formed in the arrangement direction of the light emitting diodes at a pitch corresponding to a predetermined pitch of the plurality of lenses in the lens array. A roof mirror array that sequentially reflects incident light beams on a pair of adjacent roof-type reflection surfaces; and a plurality of light beam paths that are repeatedly formed at a pitch corresponding to the predetermined pitch in the array direction of the light emitting diodes. And a diaphragm plate means for blocking stray light between adjacent lenses; the lens array is configured such that the first and second light beams formed by the light emitting diodes are provided to the roof mirror array. As it enters the roof mirror array through the array and along each optical path after being reflected by the roof mirror array. A roof mirror lens array arranged so as to be converged on the photoconductor through the lens array; and the optical paths of the first and second light beams, the first and second light beams. The above light source device for an optical printer is characterized by including: an optical path setting means for setting each of the light emitting diodes on the photoconductor to form an exposure dot at substantially the same position.

According to the second aspect of the present invention, each of the light emitting diodes is shielded on the end face so as to regulate the size of the first light beam with respect to the arrangement direction of the light emitting diodes. Formed part.

According to a third aspect of the present invention, each of the light emitting diodes controls the size of the second light beam on the upper main surface with respect to the arrangement direction of the light emitting diodes. A light-shielding portion is formed on.

According to a fourth aspect of the present invention, the optical path setting means receives the first light beam emitted from the end face of the light emitting diode, reflects the first light beam, and reflects the first light beam on the roof mirror lens array. First reflecting means for making the light incident, and second reflecting means for making the second light beam emitted from the upper main surface of the light emitting diode incident and reflecting the second light beam to enter the roof mirror lens array. The optical paths of the first and second light beams are relatively deflected, and the first light beam and the second light beam are substantially the same on the photoconductor for each light emitting diode. And a third reflecting means for adjusting so as to form an exposure dot at a position.

According to a fifth aspect of the present invention, the first reflecting means includes a first mirror which receives the first light beam from an end face of the light emitting diode and reflects the first light beam, and the first mirror. A second mirror that receives the first light beam reflected by the mirror and reflects the first light beam toward the roof mirror lens array; and the second reflecting means includes the second mirror. In the second reflecting means, the second mirror directly receives the second light beam from the upper main surface of the light emitting diode and reflects the second light beam to reflect the first light beam toward the roof mirror lens array. It is configured to emit along an optical path different from the optical path of the beam.

According to a sixth aspect of the present invention, the third reflecting means is provided in the optical path of the first light beam and reflects the first light beam emitted from the roof mirror lens array. By deflecting the optical path by
It is composed of a mirror.

According to a seventh aspect of the present invention, the first mirror has an incident surface on which the first light beam emitted from the end surface of the light-emitting diode is incident, the incident surface facing the end surface of the light-emitting diode. A prism member having a reflecting surface for reflecting the first light beam incident on the surface and an emitting surface for emitting the first light beam reflected by the reflecting surface.

According to an eighth aspect of the present invention, the prism member has a light shielding member formed on the incident surface except for a portion where the first light beam is incident from the light emitting diode.

According to a ninth aspect of the present invention, in the reflecting surface of the prism member, the size of the first light beam on the photoconductor is a direction orthogonal to the arrangement direction of the light emitting diodes. It is composed of a cylindrical surface with negative power formed so as to increase.

According to a tenth aspect of the present invention, the prism member is arranged such that the position of the first light beam on the photosensitive member is relative to the second light beam with respect to the arrangement direction of the light emitting diodes. It is movably held in the direction of the emission surface so that it can be displaced in a direction orthogonal to each other.

According to an eleventh feature of the present invention, the optical path setting means is arranged in the optical path of the first light beam,
A cylindrical lens having a negative power is formed so that the size of the first light beam on the photoconductor increases in a direction orthogonal to the arrangement direction of the light emitting diodes. .

According to a twelfth aspect of the present invention, the optical path setting means is disposed in the optical path of the second light beam,
A cylindrical lens having a positive power is formed so that a size of the second light beam on the photoconductor is reduced in a direction orthogonal to an arrangement direction of the light emitting diodes. .

According to a thirteenth aspect of the present invention, in each of the light emitting diodes, a virtual perpendicular line drawn to the upper main surface extends from the roof mirror lens array to the photoconductor. It is provided so as to be substantially orthogonal to the chief ray of the two light beams.

According to a fourteenth aspect of the present invention, each of the light emitting diodes has an electrode on the upper main surface, the electrode having a limited area so as to allow the first and second light beams to pass therethrough. Is configured as follows.

According to a fifteenth feature of the present invention, a light source device for an optical printer is further provided on the optical paths of the first and second light beams, and the light exposure of the first and second light beams is performed. A shutter means for controlling the irradiation of the body is provided.

According to a sixteenth aspect of the present invention, the shutter means causes the first and second light beams to reach the photoconductor simultaneously at a first position and the second light beam at the second position. Is configured to selectively block only the light beam of.

According to a seventeenth aspect of the present invention, the shutter means is a cylindrical lens having a negative power, and the cylindrical lens has the first light when the shutter means is at the first position. Hold so that it is inserted into the optical path of the beam.

[0035]

According to the first feature of the present invention, since the exposure dots formed on the photoconductor are formed by the overlapping exposure of the first and second light beams, the light beams formed by the light emitting diode are not exposed. Utilization efficiency is substantially improved. Further, since the roof mirror lens array is used for focusing the first and second light beams onto the photoconductor, the light loss caused by the optical system can be minimized. Further, with the use of the roof mirror lens array, it is possible to relax the strict requirement regarding optical alignment between the light emitting diode and the optical system.

According to the second and third features of the present invention,
It is possible to compensate for the change in the size of the exposure dot on the photoconductor due to the relative optical path difference between the first and second light beams in the main scanning line direction. For example, when the first light beam is correctly focused on the photoconductor, the second light beam is slightly diffused on the photoconductor, and the size of the exposure dot by the second light beam increases. Will end up. Similarly, when the second light beam is properly focused on the photoconductor, the first light beam is somewhat diffused on the photoconductor, and as a result, the size of the exposure dot by the first light beam is increased. Will increase.
In the second and third features, the sizes of the first and second light beams are restricted in the main scanning line direction by forming a mask member on the light emitting diode, and as a result, the main scanning line direction is controlled. It is possible to make the size of the exposure dots for all light beams uniform.

According to the fourth aspect of the present invention, the optical path setting means is constituted by the first and second reflecting means, and further the third optical path setting means is provided.
By providing the above-mentioned reflection means, it is possible to exactly match the formation positions of the exposure dots by the first and second light beams on the photoconductor in the sub-scanning line direction.

According to the fifth aspect of the present invention, the first reflecting means is formed by the first and second mirrors, and the second mirror is also used as the second reflecting means. The size of the optical system including the RMLA is reduced, and at the same time, the optical path difference between the first and second light beams is reduced as much as possible.

According to the sixth aspect of the present invention, the first reflecting light beam, which follows the path close to the wall surface of the light source device and has a small size in the sub-scanning line direction, constitutes the third reflecting means. The light source device is easily configured by deflecting the light with the mirror.

According to a seventh aspect of the present invention, by making the first mirror a prism member having a large refractive index, the effective optical path length of the first light beam is shortened, It is possible to minimize the difference with the optical path length of the two light beams.

According to an eighth aspect of the present invention, by providing a light blocking member on the incident surface of the prism member,
The second light beam can be removed from the second light beam.

According to the ninth feature of the present invention, by making the reflecting surface of the prism member a cylindrical surface having a negative power, the size of the first light beam is expanded in the sub-scanning direction, It is possible to match the shapes of the first and second light beams on the photoconductor.

According to the tenth feature of the present invention, by holding the prism member so as to be movable in a direction orthogonal to its exit surface, the position of the exposure dot by the first light beam is located on the photoconductor. Displaced in the sub-scanning direction,
It is possible to match the position of the exposure dot by the second light beam.

According to an eleventh feature of the present invention, the first
By inserting a cylindrical lens having a negative power in the optical path of the first light beam, the size of the first light beam in the sub-scanning direction is expanded, and the first light beam on the photoconductor is expanded. It is possible to make the size of the exposure dot by the same as the size of the exposure dot by the second light beam.

According to a twelfth aspect of the present invention, the second
By inserting a cylindrical lens having a positive power in the optical path of the second light beam, the size of the second non-existing beam in the sub-scanning direction is reduced, and the second light beam on the photoconductor is reduced. The size of the exposure dot formed by the beam can be made to match the size of the exposure dot formed by the first light beam.

According to a thirteenth feature of the present invention, the second light beam emitted from the upper main surface of the light emitting diode constitutes the second reflecting means by mounting the light emitting diode at an inclination. The light can be efficiently incident on the second mirror. Further, since the second light beam deflected by the second mirror passes through substantially the central portion of the lenses forming the lens array and is incident on the roof mirror array, optical distortion can be minimized.

According to a fourteenth aspect of the present invention, by forming the electrode on the upper main surface of the light emitting diode as small as possible, a large-sized light beam is emitted from the entire upper main surface of the light emitting diode. Can be extracted as a light beam of.

According to the fifteenth and sixteenth features of the present invention, it is possible to selectively switch the irradiation of the first and second light beams onto the photoconductor by the shutter means. As a result, it becomes possible to switch the size of the exposure dot formed on the photoconductor.

According to the seventeenth feature of the present invention, a cylindrical lens is interlocked with the shutter means, and the cylindrical lens makes the sizes of the first and second light beams coincide with each other on the photoconductor. The exposure amount of the first light beam forming the exposure dot can be switched by the shutter means.

Other objects and features of the present invention will become apparent from the detailed description of the embodiments given below with reference to the drawings.

[0051]

1 is a diagram showing the construction of an optical line print head 200 according to a first embodiment of the present invention. In the following description, the light emitting diode is abbreviated as LED.

Referring to FIG. 1, an optical line print head 200 includes a housing 201 and a housing 20 made of aluminum or the like.
1 has an elongated ceramic substrate 202 that is closely supported and extends in the main scanning line direction, and LED chips 203 are formed on the ceramic substrate 202 in line in the main scanning line direction. On each LED chip 203, there are a plurality of LEs arranged in the main scanning line direction to form an LED array.
D is formed, and each LED is
The light beams forming the light beam 211 of the group are emitted toward the photoconductor 250 arranged in the front in a direction substantially orthogonal to the main scanning line direction and the sub scanning line direction. The first group of light beams 211 emitted in the forward direction is LE on the housing 201.
A mirror 204 arranged in front of the D array deflects the light in a direction substantially orthogonal to the substrate 202, that is, in a direction substantially orthogonal to the upper main surface of the LED, and makes the light incident on another mirror 205 held on the top of the housing 201. On the other hand, the mirror 205 makes the incident first group of light beams 211 incident on the RMLA 206 disposed on the housing 201 in a direction substantially opposite to the photoconductor 250 with respect to the mirror 205.

The RMLA 206 is the lens array 1 of FIG.
A plurality of lenses 2 forming a lens array corresponding to 11
06a, a diaphragm member having a plurality of diaphragm holes 206b corresponding to the respective lenses 206a and arranged behind the lens array, and the roof mirror array 112 of FIG. 17 arranged behind the diaphragm member. Roof mirror array 2
06c, the lens 206a and the aperture hole 306.
b is repeatedly formed at a predetermined pitch in the main scanning direction. Further, in the roof mirror array 206c, similarly to the roof mirror array 112, roof-type reflecting surfaces are repeatedly formed in the main scanning direction at the predetermined pitch. However, the diaphragm member is provided to eliminate stray light between light beams passing through different lenses. In the illustrated example, the RMLA 206 is held on the housing 201 by a holding member 206d.

Therefore, the first beam incident on the RMLA 206c
The light beam 211 of the group is reflected by the lens 206a and the aperture 20.
After passing through 6b one after another, it is successively reflected by a pair of adjacent roof type reflecting surfaces in the roof mirror array 206c, and the aperture hole 2
After passing through 06b and the lens 206a in the direction opposite to the direction of successive incidence, the light is emitted. The light beam 211 emitted from the RMLA 206 is further reflected and deflected by the mirror 207,
It is focused on the photoconductor 850 by the action of the lens 206a.

In the embodiment shown in FIG. 1, the LED chip 2 is used.
Each of the LEDs on the LED 03 has a light beam forming the second group of light beams 212 from the upper main surface thereof in a direction substantially orthogonal to the upper main surface, that is, substantially orthogonal to the substrate 202. To emit in the direction. At this time, the second group of light beams 2 emitted by the mirror 205 described above in this way
It is provided so as to be located on the 12 optical paths, and the mirror 205 transmits the light beam 212 of the second group to the light beam 212 of the first group as in the case of the light beam 211 of the first group, RMLA by following a route different from the route
It is incident on 206c. Therefore, the second group of light beams 21
Reference numeral 2 sequentially passes through the lens 206a and the aperture hole 206b, then enters the roof mirror 206c, and is sequentially reflected by a pair of adjacent roof type reflecting surfaces forming the roof mirror array 206c, and then the aperture hole 206b and the lens 206a.
And is successively focused on the photoconductor 250 by passing through in the opposite direction of the incident direction. In other words, the photoconductor 250 is the LED chip 20.
3 and the light beam 211 emitted from the front end surface of the chip 203.
Compared with the conventional optical line print head that is exposed by both of the light beams 212 emitted from the upper main surface, and as a result, uses only the light beam emitted from the end surface or uses only the light beam emitted from the upper main surface. The exposure efficiency is greatly improved.

In the embodiment shown in FIG. 1, the light beam 211 and the light beam 212 emitted from the same LED are the photosensitive member 2.
Mirror 2 so that it is imaged at the same point on 50
Reference numerals 04 and 207 include adjusting mechanisms 204a and 207a.
Are provided respectively. That is, by tilting the mirrors 204 and 207 as shown by the arrow in FIG. 1, the light beams 211 and 2 as shown by the arrow V in FIG.
The position 12 moves on the photoconductor 250 in the sub-scanning line direction. When the adjustment is complete, the mirrors 204 and 207
Is fixed to the housing 201 with an adhesive or the like.

FIG. 2 shows the LED chip 203 used in FIG.
Shows a part of. In FIG. 2, the LED chip 203 is GaAs
A plurality of LEDs 302 are monolithically formed on the substrate 301 by being separated from each other by a separating groove 311 in the main scanning line direction. More specifically, the substrate 301 is made of n-type GaAs, and the substrate 3
On 01, a buffer layer 321 made of n-type GaAs is formed. A first cladding layer 322 made of n-type AlGaAs is formed on the buffer layer 321, and further, a composition made of undoped AlGaAs and having a smaller bandgap than that of the cladding layer is formed on the first cladding layer 322. The set active layer 323 is formed. A second clad layer 324 made of p-type AlGaAs whose composition is set to have a bandgap larger than that of the active layer 323 is formed on the active layer 323, and the clad layer 324 is further formed on the clad layer 324. 32
4, a current diffusion layer 325 made of p-type AlGaAs having substantially the same composition as that of Example 4 with a higher carrier concentration is formed.
A contact layer 326 made of is formed. An n-type lower electrode 328 is formed on the lower main surface of the substrate 301 substantially over the front surface, and a p-type upper electrode 327 is formed in a limited region on the upper main surface of the contact layer 326.
The LEDs 302 are arranged on the LED chip 203 so that their front end surfaces 302a are aligned, and the upper main surface of the contact layer 326 is aligned with the upper main surface 302b of the LED 302. Further, a layered structure 301c is formed on a portion corresponding to the back of the LED array 302 on the substrate 301, a bonding pad 303 is formed on the layered structure 301c, and a wiring conductor pattern 30 is also formed on the layered structure 301c.
8 is connected to and formed on the electrode 327. Such L
In the ED chip 203, each LED 302 has an electrode 32.
Carriers are injected from 7 and 328 into the active layer 323, and recombination of the injected carriers causes light emission in the active layer 323.

On the one hand, the emitted light is emitted forward from the front end face 302a to form the light beam 211 of the first group,
Further, the light beams 212 of the second group are formed by being emitted substantially vertically from the LED upper main surface 302b. In order not to prevent the emission of the second group of light beams 212, the p
The mold upper electrode 327 has a limited area as described above, and the carrier concentration is increased so that the carriers injected from the electrode 327 are uniformly injected into the active layer 323. Is formed.

FIG. 3 is a diagram showing the paths of the light beams in the RMLA 806 for the light beams 211 and 212, respectively. Since the light beam 211 and the light beam 212 are incident on the mirror 205 along paths that are substantially parallel to each other but offset from each other, the light beams 211 and 212 also enter the RMLA 206 while being substantially parallel to each other, but offset from each other vertically. After being reflected by the roof type reflecting surface, they are emitted in a state where they are vertically shifted from each other. In this embodiment, the path of the first light beam passing through the upper part is reflected and deflected by the mirror 207 held on the upper part of the housing 201, so that the photoconductor 2
50 on which the first and second groups of light beams 21
Images 1 and 212 are formed at the same point. As a result, as described above, the exposure dots are formed on the photoconductor 250 as a result of the overlapping exposure of the light beams 211 and 212. In other words, in the optical line printhead 200 according to this embodiment, the light radiation formed in the active layer 323 of the LED 302 is efficiently used for exposure.

By the way, in the optical line print head 200 shown in FIG. 1 or 3, the optical path length of the light beam 211 deflected by the mirror 204 is slightly longer than the optical path length 212 of the light beam 212. I understand.
Therefore, the light beam 211 is applied onto the photoconductor 250 by RMLA2.
When the light beam 212 is focused by the action of the lens 206 a in 06, the light beam 212 is focused at a position slightly deviated from the surface of the photoconductor 250. In other words, the size of the exposure dot formed on the photoconductor 250 by the light beam 212 in this state is larger than the size when the beam 212 is correctly focused. Similarly, when the light beam 212 is focused on the photoconductor 250, the light beam 211 is diffused on the photoconductor 250 and the size of the exposure dot is enlarged. However, since these exposure dots are formed at a predetermined pitch especially in the main scanning line direction, the size in the main scanning line direction needs to be the same for the light beam 211 and the light beam 212.

FIGS. 4 and 5 show an embodiment having a structure for avoiding the problem that the exposure dots formed on the photoconductor 250 by the light beams 211 and 212 have different sizes in the main scanning line direction. . However, in FIGS. 4 and 5, the same components as those described above are designated by the same reference numerals and the description thereof will be omitted.

In the embodiment of FIG. 4, each LED 3
On the front end face 302a of No. 02, a mask member 302x that regulates the size of the light beam 211 emitted from the end face 302a in the main scanning line direction H is formed. As a result, the light beam 21
1 has a width smaller than the light beam 212 in the main scanning line direction, and even if the light beam 211 is diffused in the state where the beam 212 is focused on the photoconductor 250, The size or width of the formed exposure dot in the main scanning line direction is substantially the same as the width of the exposure dot formed by the beam 212.

FIG. 5 shows a modification of the embodiment shown in FIG.
Instead of forming the mask member 302x on the front end surface 302a of D302, the mask member 302y is formed on the upper main surface 302b. By forming the mask member 302y,
The size of the second light beam 212 emitted from the upper main surface 302b of the LED 302 is regulated in the main scanning line direction, and as a result, the exposure dot formed on the photoconductor 250 by the light beam 212 in the main scanning line direction. The size of the light beam 211
Are focused on the photoconductor 250 and the light beam 212
It is possible to match the corresponding size of the exposure dot formed by the light beam 211 even when the light is diffused on the photoconductor.

FIG. 6 shows the structure of an optical line print head according to another embodiment of the present invention. In the figure, the same reference numerals are assigned to the parts described in the previous embodiment, and the description thereof will be omitted.

In the embodiment of FIG. 6, a prism member 204x is used instead of the mirror 204. The prism member 204x is made of a transparent material having a high refractive index such as glass, and has an incident surface on which the light beam 211 from the LED 203 is incident, a reflection surface for reflecting / deflecting the incident light beam 211, and the reflection surface. It has an emission surface for emitting the light beam 211, and in the example shown in the figure, it has a configuration extending from the reflection surface to the emission surface. That is, the light beam 2
Reference numeral 11 reflects on the reflecting surface of the prism 211 and then propagates through the glass forming the prism member toward the exit surface. At this time, since the prism member 204 has a high refractive index, the effective optical path length of the light beam 211 is shortened, and the difference between the optical path length of the light beam 212 and the optical path length of the beam 211 is minimized.

FIG. 7 is a diagram showing the construction of an optical line print head according to another embodiment of the present invention. However, in the figure, the same reference numerals are given to the portions described in the previous embodiment, and the description thereof will be omitted.

Referring to FIG. 7, in this embodiment,
The mask member 20 is formed on the incident surface of the prism member 204x except for the portion where the light beam 211 is incident from the LED 203.
4y is formed, and the mask member 204y forms the light beam 211
It prevents the mixing of other light beams into the. As a result, the resolution on the photoconductor 250 is improved.

By the way, in each of the above embodiments, LE
The light beam 211 emitted from the end face of D302 is
The active layer 323 of the LED 302 has a flat shape corresponding to the cross-sectional shape (see FIG. 2) of the end surface 302a of the active layer 323, which is shrunk in the sub-scanning direction, while the upper main surface 302 of the LED 302.
The light beam 212 emitted from b has a rectangular shape corresponding to the planar shape of the LED 302. Therefore, in the present invention, when the light beams 211 and 212 are simultaneously imaged on the photoconductor 250 to form the exposure dots, the size or width of the exposure dots in the main scanning line direction is made uniform according to each of the embodiments. However, the difference in size in the sub-scanning line direction remains.

FIG. 8 is a diagram showing the construction of an optical line print head according to yet another embodiment of the present invention for correcting the difference in the size of the exposure dot in the sub-scanning line direction.
However, in the figure, the same reference numerals are given to the portions described in the previous embodiment, and the description thereof will be omitted. Figure 8
In the present embodiment, the prism member 20 is referred to.
Cylindrical surface 2 having a negative power with a 4x reflecting surface
04z and the cylindrical surface 204z
The light beam 211 emitted from the front end surface of the ED 803 is expanded on the photoconductor 250 in the sub-scanning line direction. As a result, in addition to the effect of shortening the effective optical path length of the light beam 211 in the prism member 204x, the shape of the exposure dot formed by the beam 211 forms the beam 212 in both the main scanning line direction and the sub-scanning line direction. It becomes possible to match the shape of the exposure dot.

FIG. 9 is a view showing the arrangement of an optical line print head according to another embodiment of the present invention. In FIG.
The same reference numerals are given to the portions described in the previous embodiment,
The description is omitted.

Referring to FIG. 9, a cylindrical lens having a negative power is arranged on the path of the light beam 211, and the size of the exposure dot by the beam 211 on the photoconductor 250 is enlarged in the sub-scanning line direction. . On the other hand, a cylindrical lens having a positive power is arranged on the path of the light beam 212, and the beam 21 on the photoconductor 250 is
The size of the exposure dot by 2 is compressed in the sub-scanning line direction. As a result, the first light beam 211 and the second light beam 212 form exposure dots having substantially the same size and shape on the photoconductor 250. In the embodiment of FIG. 9, the lenses 211a and 211b do not necessarily have to be provided at the same time, and the desired effect can be obtained by providing only one of them.

FIG. 10 is a view showing the arrangement of an optical line print head according to another embodiment of the present invention. Figure 10
Among the parts described in the previous embodiment, the same reference numerals are given and the description thereof is omitted.

Referring to FIG. 10, in this embodiment, the LED
A ceramic substrate 202 carrying 203 is formed on the housing 201 with an inclination with respect to the center line of the RMLA 806. With this configuration, the incident angle of the light beam 212 emitted from the upper main surface of the LED 203 on the mirror 205 becomes steep, and the light beam 212 reflected by the mirror 205 is reflected.
Can be set so as to pass through the center of the lens 206a.
As a result, distortion due to the aberration of the light beam 212 can be minimized. In particular, the path of the light beam 212 emitted from the upper main surface of the LED 203 through the substrate 202 is RMLA20.
It is preferable to set so as to be orthogonal to the path of the light beam 212 which is reflected by 6 and is emitted toward the photoconductor 250.

FIG. 11 is a view showing the arrangement of an optical line print head according to another embodiment of the present invention. Figure 11
Among the parts described in the previous embodiment, the same reference numerals are given and the description thereof is omitted.

Referring to FIG. 11, in this embodiment, the prism member 204x is provided on the housing 201 as shown by the arrow.
It is movably held in the sub-scanning line direction, that is, in a direction substantially perpendicular to the substrate 202, and as a result, the prism member 2 is held.
The 04x reflecting surface can also be moved in the sub-scanning line direction. As a result of such a configuration, it becomes possible to move the position of the exposure dot by the first group of light beams 211 in the sub-scanning line direction on the photoconductor 250, and the light beam 211 exposes the exposure dots and the light beam 212. Dots and
Accurate matching can be achieved on the photoconductor 250.

FIG. 12 is a view showing the arrangement of an optical line print head according to another embodiment of the present invention. 12
Among the parts described in the previous embodiment, the same reference numerals are given and the description thereof is omitted.

In the structure of this embodiment, as shown by the arrow in FIG. 12, the upper part of the casing 201, which corresponds to the exit of the light beam facing the photoconductor 250, is located above the first scanning line. A shutter member 212b that is movably held between the first position and the second lower position is provided. Shutter member 2
12b blocks the light beam 212 when in the first position. In other words, by setting the shutter member 212b to the first position, the LED on the photoconductor 250 is
Exposure is performed only by the light beam 211 emitted from the end face of 203 and flat in the sub-scanning line direction. By using such a flat light beam 211, it is possible to perform high-density exposure with improved resolution in the sub-scanning line direction. On the other hand, by setting the shutter member 212b to the second position, the exposure dots are formed on the photoconductor 250 by the first light beam 211 and the second light beam 212 in an overlapping manner. The light beam 212 is emitted from the upper main surface of the LED 203 and has a rectangular shape.
On the 50, corresponding rectangular exposure dots having a larger size in the sub-scanning line direction are formed. as a result,
The optical line print head according to the present embodiment can perform low resolution exposure by setting the shutter member 212b to the second position. That is, in the optical line print head according to the present embodiment, the shutter member 21
By controlling 2, it is possible to change the resolution of the recorded image.

FIG. 13 shows a modification of the embodiment shown in FIG.
A cylindrical lens 212c that moves together with the shutter member 212b is provided. In the illustrated example, the cylindrical lens 212c has negative power, and
The size of the exposure dot formed by the light beam 211 with respect to the exposure dot formed above by the light beam 212 in the sub-scanning line direction is adjusted. In addition, the shutter member 21
2b corresponding to the lens 212 on the housing 201.
A concave portion 212d for accommodating c is formed, and the lens 212c
Is housed in the recess 212d when the shutter member 212b is in the first position. Also, the lens 212c
On the shutter member 212b.
Are held so that they are inserted in the optical path of the light beam 211 when in the second position.

The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the present invention.

[0080]

According to the present invention, the light beam formed by the light emitting diode is used to expose an image on the photoconductor by using two different light beams emitted from the end surface and the upper main surface of the light emitting diode. Can be used efficiently.
Also, by selectively using the two light beams,
The resolution of the image formed on the photoconductor can be changed as necessary. Further, by using RMLA in the optical system, it is possible to minimize the optical loss in the optical system without requiring excessive processing accuracy.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of an optical line printhead according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a structure of a light emitting diode chip used in the optical line printhead of FIG.

3 is a diagram showing the path of a light beam in the optical line printhead of FIG.

FIG. 4 is a view showing another structure of a light emitting diode used in the optical line print head of FIG.

5 is a view showing still another structure of a light emitting diode used in the optical line print head of FIG.

FIG. 6 is a cross-sectional view showing the structure of an optical line printhead according to another embodiment of the present invention.

FIG. 7 is a sectional view showing a configuration of an optical line print head according to another embodiment of the present invention.

FIG. 8 is a cross-sectional view showing the structure of an optical line print head according to another embodiment of the present invention.

FIG. 9 is a cross-sectional view showing the structure of an optical line print head according to another embodiment of the present invention.

FIG. 10 is a sectional view showing a configuration of an optical line print head according to another embodiment of the present invention.

FIG. 11 is a cross-sectional view showing the structure of an optical line print head according to another embodiment of the present invention.

FIG. 12 is a sectional view showing a configuration of an optical line print head according to another embodiment of the present invention.

FIG. 13 is a cross-sectional view showing the structure of an optical line print head according to another embodiment of the present invention.

FIG. 14 is a perspective view showing a configuration of a conventional optical line printhead.

15 is an enlarged view showing an LED used in the optical line printhead of FIG.

16 is a diagram showing an optical system used in the optical line printhead of FIG.

FIG. 17: Known roof mirror lens array (RML
It is a figure which shows the structure of A).

[Explanation of symbols]

101 base plate 102 heatsink 103 wiring board 104 LED chip 104 ₁ ~104 ₃ LED 104a end surface 104b upper electrode 105 driving integrated circuits 105a bonding pads 106 bonding wires 107 Cable 108 loaded lens array 109 adjust member 110 roof mirror lens array 111 lens array 112 Roof mirror array 113 Mirror 150 Photoconductor 200 Optical line print head 201 Housing 202 Ceramic substrate 203 LED chip 204 Mirror 204a Adjustment mechanism 204x Prism member 204y Mask member 204z Cylindrical surface 205 Mirror 206 Roof mirror lens array 206a Lens array 206b Aperture hole 206c Roof mirror array 206d Support member 207 Mira 207a Adjustment mechanism 211 First group light beam 211a Cylindrical lens 212 Second group light beam 212a, 212b Cylindrical lens 212b Shutter member 212d Recess 250 Photoconductor 301 Substrate 301c Layered structure 302 LED 302a LED front end surface 302b LED upper principal surface 302x, 302y Mask member 303 Bonding pad 308 Wiring pattern 311 Separation groove 321 Buffer layer 322,324 Cladding layer 323 Active layer 325 Carrier diffusion layer 326 Contact layer 327 Upper electrode 328 Lower electrode

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H04N 1/036 A

Claims (17)

[Claims] 1. A light emitting diode array comprising a plurality of light emitting diodes arranged in at least one row, and optical means for converging each of the light beams formed by the plurality of light emitting diodes onto a photoconductor. In a light source device for an optical printer, which forms an image as a set of exposure dots on a photoconductor by selectively driving the light emitting diodes, each of the plurality of light emitting diodes is defined by an upper main surface and an end surface. The first light beam is emitted from the end surface along the first optical path, and at the same time, the second light beam is emitted from the upper main surface along a second optical path different from the first optical path; Includes: a plurality of lenses that are repeatedly arranged at a predetermined pitch in the arrangement direction of the light emitting diodes, and the first and the first light emitted from each of the plurality of light emitting diodes. A lens array for converging each of the second light beams on the photoconductor; a roof type repeatedly formed in the array direction of the light emitting diodes at a pitch corresponding to a predetermined pitch of the plurality of lenses in the lens array A roof mirror array having a reflecting surface and sequentially reflecting an incident light beam on a pair of adjacent roof-type reflecting surfaces; a plurality of roof mirror arrays repeatedly formed at a pitch corresponding to the predetermined pitch in the array direction of the light emitting diodes Has a light beam passage of
Diaphragm plate means for blocking stray light between adjacent lenses; said lens array is directed to said roof mirror array such that said first and second light beams formed by said light emitting diodes pass through said lens array. Roof mirror arranged so as to be incident on the roof mirror array and to pass through the lens array along each optical path after being reflected by the roof mirror array and to be converged on the photoconductor. A lens array; and an optical path of the first and second light beams, wherein the first and second light beams form exposure dots at substantially the same position for each light emitting diode on the photoconductor. A light source device for an optical printer, comprising: an optical path setting means for setting to form. 2. Each of the light emitting diodes is formed with a light shielding part on the end face so as to restrict the size of the first light beam with respect to the arrangement direction of the light emitting diodes. The light source device for an optical printer according to claim 1. 3. Each of the light emitting diodes has a light blocking portion formed on the upper main surface so as to restrict the size of the second light beam with respect to the arrangement direction of the light emitting diodes. The light source device for an optical printer according to claim 1, wherein the light source device is an optical printer. 4. The first optical path setting means receives the first light beam emitted from the end face of the light emitting diode, reflects the first light beam, and causes the first light beam to enter the roof mirror lens array. The second light beam emitted from the upper main surface of the light emitting diode is incident,
A second reflecting unit that reflects the light and makes it incident on the roof mirror lens array and an optical path of the first and second light beams are relatively deflected, and the first light beam and the second light beam are reflected. 2. The light according to claim 1, wherein the beam comprises a third reflecting means for adjusting each light emitting diode on the photoconductor to form an exposure dot at substantially the same position. Light source device for printers. 5. The first reflecting means receives a first light beam from an end surface of the light emitting diode and reflects the first light beam, and the first mirror reflected by the first mirror. A second mirror that receives a light beam and reflects it toward the roof mirror lens array;
The second reflecting means comprises the second mirror, and in the second reflecting means, the second mirror directly receives the second light beam from the upper main surface of the light emitting diode. The light source device for an optical printer according to claim 4, wherein the light is reflected and emitted toward the roof mirror lens array along an optical path different from the optical path of the first light beam. 6. The third reflecting means is provided in an optical path of the first light beam and deflects the optical path by reflecting the first light beam emitted from the roof mirror lens array. 5. The light source device for an optical printer according to claim 4, wherein the light source device comprises a mirror. 7. The first mirror has an incident surface on which the first light beam emitted from the end surface of the light-emitting diode is faced, which is opposed to the end surface, and the first light incident on the incident surface. The light source device for an optical printer according to claim 5, comprising a prism member having a reflecting surface for reflecting the beam and an emitting surface for emitting the first light beam reflected by the reflecting surface. 8. The optical printer according to claim 7, wherein the prism member has a light blocking member formed on the incident surface except for a portion where the first light beam is incident from the light emitting diode. Light source device. 9. The reflecting surface of the prism member is formed so that the size of the first light beam on the photoconductor increases in a direction orthogonal to the arrangement direction of the light emitting diodes. The light source device for an optical printer according to claim 7, wherein the light source device comprises a cylindrical surface having negative power. 10. The prism member is arranged such that a position of the first light beam on the photoconductor can be displaced in a direction orthogonal to an arrangement direction of the light emitting diodes with respect to the second light beam. , And is held so as to be movable in the direction of the emission surface.
The light source device for an optical printer according to any one of the above. 11. The optical path setting means is disposed in the optical path of the first light beam, and the size of the first light beam on the photoconductor is orthogonal to the arrangement direction of the light emitting diodes. 11. The light source device for an optical printer according to claim 1, further comprising a cylindrical lens having a negative power, the cylindrical lens having a negative power. 12. The optical path setting means is arranged in the optical path of the second light beam, and the size of the second light beam on the photoconductor is orthogonal to the arrangement direction of the light emitting diodes. The light source device for an optical printer according to any one of claims 1 to 11, further comprising a cylindrical lens having a positive power and formed so as to decrease in a direction to move. 13. Each of the light emitting diodes has a virtual vertical line drawn with respect to the upper main surface with respect to a chief ray of the second light beam from the roof mirror lens array to the photoconductor. 2. The light source device for an optical printer according to claim 1, wherein the light source device is provided so as to be substantially orthogonal to each other. 14. The light emitting diode according to claim 1, wherein each of the light emitting diodes has an electrode having a limited area on the upper main surface so that the second light beam can pass therethrough. A light source device for an optical printer according to claim 1. 15. A shutter means is provided on an optical path of the first and second light beams and controls irradiation of the photosensitive member with the first and second light beams. The light source device for an optical printer according to claim 1, wherein the light source device is an optical printer. 16. The shutter means causes the first and second light beams to simultaneously reach the photoconductor at a first position, and selectively blocks only the second light beam at a second position. 16. The light source device for an optical printer according to claim 15, wherein: 17. The shutter means includes a cylindrical lens having a negative power so that the cylindrical lens is inserted in an optical path of the first light beam when the shutter means is at the first position. The light source device for an optical printer according to claim 16, which holds the light source device.