JP4574006B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus based on an electrophotographic process such as a copying machine, a printer, and a facsimile, and more particularly to a back exposure type image forming apparatus in which an exposure unit is provided in a photosensitive body.
[0002]
[Prior art]
In recent years, development of downsizing, high speed, and low power consumption has become important in image forming apparatuses such as printers using laser beams as exposure means. Conventionally, a method of scanning a laser beam using a polygon mirror and forming an image on the outer periphery of a photosensitive drum has been mainly developed and put into practical use. When the speed is increased by this method, since the rotation speed of the polygon mirror is limited, as disclosed in Japanese Patent Laid-Open No. 5-294005, scanning that can be recorded in one scan by forming the light source into a plurality of arrays. An example of increasing the number of lines is known.
[0003]
Another example is that, due to the limitations of the scan system, batch exposure is performed over the width in the main scanning direction of the recording medium with a high-density surface emitting laser, and the speed is increased only by sub-scanning by rotating the photosensitive drum. No. 64-42667 and Japanese Patent Laid-Open No. 9-200431. FIG. 9 shows a typical drawing disclosed in Japanese Patent Laid-Open No. 9-200431. The light beam emitted from the two-dimensional arrayed surface emitting laser 110 is magnified by the lens 181, reflected while being condensed by the concave mirror 182, and irradiated onto the photosensitive drum 115 to form a light latent image. In this case, as shown in FIG. 10, the light emitting points 170 of the surface emitting laser 110 are arranged obliquely so that a resolution as indicated by 150, which is smaller than the interval between the light emitting points of the surface emitting laser, is obtained. It is.
[0004]
On the other hand, in a method using such a lens system, a certain space is required, so there is a limit to downsizing. In particular, in the colorization of a laser printer, since a plurality of optical systems are required, downsizing becomes even more difficult.
[0005]
One method for solving the problems related to speeding up and downsizing is to form a photosensitive drum by laminating a transparent electrode such as ITO (indium tin oxide) and a photoconductor layer on a cylindrical transparent support. In addition, a method called “back exposure” in which an array of exposure means is built in a photosensitive drum and a latent image is formed by light from the inner wall of the drum has been proposed (Japanese Patent Laid-Open No. 58-153957, Image Electronics Society of Japan). 16 (5) 1987, pages 306-312). FIG. 11 shows a typical example of an image forming apparatus (Japanese Patent Laid-Open No. 5-94068) using an LED array in this manner.
[0006]
An exposure head 202 is built in the photosensitive drum 201. The exposure head 202 includes a printed circuit board 220 and an LED array 221. An image is formed on the photosensitive drum 201 by a Selfoc lens 223.
[0007]
The developing unit 203 supplies toner to the latent image formed on the photosensitive drum 201 by the exposure head 202 to form a toner image. The toner image is transferred to the recording medium P by the transfer roller 204, and is fixed on the recording medium P as a permanent image by the fixing device 207.
[0008]
In such a configuration, since the optical system is housed in a hollow photosensitive drum, it can be made very small, and since LEDs are arrayed, the speed is not limited by the rotational speed of the polygon mirror. Can be realized.
[0009]
[Problems to be solved by the invention]
By the way, the surface emitting laser oscillates at a low threshold, can be easily formed into a two-dimensional array, and is a light source suitable for the printer as described above, but lacks stability in the transverse mode and the polarization mode. There is a point.
[0010]
For this reason, when an image is formed by a lens system or reflected by a mirror, the reflectivity varies depending on the mode, so that the mode instability becomes uneven exposure and leads to deterioration of image quality. In order to stabilize the mode, it is necessary to reduce the area of the light emitting point to achieve a single mode. As a result, the laser power that can be output stably becomes as low as about 1 mW, and thus the loss of light in the optical system must be minimized.
[0011]
In order to avoid such a problem, it is conceivable to provide an exposure head near the surface of the photosensitive drum for contact exposure. However, if the exposure head is arranged near the surface of the photosensitive drum, a problem of contamination with toner occurs.
[0012]
On the other hand, the method of arranging the LED array in the photosensitive drum has a problem that the power consumption of the LED is large, so that a large-capacity power source is required, and the entire apparatus is enlarged. In addition, since the overall heat generation amount increases and the light intensity etc. fluctuates, uneven exposure occurs. Further, since the LED has a large emission angle of light emission, a relatively large lens is necessary, and the power utilization efficiency is further increased due to low light use efficiency.
[0013]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an image forming apparatus with low power consumption, compactness, excellent portability, and capable of high-speed recording.
[0014]
[Means for Solving the Problems]
  The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention has a photoreceptor in which a transparent conductor layer and a photoconductor layer are sequentially provided on a transparent support, and a light irradiation means that is provided inside the photoreceptor and irradiates light.
Image formation in which the light irradiation means irradiates light from the transparent support side to expose the photoconductor layer, and supplies a toner to the exposed portion on the photoconductor layer to form a visible image In the device
  The light irradiation means includes a substrate and a surface emitting laser provided on the substrate and emitting light in a vertical direction.And
  The substrate has flexibility, and the surface emitting laser is attached so as to be in close contact with the inner wall of the photoconductor, and all of the epitaxial growth semiconductor substrate used to form the surface emitting laser is removed. Has beenAn image forming apparatus characterized by the above.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
The image forming apparatus according to the present invention will be described below in more detail with reference to the drawings.
[0029]
Example 1
A first embodiment of the present invention will be described with reference to FIGS.
[0030]
FIG. 1 shows a back exposure type image forming apparatus using a surface emitting laser array according to this embodiment, for example, a laser beam printer.
[0031]
As shown in FIG. 1, the image forming apparatus of the present embodiment has a photosensitive drum (photosensitive body) 1 as an image carrier, and an exposure apparatus 2 having a surface emitting laser array is installed therein. The surface potential of the photosensitive drum 1 is changed by light from the exposure device 2, and the toner 5 is supplied from the toner container 4 through the developing device 3 according to the potential. The developed toner 5, that is, the toner image (visible image) is conveyed to the transfer portion by the rotation of the photosensitive drum 1, and the toner image is transferred onto the recording material 10 by the action of the transfer roller 8 connected to the bias power source 7. The Further, the recording material 10 is conveyed to a fixing device 9 composed of a fixing roller, where the toner image is fixed on the recording material 10.
[0032]
As shown in FIG. 2, the photosensitive drum 1 protects the transparent conductive layer 21 serving as an electrode on the surface of the transparent support 20, the photoconductive layer 22 that is exposed to light from the exposure apparatus 2, and the photoconductive layer 2. A surface layer 23 is sequentially formed.
[0033]
The developing device 3 includes a magnetic roller 3a and a nonmagnetic conductive sleeve 3b, and the conductive toner 5 supplied from the toner container 4 adheres to the exposed portion of the surface of the photosensitive drum 1. At this time, a developing bias is applied between the developing device 3 and the photosensitive drum 1 from the bias power source 6. Electric charges are injected into the unexposed area by the contact of the conductive toner 5, and the photoconductive layer 22 and the toner layer on the photosensitive drum 1 have substantially the same potential, so that the toner does not adhere. On the other hand, the potential is lowered and the toner adheres to the portion subjected to the light exposure, and the potential rises again after the toner transfer, and the unnecessary toner 5 is removed by the magnetic force of the magnetic roller 3a. That is, the developing device 3 also has a cleaning function.
[0034]
As the toner, a toner whose surface is covered with a conductor such as SiC or carbon and which includes magnetic particles such as ferrite or magnetite at the center is used. The materials are not limited to those exemplified above.
[0035]
As described above, the image forming apparatus of the present embodiment performs charging, exposure, development and cleaning almost simultaneously. Therefore, the image forming process and the configuration of the apparatus are greatly simplified as compared with the conventional type using corona discharge, and the voltage can be reduced and the generation of ozone can be reduced. Furthermore, since a surface emitting laser is used as the exposure apparatus in the present invention, a significant reduction in power consumption is possible. Accordingly, it is possible to provide an optimum laser beam printer as a portable device as well as space saving by simultaneously reducing the size and power consumption of the apparatus.
[0036]
Note that the arrangement, size, and vertical relationship of each component in FIG. 1 are exemplarily shown, and are not limited to this configuration.
[0037]
Next, each component of the image forming apparatus in the present embodiment will be further described.
[0038]
The transparent support 20 of the photosensitive drum 1 is preferably made of a translucent resin such as polyimide, epoxy, polyester, or polycarbonate, but may be an inorganic material such as glass or quartz. The transparent support 20 constitutes a cylindrical body having a diameter of 2.5 cm and a length of 22 cm (A4 compatible). In the state of a cylindrical body, a transparent conductive layer 21, a photoconductive layer 22, and a surface layer 23 are sequentially formed on the surface.
[0039]
The transparent conductive layer 21 is preferably formed by vapor deposition or coating method of ITO (indium tin oxide). Alternatively, SnO, ZnO, Au, Al thin film or the like may be used.
[0040]
The photoconductive layer 22 is preferably formed by depositing a-Si or a-SiC on the surface of the cylindrical body by plasma enhanced chemical vapor deposition (PECVD) or the like. The film formation may be a sputtering method, a vapor deposition method, or the like. If necessary, a multilayer structure in which conductivity is changed by doping control, hydrogen content control, or the like, or Ge, N, or the like may be mixed for band gap control.
[0041]
The surface layer 23 is made of an insulating resin such as polyimide or polyethylene, or an inorganic material such as SiN, SiON, or SiC in order to protect the surface, charge, and withstand voltage.
[0042]
Next, an exposure apparatus 2 comprising a surface emitting laser array will be described with reference to FIG.
[0043]
As shown in FIG. 3A, the exposure apparatus 2 includes a support having a wiring pattern formed on a substrate 31 such as a glass epoxy substrate or a Si substrate, and the surface emitting laser array 30 is provided on the support. And a CMOS driver 32 is mounted. A flat microlens array 33 is bonded to the surface of the surface emitting laser array 30 as shown in FIG. The size of the substrate 31 in the longitudinal direction is substantially the same as the size of the photosensitive drum 1 in the longitudinal direction.
[0044]
In the surface emitting laser array 30, the surface emitting lasers 35 are arranged in two staggered rows, and the pitch of the light emitting points 34 in the surface emitting lasers 35 in each row is set to 84.6 μm. The light emitting points 34 in the second row are arranged so as to interpolate in the center between the light emitting points 34 in the first row, and therefore the light emitting points 34 are arranged at a pitch of 42.3 μm, so that it corresponds to 600 dpi. can do. The row interval, that is, the interval between the light emitting points 34 in the first row and the second row is also set to 84.6 μm, and drive control is performed so that the exposure points are arranged in one row on the photosensitive drum by dynamic lighting control. .
[0045]
Further, the surface emitting laser array 30 has 2 rows × 50 elements (= 100 elements, that is, 100 surface emitting lasers) as one chip, and 47 chips are mounted on the substrate 31 in a straight line, for a total of 2 rows. × 50 × 47 = 4700 elements are integrated, and the width of the photosensitive drum 1, that is, the size in the longitudinal direction, about 19.8 cm can be collectively exposed. That is, the light emitting point 34 of the surface emitting laser covers substantially the entire longitudinal direction of the photosensitive drum 1. However, a part of the arrayed surface emitting laser may be used not for image recording but for control signals. In addition, as described later, dynamic lighting in which lighting is performed sequentially with a time difference is common to exposure instead of simultaneous lighting (static lighting).
[0046]
The chip is mounted on the substrate 31 by using a flip chip bonder device in which the chip outer shape and the electrode pattern on the substrate 31 are aligned and sequentially mounted, and bonding is performed by Au-Au pressure bonding, Au-Sn or Pb. -Sn eutectic, batch reflow with cream solder or Ag paste. Note that the number of elements, the resolution, and the width for batch exposure are shown as examples and are not limited to the above numbers. In addition to the flat microlens formed of glass, a low-cost resin mold lens array or the like may be used for the lens.
[0047]
On the other hand, the surface-emitting laser 35 was driven by using a chip in which a bare chip of a CMOS driver IC 32 was flip-chip bonded on the same substrate 31 using a solder ball or Ag paste. A plurality of CMOS driver ICs 32 are mounted side by side in the same manner as the surface emitting laser 35 as shown in FIG.
[0048]
  The wirings 37 and 38 on the substrate 31 are made of Cu—Ni—Au, Cu—Ni—Al, Ti—Pt—Au, but are not limited thereto. The surface of the p-electrode 35 on the laser element is Au, and a wire as a connection with the Si-IC is used.YaThe bonding 36 is made of Au or Al—Si. The wiring 38 leads out a cathode electrode that is a common electrode of the surface emitting laser array 30 and is wired from a plurality of locations in order to reduce the resistance. Further, although the signal wiring 37 is not shown in the drawing, a pattern is printed so that wiring can be performed on both ends of the substrate 31.
[0049]
The recording signal is exchanged with the apparatus main body by wiring through connectors (not shown) fixed to both ends of the substrate 31. As the CMOS driver, a current source constituted by a current mirror may be used, but voltage source driving in which CMOS logic is directly injected into a surface emitting laser is advantageous for cost reduction.
[0050]
The surface emitting laser of the present embodiment outputs 1 mW at a threshold of about 2 mA and 5 mA in the 780 nm band, and the voltage at the time of 5 mA driving in normal operation is 2.5V. In the case of 3.3V-CMOS level, the injection current is controlled by inserting a series resistor, and the array chip resistor is mounted on the substrate 31 in advance. The wavelength band of the surface emitting laser is not limited to the above.
[0051]
By the way, even though the injection current per element is small, if a current is applied to 2350 elements in a row at once, the current becomes large and heat generation increases, so that the surface emitting laser can be driven at high speed and the optical power density is high. Taking advantage of the high level, if the lighting time of each element is set to about 10 nsec, the time required to write one line by dynamic lighting is 10 nsec × 4700 = 47 μsec. The time required is 47 μsec × 7100 = 0.33 sec. Actually, there is a control delay time and the like, but 1 sheet / second or less can be easily achieved.
[0052]
Although the above numerical values are exemplarily shown, the exposure time per pixel is determined by the relationship between the developing device and the optical power, and the exposure apparatus can perform dynamic lighting at a higher speed. Conversely, dynamic lighting may be performed by reducing the light power to increase the exposure time and increasing the number of simultaneous lighting. By using dynamic lighting for every n elements instead of dynamic lighting for each element, the speed can be increased by a factor of n. In the surface emitting laser, since the driving current is small, simultaneous lighting of about 10 elements is easy, and the speed 10 times that of the above numerical example can be easily achieved.
[0053]
As described above, the image forming apparatus of the back exposure type of the present invention uses the surface emitting laser array, so that the degree of freedom of design is widened and dramatic high-speed recording can be achieved.
[0054]
In addition, as described above, the surface emitting laser has a low threshold current and can output light of 1 mW at an operating current of about 5 to 10 mA. Therefore, the operating current is 1/10 or less compared with a back exposure apparatus using an LED array, and the power consumption can be greatly reduced.
[0055]
Furthermore, when the single mode is selected, the light emission angle is as small as several degrees and the emission pattern is circular, so that the lens design can be made easy and small, and the light utilization efficiency can be improved.
[0056]
In addition, since contact exposure is performed from the inner wall of the photosensitive drum, there is no problem of contamination with toner, and no optical system is required, so the drum diameter is small, and thus the entire apparatus can be greatly reduced in size.
[0057]
Such a small and low power consumption laser printer can be suitably used particularly as a portable printer.
[0058]
Further, since the polygon mirror is not used, the printing speed is not limited by the number of rotations, and the number of light emitting point arrays is covered by the entire width of the recording paper, thereby providing an ultra-high speed printer. .
[0059]
In this embodiment, the back exposure using the corona discharge is described. However, the back exposure may be performed using the corona discharge as in the prior art. In this embodiment, a cylindrical photosensitive drum is shown, but a flat belt-like photosensitive member may be used.
[0060]
Example 2
Next, a second embodiment of the present invention will be described with reference to FIGS.
[0061]
In this embodiment, the exposure apparatus is composed of a flexible substrate and is brought into close contact with the inner wall of the photosensitive drum, thereby improving the focal position accuracy of the condensing lens. In the first embodiment, since a rigid mounting substrate is used, it is arranged away from the inner wall of the photosensitive drum, and a flat microlens array is used to focus on the photoconductive layer. However, high installation position accuracy is required. It was. On the other hand, by bringing the exposure device into close contact with the inner wall of the photosensitive drum, the distance from the exposure device to the photoconductive layer of the photosensitive member is about 2 mm (determined by the thickness of the transparent support of the photosensitive drum), and a surface emitting laser. Since the radiation angle of the lens is about several degrees, the curvature of the lens used is small and the focal position accuracy can be improved.
[0062]
FIG. 4 shows a state in which the flexible exposure apparatus 60 of this embodiment is in close contact with the inner wall of the photosensitive drum 1. A configuration for realizing such a flexible exposure apparatus 60 is shown in FIG.
[0063]
As shown in FIG. 5, the flexible exposure apparatus 60 includes a flexible printed board (commonly called FPC) 50 having a flexibility such as polyimide or polycarbonate on which a wiring pattern is printed. As the driver 32, Si-IC 32 is flip-chip mounted with Ag paste 56 or the like as in the first embodiment, and the back surface of the Si-IC 32, which is a bare chip, is polished to about 100 μm.
[0064]
On the other hand, surface emitting lasers are thinned by epitaxial lift-off to provide surface wiring in order to eliminate wire bonding for contact exposure. An insulating film 53 is formed on the surface of the thinned surface emitting laser for wiring, and holes are formed for the light exit window 54 and electrode wiring. The surface cathode electrode 52 and the Si-IC 32 are connected by a wiring 55 produced by vapor deposition and lift-off. Further, although not shown on the surface, the surface of the light emitting point 54 is covered with a resin mold in which microlenses are formed to protect the surface.
[0065]
A method for manufacturing a surface emitting laser having a thin film structure will be described with reference to FIGS. In FIG. 6A, an n-DBR mirror 41 made of an AlGaAs multilayer film with an Al composition ratio changed on an n-GaAs substrate 40 which is a thinning substrate, and a quantum consisting of three layers of GaAs / AlGaAs. A one-wavelength resonator 42 composed of a well active layer and an AlGaAs spacer layer, a DBR mirror 43 composed of a p-type AlGaAs multilayer film in which the Al composition ratio is changed, and a p-GaAs contact layer (not shown) on the outermost surface. Epitaxial growth was performed by a phase growth method or the like.
[0066]
The light emitting region is formed by performing cylindrical dry etching with a diameter of 20 μm and then heating while flowing water vapor to selectively oxidize only the vicinity of the active layer to form an AlxOy layer (selective oxide layer) 46. This is done by reducing the diameter to 5 μm. By this selective oxidation, it is possible to reduce the threshold value and to achieve a single mode. The etched recess is flattened by filling an optical resin 48 such as polyimide. Further, after forming separation grooves between the elements, they are flattened with a resin 49. SiNx was formed as an insulating film 44 on the surface other than the current injection region 47 so that only the current injection region 47 could be contacted. Finally, an anode electrode 45 made of Ti / Pt / Au is formed on the entire surface.
[0067]
In FIG. 6B, the surface emitting laser array manufactured as shown in FIG. 6A is polished to a thickness of about 100 μm, and then cut into chips by cutting with 2 × 50 elements, for example. Thereafter, this chip is bonded to the anode electrode pad 51 formed on the surface of the flexible substrate 50 by Au-Au pressure bonding or soldering.
[0068]
Next, in FIG. 6C, the n-GaAs substrate 40 is replaced with H.₂O₂+ NH_ThreeEtching is performed with a mixed solution of the above, and the etching is stopped with AlGaAs constituting the n-DBR mirror 41. Thereafter, AlGaAs is removed to expose an n-GaAs contact layer (not shown), and the cathode electrode 52 is formed. Although the shape of the cathode electrode 52 is arbitrary, in this embodiment, as shown in FIG. 5 (a), a doughnut-shaped light emitting window 54 having a diameter of 5 μm is used, and a high-order transverse mode of a surface emitting laser is obtained. It functions as a spatial filter that does not emit light.
[0069]
In this embodiment, since the surface emitting laser is an anode common type, it can be adapted to a high-speed driver IC, and further high-speed printing is possible.
[0070]
Furthermore, according to the present embodiment, the same effects as those of the first embodiment can be obtained, and as described above, the exposure apparatus can be installed in close contact with the inner wall of the photosensitive drum, so that the focal position accuracy can be improved.
Example 3
Next, a third embodiment of the present invention will be described with reference to FIG.
[0071]
In this embodiment, as shown in FIG. 3, the surface emitting lasers are not arrayed in a line, but the exposure apparatus is reciprocated inside the photosensitive drum to reduce the cost of the exposure apparatus.
[0072]
In the above-described embodiment, although high-speed printing is possible, in order to integrate several thousand or more surface emitting lasers, there is a concern about an increase in manufacturing cost due to a problem of yield and a problem of variation in emission intensity.
[0073]
Therefore, in this embodiment, the number of arrays is reduced by slightly reducing the high speed, and a low-cost image forming apparatus is realized.
[0074]
In FIG. 7A, a belt 73 is disposed so as to penetrate the photosensitive drum 1 in the longitudinal direction. The belt 73 is wound around the rollers 74a and 74b, and a reverse motor (not shown), for example, is connected to one of the rollers 74a or 74b as a drive source so that the belt 73 can reciprocate. Then, the exposure apparatus 2 is fixed to the surface of the belt 73 and reciprocating along the longitudinal direction of the photosensitive drum 1 is performed together with the belt 73.
[0075]
As shown in FIG. 7B, the exposure apparatus 2 has a configuration in which a 10 × 10 surface emitting laser array 72 and a Si-IC 71 for driving the 10 × 10 array are mounted on a mounting substrate 70. The surface emitting laser array 72 is mounted so as to be inclined by an angle α with respect to the moving direction X, and the leftmost element e1 in the upper column and the rightmost element e2 in the lower column in the figure are in the vertical direction. It is set to be the same interval as the pitch. As a result, exposure can be performed at an interval narrower than the interval between the emission points of the surface emitting laser.
[0076]
For example, when it corresponds to 1200 dpi, the pitch of the light emitting points is about 21.2 μm, but the element interval of the 10 × 10 array is formed in a square with a pitch of 212 μm, and α = an inclination angle of about 5.7 degrees. You can do it. In this case, printing of 100 lines, that is, a width of 2.12 mm is possible by scanning once in the width direction. By performing printing by reciprocating movement, it is possible to save the return scanning time. For example, to print about 30 cm in the vertical direction of A4, the number of scanning is about 140 times. When 0.1 sec is set for one scan, the printing speed is slowed down to 14 seconds / sheet, but it can be sufficiently applied to an apparatus that places importance on low cost and portability. If the resolution is lowered, the printing speed is naturally increased.
[0077]
Example 4
Next, a fourth embodiment of the present invention will be described with reference to FIG.
[0078]
In the above embodiment, the case of an image forming apparatus having a single color, that is, a single back exposure photosensitive drum has been described. In this embodiment, the present invention is a full color image forming apparatus having a four color image forming station. For example, it is applied to a full-color printer. That is, as shown in FIG. 8, the image forming apparatus of this embodiment has basically the same configuration as that of the back exposure type image forming apparatus using the surface emitting laser array described in the first embodiment. Further, yellow image forming station 80, magenta image forming station 81, cyan image forming station 82, and black image forming station 83 as image forming means are arranged in parallel along the moving direction of transfer material 10. is there. The same members as those described above are denoted by the same reference numerals, description thereof is omitted, and the drawings are simplified.
[0079]
By providing a configuration in which the above-described four back exposure photosensitive drums are arranged in parallel as in the present embodiment, it can function as a small full-color image forming apparatus. In particular, when four image forming stations are operated at the same time, when a surface emitting laser is used as in the present invention, the power consumption can be reduced. Therefore, compared with a full color image forming apparatus equipped with a conventional exposure apparatus. It is advantageous. Further, in this case, since the exposure means is small, the apparatus does not increase in size even when four photosensitive drums are arranged, and a portable color printer can be provided.
[0080]
【The invention's effect】
  As described above, the image forming apparatus of the present invention includes a photoconductor in which a transparent conductor layer and a photoconductor layer are provided in order on a transparent support, and light irradiation that is provided inside the photoconductor and emits light. And the light irradiation means irradiates light from the transparent support side to expose the photoconductor layer, and the exposed portion on the photoconductor layer is exposed to the photoconductor layer side. In an image forming apparatus that forms a visible image by supplying toner and selectively attaching the toner, the light irradiation unit includes a substrate and a surface emitting laser that is provided on the substrate and emits light in a vertical direction. YesThe substrate has flexibility, and the surface-emitting laser is attached so as to be in close contact with the inner wall of the photosensitive member. An epitaxial growth semiconductor substrate used to form the surface-emitting laser is provided. All removedByThe light irradiation means can be installed in close contact with the inner wall of the photoconductor, improving the focal position accuracy,Low power consumption, compact and excellent portability, and high-speed recording can be achieved.
[0081]
In addition, since the image forming apparatus of the present invention performs exposure by a method that does not use corona discharge, it does not generate ozone and has excellent environmental resistance.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing an embodiment of a back exposure type image forming apparatus according to the present invention.
2 is a diagram showing a layer structure of a photosensitive drum in the image forming apparatus of FIG. 1. FIG.
FIG. 3A is a perspective view showing an embodiment of the exposure apparatus according to the present invention, and FIG.
FIG. 4 is a view for explaining how to attach an exposure apparatus according to another embodiment of the present invention.
5 is a perspective view (a) showing the configuration of the exposure apparatus in FIG. 4 and a partial cross-sectional view (b) along the line A-A ′ in FIG. 5 (a).
6 is a view for explaining a method of manufacturing a surface emitting laser in the exposure apparatus of FIG. 4; FIG.
FIG. 7 is a partially cutaway side view (a) and an enlarged plan view (b) for explaining another embodiment of the exposure apparatus according to the present invention.
FIG. 8 is a schematic configuration diagram showing an embodiment of a color image forming apparatus according to the present invention.
FIG. 9 is a view showing a conventional example in which a surface emitting laser is used as an exposure apparatus.
FIG. 10 is a diagram showing a conventional example of how light emitting points are arranged in a surface emitting laser array.
FIG. 11 is a cross-sectional view illustrating an example of an image forming apparatus employing conventional backside exposure.
[Explanation of symbols]
1 Photoconductor
2 Exposure equipment (light irradiation means)
20 Transparent support
21 Transparent conductive layer
22 Photoconductive layer
23 Surface layer
30, 72 Surface emitting laser array
31, 50, 70 Mounting board
32, 71 Driver IC
34, 54 luminous point
73 Belt

Claims (1)

A photoconductor provided with a transparent conductor layer and a photoconductor layer in order on a transparent support; and a light irradiation means for irradiating light provided inside the photoconductor,
Image formation in which the light irradiation means irradiates light from the transparent support side to expose the photoconductor layer, and supplies a toner to the exposed portion on the photoconductor layer to form a visible image In the device
The light irradiation means, possess a substrate, and a surface emitting laser that emits light in a vertical direction is provided on the substrate,
The substrate has flexibility, and the surface emitting laser is attached so as to be in close contact with the inner wall of the photoconductor, and all of the epitaxial growth semiconductor substrate used to form the surface emitting laser is removed. an image forming apparatus characterized in that it is.

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