JP2002268308A - Imaging device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize not only space saving around a photoreceptor but also miniaturization of an imaging device by efficiently arranging a solid-state optical writing device and a potential sensor, while preventing the deterioration of image quality caused by environmental change and changes due to aging or the like by using the potential sensor. SOLUTION: This imaging device is equipped with the photoreceptor (1), the optical writing device (3) on which a light-emitting element array (3b) is mounted on a base plate (3c) and a developing machine (5), and also equipped with the potential sensor (4) detecting the surface potential of the photoreceptor between an optical writing position (3f) and a developing position (5f) on the surface of the photoreceptor. The device is constituted such that the sensor (4) is held integrally by the device (3).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a printer, a facsimile machine, etc., and more particularly, to an image forming apparatus having a writing device using a light emitting element array. .

[0002]

2. Description of the Related Art In recent years, as digital output devices such as copiers, printers, and facsimile machines have become smaller, downsizing of writing devices has been required. At present, the writing methods can be roughly classified into two types. One is an optical scanning method in which a light beam emitted from a light source such as a semiconductor laser is optically scanned by a deflector and a light spot is formed by a scanning image forming lens (see FIG. 1B). This is a solid-state scanning method in which a light beam emitted from a light emitting element array such as an array is formed into a light spot by an imaging element array (see FIG. 1A).

In the above-described optical scanning method, the light path length is increased because light is scanned by an optical deflector. On the other hand, in the solid-state scanning method, the optical path length can be made very short. There is an advantage that the whole can be reduced in size, and there is also an advantage that no mechanical driving parts such as an optical deflector are required.

However, conversely, since the optical path length is short, a solid-state scanning type writing device (hereinafter, referred to as a solid-state optical writing device).
In this method, the device is disposed close to the photoconductor, and a wider space near the photoconductor is required as compared with an optical scanning type writing device (hereinafter referred to as an optical scanning device). Therefore, there is no room for the layout of other devices around the photoconductor, for example, a developing device, a charging device, and the like, and for example, the diameter of the photoconductor needs to be larger than that of an image forming apparatus using an optical scanning device. However, there is a problem that the advantage of the solid-state optical writing device that the size of the image forming apparatus can be reduced due to the small size of the writing device itself cannot be fully utilized.

On the other hand, a photosensitive member in an image forming apparatus, and a charging charger, a writing device, a developing device, a transfer / separation device, a cleaning device, and the like disposed around the photosensitive member are used for changing environmental conditions such as temperature and humidity. Contamination of toner or paper powder, or deterioration over time, changes the characteristics and performance of the toner, which may lower the image quality compared to the initial stage.

In order to solve such a problem, the potential of an electrostatic latent image of a reference pattern formed on a photoreceptor is conventionally detected using a potential sensor, and various image forming conditions are determined based on the detected potential. Is known to prevent image quality deterioration (see, for example, Japanese Patent Application Laid-Open No. 10-73975).
According to the publication, the potential sensor is disposed close to the photoreceptor, but is used not only for repair in the event of a failure, but also for replenishing toner, or for an imaging element provided in a solid-state optical writing device. There are many occasions where the developing device and the solid-state optical writing device are detached from the image forming apparatus, such as for cleaning when dust adheres.

However, if the potential sensor holding member occupies a large space or crawls a long distance, the detachability may be affected. In addition, the potential sensor usually needs to be insulated and held due to its mechanism. From the viewpoint of cost, the holding member is usually made of resin, but naturally, the holding member needs to have a predetermined rigidity or more. It has to be thick to some extent. On the other hand, if the thickness is increased, more space is required around the photoconductor (see FIG. 1C). Preferably, the electric field at the time of developing the toner particles by the developing device is an alternating electric field.

[0008]

SUMMARY OF THE INVENTION The present invention is directed to a solid-state optical writing device and a potential sensor which use the potential sensor to prevent the deterioration of image quality due to environmental changes and changes over time. It is an object of the present invention to provide a process cartridge which efficiently arranges the image forming apparatus to save space around the photoreceptor and further downsize the image forming apparatus.

[0009]

According to a first aspect of the present invention, there is provided a photoreceptor, an optical writing device having a light emitting element array mounted on a substrate, and a developing device. Image forming apparatus, further comprising a potential sensor for detecting a photoconductor surface potential between an optical writing position and a developing position on the photoconductor surface, wherein the potential sensor is integrated with the optical writing device or the developing device. The configuration is maintained.

Further, according to the present invention, there is provided an optical writing device in which a photoreceptor and a light emitting element array are mounted on a substrate.
An image forming apparatus provided with a developing device, comprising: a potential sensor for detecting a photoconductor surface potential between an optical writing position on the photoconductor surface and a developing position; The light emitting element is mounted so as to be located at a position deviated from the center in the lateral direction.

According to the third aspect of the present invention, there is provided the second aspect.
In the image forming apparatus described above, the side where the distance from the light emitting point to the end face in the lateral direction of the substrate is long is disposed facing the developing device with respect to the optical axis.

Further, according to the present invention, there is provided an optical writing device in which a photoreceptor and a light emitting element array are mounted on a substrate.
An image forming apparatus including a developing device, a potential sensor for detecting a photoconductor surface potential between an optical writing position on the photoconductor surface and a developing position, and emitted from the light emitting element array to irradiate the photoconductor. The optical writing device was configured so that the optical axis of the light beam was inclined with respect to the normal line of the photoconductor passing through the light irradiation point on the photoconductor.

According to the fifth aspect of the present invention, the fourth aspect of the present invention is provided.
In the invention described above, the optical axis is inclined toward the developing device with respect to the normal line of the photoconductor passing through the light irradiation point on the photoconductor.

According to a sixth aspect of the present invention, there is provided an image forming apparatus including a plurality of image forming units each including a photosensitive member, an optical writing device, and a developing device.
The image forming apparatus according to any one of the above items is provided as one or more image forming units.

Further, according to the invention of claim 7, according to claim 1,
The invention according to any one of claims 6 to 6, wherein an alternating electric field is applied when developing the latent image written on the photosensitive member by the optical writing device.

According to the invention described in claim 8, in claim 1,
7. The image forming apparatus according to claim 1, wherein the image forming apparatus includes a charging device and a cleaning device, and integrally supports the photoconductor and at least one of the charging device, the developing device, and the cleaning device. In addition, a process cartridge which is detachable from the image forming apparatus main body is provided.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows the configuration of the first embodiment of the present invention. With such a configuration, the photoconductor 1 rotates in the direction indicated by the arrow, is charged by the charger 2, is written by the solid-state optical writing device 3 at the writing position 3f, and is developed by the developing device 5 at the developing position 5f. Through the process of doing. The potential sensor 4 is located between the solid-state optical writing device 3 and the developing device 5. The potential sensor 4 detects the potential of the electrostatic latent image of the reference pattern formed on the photoreceptor 1 and controls various image forming conditions based on the detected potential to change the environment and change with time. It is possible to prevent the image quality from deteriorating due to the above.

Further, the potential sensor 4 is integrally held by the solid-state optical writing device 3 by a holding member, thereby creating a space 10 as compared with, for example, the conventional configuration example of FIG. 1C. Accordingly, the solid-state optical writing device 3 can be attached and detached in a direction away from the photoconductor 1 very smoothly. Also,
Due to the space 10, for example, a heat sink 3e for radiating heat generated in the solid-state optical writing device 3 is extended to the space 10 to enhance the heat radiation effect, to reduce the thickness of the heat sink 3e, and to reduce the air flow. And also enhance the heat radiation effect, or move the developing device 5 to the space 10
It is possible to obtain benefits in various forms, for example, by increasing the amount of toner replenishment at one time.

FIG. 3 shows a second embodiment of the present invention. The potential sensor 4 is integrally held on the developing device 5 by a holding member, thereby forming a space 10. Space 10
Provides the same advantage as the space 10 in FIG.

FIG. 4 shows a third embodiment of the present invention. In FIG. 4, the light emitting point 12 is located at the center 1 in the short direction of the substrate 3c.
The light-emitting element 3b is mounted so as to be located at a position shifted by a distance t from the light-emitting element 1, and the side where the distance from the light-emitting point 12 to the end face in the short direction of the substrate 3c is longer on the developing device 5 side than the optical axis 13 Facing. Here, for comparison, the sectional area of the solid-state optical writing device 3 is not changed from that of FIG.
As a result, the expected angle of the solid-state optical writing device (including the potential sensor) from the center of the photoreceptor is reduced by β in FIG. 4 compared to, for example, α in FIG. Creates space. Thereby, for example, the space between the charger 2 and the solid-state optical writing device 3 is reduced by the angle β,
If the diameter of the photoconductor 1 is reduced accordingly, the size of the image forming apparatus can be reduced.

FIG. 5 shows a fourth embodiment of the present invention. In FIG. 5, the write position 3 is different from that of FIG.
The optical axis 13 of the solid-state optical writing device 3 is arranged at an angle θ to the developing device 5 side with respect to the normal line 14 of the photoconductor passing through the writing position 3f without changing f. Thus, in FIG. 5, the expected angle of the solid-state optical writing device 3 (including the potential sensor 4) from the center of the photoconductor 1 is reduced by γ as compared with, for example, α in FIG. A space is created around the photoconductor by an amount of γ. Thus, for example, by filling the space between the charger 2 and the solid-state optical writing device 3 by the angle γ and reducing the diameter of the photoconductor 1 by that amount, the size of the image forming apparatus can be reduced.

FIG. 6 shows a fifth embodiment of the present invention. FIG. 6 shows an image forming apparatus called a tandem type which is advantageous for high-speed color image output. At the lower part of the apparatus, a paper feed cassette 16 arranged in a horizontal direction is provided, and a transport belt 17 for transporting the transfer paper fed from the paper feed cassette 16 is provided. On the conveyor belt 17, the photoconductor 1Y for yellow (Y) and the photoconductor 1 for magenta (M)
M, photoconductor 1C for cyan (C), and black (K)
Photoconductors 1K are arranged at regular intervals from the upstream side. Around these photoconductors 1Y, 1M, 1C and 1K,
Process members according to the electrophotographic process are arranged in order. Taking the photoconductor 1Y as an example, a charger 2Y, an optical writing device 3Y, a developing device 5Y, a transfer device 6Y, and the like are arranged in this order. The same applies to the other photoconductors 1M, 1C, and 1K. Around the transport belt 17, the charge removing device 18 and the cleaning device 8 are positioned downstream of the photoconductor 1 </ b> K.
And so on. A fixing device 19 is provided downstream of the static eliminator 18 in the transport direction, and is conveyed to a discharge tray (not shown) via a discharge roller 20.

In such a tandem type image forming apparatus, for example, if the fourth embodiment of the present invention shown in FIG. 5 is applied to all of the image forming sections K, C, M and Y, the entire image forming apparatus Not only can be reduced in size, but also image forming conditions can be controlled by using surface potential sensors in all four image forming units, and a high quality color image can be obtained.

For example, if the fourth embodiment of the present invention shown in FIG. 5 is applied only to the image forming section K, and if no surface potential sensors are mounted on C, M, and Y, the entire image forming apparatus Since the amount of change in the image forming conditions due to the environmental change can be detected by the surface potential sensor of the image forming unit K, if this is applied to the other image forming units C, M, and Y, respectively, all four image forming units And high quality images can be obtained. With this configuration, it is only necessary to provide one surface potential sensor for the four image forming units, so that the cost can be reduced, and the image forming units C, M, and Y are not provided because the surface potential sensor is not provided. The size can be further reduced, and the size of the entire image forming apparatus can be further reduced.

FIG. 7 shows a sixth embodiment of the present invention. In the developing device 5 shown in FIG. 7, at the time of development, an oscillating bias voltage in which an AC voltage is superimposed on a DC voltage is applied to the developing sleeve 5b as a developing bias by the power supply 15. The background portion potential and the image portion potential are located between the maximum value and the minimum value of the vibration bias potential. Thereby, the developing unit 5c
Thus, an alternating electric field whose direction changes alternately is formed. The developer toner and carrier vibrate violently in this alternating electric field,
The toner flies off the photoconductor 1 by shaking off the electrostatic restraining force on the developing sleeve 5b and the carrier, and adheres to the latent image on the photoconductor 1.

The difference between the maximum value and the minimum value of the oscillation bias voltage (
The peak-to-peak voltage is preferably 0.5 to 5 KV, and the frequency is preferably 1 to 10 KHz. As the waveform of the oscillation bias voltage, a rectangular wave, a sine wave, a triangular wave, or the like can be used. As described above, the DC voltage component of the vibration bias is a value between the background portion potential and the image portion potential. However, a value closer to the background portion potential than the image portion potential is more likely to cover the background portion potential region. From the viewpoint of preventing the adhesion of the toner,

When the waveform of the oscillation bias voltage is a rectangular wave,
It is desirable to set the duty ratio to 50% or less. Here, the duty ratio is the ratio of the time during which the toner goes to the photoconductor during one cycle of the vibration bias. By doing so, the difference between the peak value of the toner going to the photoreceptor and the time average value of the bias can be increased, so that the movement of the toner is further activated, and the potential of the toner on the latent image surface is increased. It adheres faithfully to the distribution and can improve roughness and resolution. Also, since the difference between the peak value of the carrier having the opposite polarity to the toner and the time average value of the bias toward the photoreceptor can be reduced, the motion of the carrier is calmed down, and the background portion of the latent image is reduced. Can significantly reduce the probability that the carrier adheres to the substrate.

FIG. 8 shows a seventh embodiment of the present invention.
In FIG. 8, the above-described photoconductor 1, charging device 2, and developing device 5
And a plurality of components such as the cleaning unit 8 are integrally connected as a process cartridge 21. The process cartridge 21 is a main body of an image forming apparatus such as a copying machine or a printer. It is configured to be detachable with respect to.

In the image forming apparatus according to the seventh embodiment shown in FIG. 8, the photosensitive member 1 is driven to rotate at a predetermined peripheral speed. In the rotation process, the photosensitive member 1 is uniformly charged with a predetermined positive or negative potential on its peripheral surface by the charger 2, and then receives image exposure light from the solid-state optical writing device 3.
An electrostatic latent image is sequentially formed on the peripheral surface of the photosensitive drum 1, and the formed electrostatic latent image is then toner-developed by the developing device 5, and the developed toner image is transferred from the sheet feeding section to the photosensitive member 1 and the transfer device. The transfer unit 6 sequentially transfers the transfer paper 6 to the transfer paper 7 fed in synchronization with the rotation of the photoconductor 1 between the transfer paper 6 and the transfer paper 6. The transfer paper 7 that has undergone the image transfer is separated from the photoreceptor surface, introduced into an image fixing device, where the image is fixed, and printed out of the apparatus as a copy (copy). After the transfer of the image, the surface of the photoreceptor 1 is cleaned by a cleaning device 8 to remove the transfer residual toner, and after being subjected to static elimination, it is repeatedly used for image formation. Here, the solid-state optical writing device 3 and the potential sensor 4
The same components as those of the first embodiment of the present invention shown in FIG. 2 are used, and the same operation as that of the first embodiment is performed.

[0031]

As described above, according to the present invention,
According to the first aspect of the present invention, there is provided a potential sensor for detecting a surface potential of the photosensitive member between the optical writing position and the developing position on the surface of the photosensitive member, and the potential sensor is integrated with the optical writing device or the developing device. Since it is retained, using a potential sensor prevents image quality deterioration due to environmental changes, temporal changes, etc.,
Space saving around the photoreceptor and downsizing of the image forming apparatus can be realized, and detachability of the solid-state optical writing device or the developing device can be improved.

According to the second aspect of the present invention, there is provided a potential sensor for detecting the surface potential of the photosensitive member between the optical writing position and the developing position on the surface of the photosensitive member, and the light emitting point is located from the center in the short direction of the substrate. Since the light emitting element is mounted so as to be located at a shifted position, it is possible to further enhance the effect of the first aspect of the present invention.

According to the third aspect of the present invention, there is provided the second aspect.
2. The image forming apparatus according to claim 1, wherein the side having a longer distance from the light emitting point to the end face in the short direction of the substrate is disposed toward the developing device with respect to the optical axis, so that the invention according to claim 1 is more effectively achieved. The effect can be obtained.

According to the fourth aspect of the present invention, a potential sensor for detecting the surface potential of the photosensitive member between the optical writing position and the developing position on the photosensitive member surface is provided, and emitted from the light emitting element array to irradiate the photosensitive member. The optical writing device is provided such that the optical axis of the light beam is inclined with respect to the normal line of the photoconductor passing through the light irradiation point on the photoconductor. It becomes possible to do.

According to the fifth aspect of the present invention, in the fourth aspect,
In the invention described, since the optical axis is inclined toward the developing device side with respect to the normal line of the photoconductor passing through the light irradiation point on the photoconductor,
The effect of the invention described in claim 1 can be more effectively obtained.

According to a sixth aspect of the present invention, there is provided an image forming apparatus including a plurality of image forming units each including a photosensitive member, an optical writing device, and a developing device.
Since at least one image forming apparatus according to any one of the first to fifth aspects is provided as the image forming unit, the effects of any one of the first to fifth aspects of the present invention can be realized by a color image forming apparatus.

According to the seventh aspect of the present invention, in the first aspect,
In the invention according to any one of claims 6 to 6, since an alternating electric field is applied when developing the latent image written on the photoreceptor, a high-definition image without roughness can be obtained.

Further, in the invention according to claim 8, according to claim 1,
7. In the invention according to any one of items 1 to 6,
At least one of the charging device, the developing device, and the cleaning device is integrally supported and is a process cartridge detachable from the image forming apparatus main body. The image forming apparatus used can be realized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a main part of an image forming apparatus showing an example of a conventional technique.

FIG. 2 is an explanatory diagram of a main part of the image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a main part of an image forming apparatus according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of a main part of an image forming apparatus according to a third embodiment of the present invention.

FIG. 5 is an explanatory diagram of a main part of an image forming apparatus according to a fourth embodiment of the present invention.

FIG. 6 is an explanatory diagram of a main part of an image forming apparatus according to a fifth embodiment of the present invention.

FIG. 7 is an explanatory diagram of a main part of an image forming apparatus according to a sixth embodiment of the present invention.

FIG. 8 is an explanatory diagram of a main part of an image forming apparatus according to a seventh embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoreceptor 2 Charger 3 Solid-state optical writing device 3a Imaging element 3b Light-emitting element 3c Substrate 4 Potential sensor 5 Developing device 9 Optical scanning device 10 Space 11 Center in short side direction of substrate 12 Light emitting point 13 Optical axis 14 Normal line 17 Transport Belt 21 process cartridge

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/04 15/08 507 (72) Inventor Koji Masuda 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Hirokatsu Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Masahiro Ito 1-36 Nakamagome, Ota-ku, Tokyo Ricoh Company F term (reference) 2C162 AE28 FA04 FA17 FA23 FA42 2H030 AA06 AA07 AB02 BB02 2H071 BA13 DA02 DA08 DA32 EA04 2H076 AB42 AB60 2H077 BA09 BA10

Claims (8)

[Claims] 1. An image forming apparatus comprising a photoconductor, an optical writing device having a light emitting element array mounted on a substrate, and a developing device, wherein an optical writing position on the surface of the photoconductor is between the developing position. An image forming apparatus comprising: a potential sensor for detecting a photoconductor surface potential; wherein the potential sensor is integrally held by the optical writing device or the developing device. 2. An image forming apparatus comprising a photosensitive member, an optical writing device having a light emitting element array mounted on a substrate, and a developing device, wherein an optical writing position on the surface of the photosensitive member and a developing position are provided. An image forming apparatus comprising: a potential sensor for detecting a surface potential of a photoreceptor; and a light emitting element mounted on the optical writing device such that a light emitting point is located at a position deviated from a center of a substrate in a lateral direction. . 3. The image forming apparatus according to claim 2, wherein
An image forming apparatus, wherein a side having a long distance from a light emitting point to an end face in a short direction of a substrate is arranged to face a developing device with respect to an optical axis. 4. An image forming apparatus comprising a photosensitive member, an optical writing device having a light emitting element array mounted on a substrate, and a developing device, wherein an optical writing position on the photosensitive member surface and a developing position are provided. The optical writing device includes a potential sensor that detects a surface potential of the photoconductor, and the optical axis of a light beam emitted from the light emitting element array and applied to the photoconductor passes through the light irradiation point on the photoconductor. An image forming apparatus characterized by being inclined with respect to a normal line. 5. The image forming apparatus according to claim 4, wherein
An image forming apparatus, wherein the optical axis is inclined toward a developing device with respect to a normal line of the photoconductor passing through the light irradiation point on the photoconductor. 6. An image forming apparatus including a plurality of image forming units each including a photoconductor, an optical writing device, and a developing device.
6. An image forming apparatus, comprising: at least one image forming apparatus according to claim 1 as said image forming unit. 7. The image forming apparatus according to claim 1, wherein an alternating electric field is applied when a latent image written on said photosensitive member by said optical writing device is developed. An image forming apparatus. 8. The image forming apparatus according to claim 1, wherein the image forming apparatus includes a charger and a cleaning device, and includes a photosensitive member, a charging device, a developing device, and a cleaning device.
An image forming apparatus, comprising: a process cartridge that integrally supports at least one of the coating devices and is detachable from the image forming apparatus main body.