JP2001154502A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device of high image quality which obviates the occurrence of a photo-fatigue memory and image unevenness by elucidating the magnitude relation among the respective light source wavelengths with which a photoreceptor surface is irradiated. SOLUTION: The image forming device has an amorphous silicon photoreceptor, an electrostatic charging means for electrostatically charging the amorphous silicon photoreceptor, an image exposure means for subjecting the amorphous silicon photoreceptor to image exposure in accordance with image information, a developing means for forming toner images, a transfer exposure means disposed in the position of a transfer device for transferring the toner images to the transfer paper or upstream the same, a cleaning means of the amorphous silicon photoreceptor, an erasing exposure means for erasing the electrostatic charging potential of the photoreceptor surface disposed between the cleaning means and the electrostatic charging means. The peak wavelength of the light source of the transfer exposure means described above is made shorter than the peak wavelength of the light source of the erasing exposure means described above.

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 capable of preventing light fatigue memory of an amorphous silicon photoreceptor and preventing density unevenness caused by the light fatigue memory.

[0002]

2. Description of the Related Art In an image forming apparatus, a light source (hereinafter simply referred to as PCL) of an erasing exposure means PCL for erasing and uniformizing the surface potential of a photoreceptor, an image exposure light source, and a light source of a pre-transfer exposure means PTL in normal development. Irradiation of light from a light source (hereinafter simply referred to as PSL), a light source of a simultaneous transfer exposure means TSL in reversal development (hereinafter sometimes referred to simply as TSL), or a light source of a jam detection sensor for jam detection is performed on the photosensitive member. However, when the peak wavelength of each light source such as the jam detection sensor is increased, the electric charge of the surface potential is trapped as a carrier in a deep portion of the photosensitive layer on the surface of the photosensitive member made of amorphous silicon, and the erasing by the erasing exposure unit is performed. Insufficient, and if the next charging is performed as it is,
It becomes difficult for new charges to be placed on the trapped portion, the surface of the photoreceptor is no longer uniformly charged, and the previous history remains in the photo-fatigue memory, which may cause density unevenness. Therefore, it is not preferable to use the transfer exposure or the jam detection sensor of the pre-transfer exposure unit or the simultaneous transfer exposure unit having the light source having a long wavelength. In particular, as image formation speeds up, the time from erasing exposure to the next charge becomes shorter, and the recovery time of light fatigue is shortened, so that light fatigue memory is more likely to occur and the normal state is restored. The next image is formed without performing the above operation, and the location where the light fatigue memory is generated causes a phenomenon of density unevenness, and the image quality is remarkably deteriorated.

Conventionally, the wavelength of a PCL light source has been set to 600 to 700.
nm is specified in JP-A-60-168187, and the wavelength of the PCL light source is 600 nm or more.
An image exposure light source having a wavelength of 700 nm or more is described in JP-A-61-183681, but in order to prevent the occurrence of photo-fatigue memory by an optical sensor for adjusting image density, a light source between the light sources is used. Nothing mentions the effect of wavelength.

[0004]

SUMMARY OF THE INVENTION The present invention solves such a problem, examines the relationship between peak wavelengths between light sources that do not generate light fatigue memory, and finds conditions that do not cause light fatigue memory. Accordingly, it is an object of the present invention to provide an image forming apparatus in which density unevenness does not occur in an image to be formed.

[0005]

This object is achieved by any of the following technical means (1) to (13).

(1) Amorphous silicon photoreceptor, charging means for charging the amorphous silicon photoreceptor, image exposing means for exposing the amorphous silicon photoreceptor to image based on image information, developing means for forming a toner image, and developing means Transfer exposure means provided between transfer devices for transferring the toner image to the transfer paper or at the position of the transfer device, cleaning means for removing toner remaining on the amorphous silicon photoconductor,
An erasing exposure unit for erasing a charged potential on the surface of the amorphous silicon photoreceptor provided between the cleaning unit and the charging unit, wherein the peak wavelength of a light source of the transfer exposure unit is An image forming apparatus having a wavelength shorter than a peak wavelength of a light source.

(2) an amorphous silicon photoreceptor, charging means for charging the amorphous silicon photoreceptor, image exposure means for exposing the amorphous silicon photoreceptor to image based on image information, developing means for forming a toner image by regular development, Pre-transfer exposure means provided between the developing means and a transfer device for transferring a toner image to transfer paper; cleaning means for removing toner remaining on the amorphous silicon photoreceptor;
An erasing exposure unit for erasing a charged potential of the surface of the amorphous silicon photoreceptor provided between the cleaning unit and the charging unit, wherein the light source of the image exposure unit and the light source of the pre-transfer exposure unit are An image forming apparatus, wherein each peak wavelength is shorter than a peak wavelength of a light source of the erasing exposure unit.

(3) The image forming apparatus according to item (2), wherein white light is used as a light source of the image exposure means, and a long wavelength side is cut by a filter.

(4) The light source of the image exposure means is 700 n
The image forming apparatus according to (2) or (3), wherein m or more is cut.

(5) an amorphous silicon photoreceptor, charging means for charging the amorphous silicon photoreceptor, image exposure means for exposing the amorphous silicon photoreceptor to an image based on image information, developing means for forming a toner image by reversal development, Transfer simultaneous exposure means provided in a transfer device for transferring a toner image to transfer paper, cleaning means for removing toner remaining on the amorphous silicon photoconductor, and the amorphous silicon photoconductor provided between the cleaning means and the charging means In an image forming apparatus having an erasing exposure unit for erasing a charged potential on a surface, each peak wavelength of a light source of the image exposure unit and a peak wavelength of a light source of the simultaneous transfer exposure unit is shorter than a peak wavelength of a light source of the erasing exposure unit. An image forming apparatus comprising:

(6) A light emitting diode is used as a light source of the pre-transfer exposure means or the simultaneous transfer exposure means as the transfer exposure means and a light source of the erasure exposure means. The image forming apparatus according to any one of the above items.

(7) The peak wavelength of the light source of the pre-transfer exposure means or the simultaneous transfer exposure means as the transfer exposure means is set to 700 nm or less.
The image forming apparatus according to any one of the above items (6).

(8) The peak wavelength of the light source of the erasing exposure means is set to 700 nm or less.
(7) The image forming apparatus according to any one of the above (7).

(9) Amorphous silicon photoreceptor, charging means for charging the amorphous silicon photoreceptor, image exposure means for exposing the amorphous silicon photoreceptor to an image based on image information, and forming a toner image by normal development or reverse development Developing means, pre-transfer exposure means or transfer simultaneous exposure means as a transfer exposure means provided between or between the development means and a transfer device for transferring a toner image to transfer paper, which occurs on the amorphous silicon photoreceptor A jam detection sensor for detecting a jam of transfer paper, a control unit for performing a jam process based on jam information detected by the jam detection sensor, a cleaning unit for removing toner remaining on the amorphous silicon photoconductor, and the cleaning unit. The charge potential on the surface of the amorphous silicon photoreceptor provided between the charging means is turned off. An image forming apparatus, comprising: an erasing exposure unit that removes light; wherein a peak wavelength of a light source used for the jam detection sensor is shorter than a peak wavelength of a light source of the erasing exposure unit.

(10) The image forming apparatus according to (9), wherein a peak wavelength of a light source of the image exposure unit is shorter than a peak wavelength of a light source of the erasure exposure unit.

(11) The image forming apparatus according to (9) or (10), wherein the jam detection sensor also functions as a density detection sensor for adjusting image density.

(12) The light source used for the jam detection sensor is a light-emitting diode.
(11) The image forming apparatus according to any one of the above (11).

(13) The jam detection sensor utilizes diffused light on the surface of the photoreceptor, (9) to (1).
The image forming apparatus according to any one of the above 2).

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an image forming apparatus according to the present invention will be described first with reference to a schematic configuration diagram shown in FIG.

The image forming apparatus shown in FIG. 1 is a digital type image forming apparatus, and includes an image reading section A, an image processing section B (not shown), an image forming section C, and transfer paper transport as transfer paper transport means. It is composed of a section D.

An automatic document feeder for automatically feeding a document is provided above the image reading section A.
The original placed on the original 1 is moved by the original transport roller 12 to the original
The sheets are separated and conveyed, and the image is read at the reading position 13a. The document for which the reading of the document has been completed is discharged onto the document discharge tray 14 by the document conveying roller 12.

On the other hand, the image of the original placed on the platen glass 13 is read in the form of a V-shape by a reading operation at a speed v of a first mirror unit 15 comprising an illumination lamp and a first mirror constituting a scanning optical system. Reading is performed by moving the second mirror unit 16 including the second mirror and the third mirror located at the speed v / 2 in the same direction.

The read image is formed on a light receiving surface of an image pickup device CCD as a line sensor through a projection lens 17. The line-shaped optical image formed on the image sensor CCD is sequentially photoelectrically converted into an electric signal (brightness signal), and then A
After performing / D conversion and performing processing such as density conversion and filter processing in the image processing unit B, the image data is temporarily stored in the memory.

In the image forming section C, as shown in a schematic diagram showing the arrangement of the respective steps around the photosensitive member in FIG. 2, an amorphous silicon photosensitive member 21 (hereinafter sometimes simply referred to as a photosensitive member) is used as an image forming unit. ), A charger 22 serving as a charging unit, a light incident position Ao from a light source of an image exposure unit 30, a developing unit 23 serving as a developing unit, a transfer unit 24 serving as a transfer unit, and transfer to a transfer sheet. A light source 24L1 of the simultaneous transfer exposure means TSL as a transfer exposure means for smoothly performing transfer and a separator 25 serving as a separation means, and a jam for detecting a jam of transfer paper which can also serve as a density detection sensor for detecting the density of a patch. A detection sensor 28 and its light source 28L, a cleaning unit 26, and a PCL (precharge lamp) 27 as an erasing exposure unit are arranged in the order of operation. The photoconductor 21 is an amorphous silicon photoconductor in which a photoconductive layer mainly composed of, for example, a silicon hydride compound as a photoconductive compound is formed on a drum substrate, and is driven to rotate clockwise in the drawing.

After the rotating photoreceptor 21 is uniformly charged by the charger 22, image exposure based on the recorded image signal recalled from the memory of the image processing unit B is performed by the image exposure means 30. Will be The image exposing means 30, which is a writing means, uses a laser (not shown) as a light emitting light source. The optical path is bent by a reflecting mirror 32 through a rotating polygon mirror 31, an fθ lens (no sign), and a cylindrical lens (no sign), and main scanning is performed. The photoreceptor 21
Is subjected to image exposure at the position of Ao,
A latent image is formed by one rotation (sub-scan).

The latent image on the photoreceptor 21 is reversely developed by a developing device 23 as a developing means, and a visible toner image is formed on the surface of the photoreceptor 21. In the transfer paper transport section D, a paper feed unit 41 serving as a transfer paper storage unit in which transfer papers P of different sizes are stored below the image forming unit.
(A), 41 (B), 41 (C) are provided, and a manual paper feed unit 42 for performing manual paper feed is provided on the side, and the transfer paper P selected from any of them is provided. The transfer paper P is fed by the guide rollers 43 along the transport path 40, and the transfer paper P is temporarily stopped and then transported again by the pair of registration rollers 44 for correcting the inclination and deviation of the fed transfer paper. The toner image on the photoreceptor 21 is guided by the pre-transfer roller 43a and the transfer entry guide plate 46, and is simultaneously irradiated with the transfer at the transfer position Bo by the light source 24L1 of the simultaneous transfer exposure means TSL, and is transferred by the transfer device 24. Transferred to paper P and then to separator 2
5, the transfer paper P is separated from the surface of the photoreceptor 21, and is conveyed to the fixing device 50 by the conveying device 45.

The fixing device 50 has a fixing roller 51 and a pressure roller 52. By passing the transfer paper P between the fixing roller 51 and the pressure roller 52, the transfer paper P is heated and pressed to remove toner. Weld. The transfer paper P on which the toner image has been fixed is discharged onto the discharge tray 64.

The image forming apparatus of the above embodiment is of the digital type and of the reversal developing type, and employs the simultaneous transfer exposure method as means for smoothing the transfer to the transfer paper. In the case of the developing method, a pre-transfer exposure method is used as means for smooth transfer to the transfer paper. In the following description, both the method using the simultaneous transfer exposure means TSL and the use of the pre-transfer exposure means PTL will be described. However, both of the light fatigue memories show almost the same behavior. The transfer simultaneous exposure means TSL and the pre-transfer exposure means PTL are collectively referred to as transfer exposure means.

Hereinafter, the light source 24L1 of the simultaneous transfer exposure means TSL or the light source 24L2 of the pre-transfer exposure means PTL, which is a special feature of the present invention, for smooth transfer to transfer paper and assisting transfer, and for adjusting image density. The prevention of the density unevenness caused by the light fatigue memory caused by the light source 28L of the jam detection sensor 28 for detecting the jam of the transfer paper on the photosensitive member will be described in detail.

As described above, in the image forming apparatus using the amorphous silicon photosensitive member, the light source 24L2 of the pre-transfer exposure means PTL or the transfer simultaneous exposure means TSL
This is a problem because the light fatigue memory in the light source 24L1 has an effect on the image of the next round. This is likely to occur due to long-wavelength light. Charges as carriers remain trapped deep in the photosensitive layer on the surface of the photoreceptor made of amorphous silicon, and the charges as carriers cannot be sufficiently erased as they are. It turned out to be a phenomenon. For example, when an experiment is performed using LEDs having peak wavelengths of 550, 600, 700, and 800 nm, light fatigue memory hardly occurs at 550 nm, and light fatigue memory occurs at 600, 700, and 800 nm. Has been experimentally confirmed to become increasingly significant. It has been found that this occurs because carriers trapped at a deep position are not sufficiently relaxed. Therefore, we found that the following were effective in solving this problem.

First, the light source 24L2 of the pre-transfer exposure means PTL is installed between the developing means 23 for creating a visible image by regular development and the transfer device 24 for transferring the toner image to the transfer paper, and remains on the photosensitive member 21. Cleaning means 26 for removing waste toner
After that, the light source 27 of the erasing exposure unit PCL is installed, and the peak wavelength of the light source 24L2 of the pre-transfer exposure unit PTL is set to be shorter than the peak wavelength of the light source 27 of the erasing exposure unit PCL.

In this manner, the charge as a carrier partially trapped by the light source light of the jam detection sensor 28 at a deep portion of the photosensitive layer is converted into an erasing exposure means which is a uniform exposure light having a longer wavelength. Light source 2 of PCL27
By giving uniform light fatigue to the whole by 7L,
It becomes possible to erase apparent light fatigue memory,
Density unevenness can be suppressed. In other words, when a long wavelength light source irradiates a partial region of the surface of the photosensitive layer made of amorphous silicon, electric charges as carriers from the surface potential remain trapped in a deep portion of the photosensitive layer. When charging for the next cycle is performed, the surface of the photoreceptor is not uniformly charged, and the surface potential of a portion where the charge as a carrier is trapped is reduced, so that a light fatigue memory appears. As a means for solving this, uniform trapping is performed including other portions other than the trapped portion. For this purpose, uniform exposure is performed using a PCL having a long wavelength peak wavelength, and the following process is performed. This is to lead to uniform charging of the cycle.

Second, an image exposing means 30, a light source 24L2 of a pre-transfer exposing means PTL provided between a developing means 23 for forming a toner image by regular development and a transfer device 24 for transferring the toner image to a transfer sheet, Erasing exposure means PCL provided after cleaning means 26 for removing toner remaining on photoconductor 21
27 light sources 27L, and the peak wavelength of the light source 30L of the image exposure means 30 and the peak wavelength of the light source 24L2 of the pre-transfer exposure means PTL are determined by the erasing exposure means PCL2.
7 is shorter than the peak wavelength of the light source 27L.

Third, the simultaneous light exposure of the light source 30L of the image exposing means 30 for producing a latent image and the transfer means 24 provided on the transfer device 24 for transferring the toner image to the transfer paper after the developing means 23 for producing the toner image by reversal development. The light source 24L1 of the means TSL and the photoconductor 2
A light source 27L of the erasing exposure means PCL provided after the cleaning means 26 for removing the toner remaining in 1;
The respective peak wavelengths of the light source 30L of the latent image forming image exposure unit 30 and the light source 24L1 of the transfer and simultaneous exposure unit TSL are set to be shorter than the peak wavelength of the light source 27L of the erasure exposure unit PCL.

In the image forming apparatus using the amorphous silicon photosensitive member 21, a jam detecting sensor 28 for detecting a jam of the transfer paper wound around the photosensitive member is provided. Light source 28
It is necessary to prevent light fatigue memory due to L.

That is, the light source 28L of the jam detection sensor 28 is determined based on the peak wavelength of the light source 27L of the erasing exposure means PCL.
When the peak wavelength is increased, a photo-fatigue memory is generated. Therefore, it has been hesitated to use the jam detection sensor 28 as a means for detecting the jam of the transfer paper wrapped around the photoreceptor 21.

As a countermeasure, the following means were used to eliminate the occurrence of light fatigue memory and the resulting unevenness in density.

(1) Light source 2 of the jam detection sensor 28
When a light emitting diode LED is used as 8L, its peak wavelength is made shorter than the peak wavelength of the light source 27L of the erasing exposure means PCL27.

(2) Light source 2 of the jam detection sensor 28
When an LED is used as 8L, the peak wavelength of the LED and the peak wavelength of the laser light source 30L of the image exposure unit 30 for creating a latent image are set to be shorter than the peak wavelength of the light source 27L of the erasure exposure unit PCL27.

That is, the charges as carriers trapped by irradiation with light of a certain wavelength are eliminated by light having a peak wavelength longer than the peak wavelength. The mechanism is
The carriers trapped by the irradiation of light of a certain wavelength are uniformly trapped over the entire surface of the photoreceptor by irradiation of the light source 27L of the erasing exposure means PCL27 which has a longer wavelength than that wavelength and uniformly exposes the entire surface. It is considered that the entire surface is uniformly fatigued, so that it does not lead to uneven density. When the density becomes low, the density adjustment function is operated by a density detection sensor that is also used by the jam detection sensor.

That is, since the jam detection sensor 28 for detecting the transfer paper wrapped around the photosensitive member can be installed at the same location, it can be used also as a density detection sensor used for adjusting image density.

Each of the light sources is a light emitting diode (LE).
D) is advantageous in terms of the power situation.

When the jam detecting sensor detects a jam, the control means operates to stop the image forming operation of the image forming apparatus, so that the jam clearing operation can be performed accurately.

[0044]

EXAMPLES The following Example 1 and Example 2 were obtained as examples based on the above embodiment, and they are shown below. First, a first embodiment will be described.

Embodiment 1 First, the configuration conditions common to each experiment of Embodiment 1 will be described. (1) The photoreceptor 21 has hydrogenated amorphous silicon in the photosensitive layer, has a thickness of 20 to 100 μm, has a surface layer of amorphous silicon carbide, and has a diameter of 80 mm. (2) The use of the erasing exposure means PCL, the pre-transfer exposure means PTL, and the simultaneous transfer exposure means TSL
Combination of L and PCL, TSL and PCL for reversal development
In addition, it is preferable to use light emitting diodes (LEDs) for these light sources from the viewpoints of cost, electric power, and the like. (3) PTL and TSL are lit only in the image area + α, and PCL is always lit at the time of image formation, in accordance with normal usage. (4) A Konica 7050 modified machine and a 4355 modified machine employing a toner recycling system were used in the experiment. (In the case of reversal development, the modification was performed with a 7050 modified machine, and in the case of regular development, the modification was performed with a 4355 modified machine.) (5) Photoconductor linear speed: 270 mm / sec Developer: 2-component developer using 8 μm toner and 60 μm carrier Conditions: 7050 remodeling machine Vbias 600V, VH 750V 4355 remodeling machine Vbias 120V, VH 750V In the experiment, the peak wavelength of the light source 27L of the erasing exposure means PCL27, the peak wavelength of the light source 24L2 of the pre-transfer exposure means PTL, and the light source of the simultaneous transfer exposure means TSL. The measurement was performed by combining the peak wavelength of 24L1 with the peak wavelength of the light source 30L of the latent image forming image exposure unit 30.

In the experiment, judgment was made based on whether or not light fatigue memory caused by PTL and TSL occurred when five halftone images having an image density of 0.7 were continuously copied. (The light fatigue memory has a higher density than other parts.) The evaluation criteria were as follows. ：: No light fatigue memory was generated. Δ: Light fatigue memory was slightly generated. X: Light fatigue memory was significantly generated. The results are shown in Tables 1, 2 and 3 below.

[0047]

[Table 1]

[0048]

[Table 2]

[0049]

[Table 3]

From the above results, in order to prevent photo-fatigue memory in an image forming apparatus using an amorphous silicon photoreceptor, in order to prevent the light exposure peak value of the light source of the erasing exposure means PCL, the pre-transfer exposure means PTL or the transfer simultaneous exposure means The peak wavelength of the light source of the TSL and the peak wavelength of the light source of the image exposure means could be optimized. The results obtained are summarized as follows.

First, the light source 24L2 of the pre-transfer exposure means PTL is installed between the developing means 23 for creating a visible image by regular development and the transfer device 24 for transferring the toner image to the transfer paper. Cleaning means 26 for removing waste toner
After that, the light source 27L of the erasing exposure means PCL27 is installed,
The peak wavelength of the light source 24L2 of the pre-transfer exposure means PTL is made shorter than the peak wavelength of the light source 27L of the erasure exposure means PCL27.

Second, pre-transfer exposure is performed between the light source 30L of the image exposure means 30 for producing a latent image, the developing means 23 for producing a visible image by regular development, and the transfer device 24 for transferring the toner image to the transfer paper. The light source 24L2 of the means PTL and the light source 27L of the erasing exposure means PCL27 are provided after the cleaning means 26 for removing the toner remaining on the photoreceptor 21, and the peak wavelength of the light source 30L of the image exposure means 30 for forming a latent image is determined. The peak wavelength of the light source 24L2 of the pre-transfer exposure means PTL is made shorter than the peak wavelength of the light source 27L of the erasure exposure means PCL27.

Third, the light source of the image exposing means for creating a latent image and the developing means 23 for creating a visible image by reversal development, and then the transfer simultaneous exposing means TSL to the transfer device 24 for transferring the toner image to transfer paper. After the light source 24L1 and the cleaning means 26 for removing the toner remaining on the photoconductor 21, the erasing exposure means P
CL light source 27L, and a light source 30L of the image exposure means 30 for forming a latent image and the transfer simultaneous exposure means TSL.
Of each peak wavelength of the light source 24L1 of the erasing exposure means PC
The wavelength is set to be shorter than the peak wavelength of the light source 27L of L27.

As described above, it is possible to provide an image forming apparatus having stable performance over a long range without generating light fatigue memory.

Embodiment 2 First, the constituent conditions common to the experiments of Embodiment 2 will be described. (1) The amorphous silicon photoconductor 21 has hydrogenated amorphous silicon in the photosensitive layer and has a film thickness of 20 nm.
１００100 μm, a layer made of amorphous silicon carbide provided on the surface layer, and having a diameter of 80 mm was used. (2) The jam detection sensor 28 for jam detection is LE
A method was employed in which the diffused light of the light irradiated in D was condensed by a phototransistor and converted into a voltage to determine whether or not the transfer paper was wound around the photoreceptor 21. Although it is possible to use an optical sensor using reflected light,
The use of an optical sensor utilizing diffused light is usually preferred and is employed. (3) The light source 27L of the erasing exposure means PCL27 is used as erasing light of the photoconductor surface potential. An LED, a fluorescent lamp, a laser, or the like can be used, and it is preferable to use the LED from the viewpoint of saving power and the like. (4) The wrapping around the photoconductor 21, that is, the lighting timing of the light source 28 L of the jam detection sensor 28 for detecting jam is determined based on the assumption that the transfer paper is wrapped around the photoconductor 21 as shown in the schematic diagram of FIG. 3. The LED is turned on slightly before the front end of the jam detection sensor 2 to detect the jam.
8 is read at the same time as the leading edge of the paper. (5) In the experiment, a Konica 7050 remodeling machine of a reversal development type employing a toner recycling system was used. (6) The photoconductor linear velocity is 270 mm / sec, and the developer is 8
A component developer using a μm toner and a 60 μm carrier was used. (7) The development conditions are Vbias 600V, VH75
0 V was applied.

Under such conditions, the erasing exposure means PCL2
An experiment was conducted by combining the peak wavelength of the LED light source 27L, the peak wavelength of the light source 30L of the image exposure unit 30 for creating a latent image, and the peak wavelength of the light source 28L of the jam detection sensor 28 for detecting a jam.

In the experiment, it was determined whether or not a light fatigue memory caused by the light source 28L of the jam detection sensor 28 occurred when five halftone images having an image density of 0.7 were continuously copied. (The light fatigue memory has a higher density than other parts.) The evaluation criteria were as follows. ：: No light fatigue memory was generated. ：: Light fatigue memory was slightly generated. X: Light fatigue memory was significantly generated. Table 4 shows the results.

[0058]

[Table 4]

From the above results, it has been found that the use of the jam detection sensor 28 as a sensor for detecting the jam around the photoreceptor becomes possible by maintaining the following relationship.

First, by setting the peak wavelength of the LED as the light source 28L used for the jam detection sensor 28 to be shorter than the peak wavelength of the light source 27L of the erasing exposure means PCL27, generation of memory due to light fatigue is suppressed. This has made it possible to use the jam detection sensor 28 with confidence.

Second, the peak wavelength of the LED as the light source 28L used for the jam detection sensor 28 and the peak wavelength of the laser light of the light source 30L of the latent image forming image exposure means 30 are defined as:
By making the wavelength shorter than the peak wavelength of the light source 27L of the erasing exposure means PCL, it is possible to suppress the occurrence of memory due to light fatigue, and the jam detection sensor can be used.

[0062]

According to the image forming apparatus of the present invention, it is possible to eliminate the occurrence of light fatigue memory by clarifying the magnitude relationship between the peak wavelengths of the respective light sources irradiated on the photoreceptor surface, and to reduce the density unevenness. It has become possible to provide an image forming apparatus with high image quality that does not occur. In addition, various sensors can be used with confidence without adversely affecting images.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an example of an embodiment of an image forming apparatus of the present invention.

FIG. 2 is a schematic diagram showing an arrangement of each process around a photoconductor in the present invention.

FIG. 3 is a schematic diagram illustrating lighting timing of a light source of a jam detection sensor.

[Explanation of symbols]

 Reference Signs List 21 amorphous silicon photoreceptor 22 charger 23 developing means (developing device) 24 transfer unit 24L1 light source (transfer simultaneous exposure light source) 24L2 light source (exposure light source before transfer) 25 separator 26 cleaning means 27 erasing exposure means (PCL) 27L light source ( Erasure exposure light source) 28 Jam detection sensor 30 Image exposure means 30L Light source (Image exposure light source) Ao Image exposure light incident position Bo Transfer position TSL Transfer simultaneous exposure means PTL Pre-transfer exposure means

Continued on the front page F-term (reference) 2H027 DA10 DA15 DB07 DC14 DE02 DE07 DE09 EA03 EA08 EA09 EA10 EC06 EC09 ED03 ED07 ED15 ED24 ED26 ED27 2H032 AA02 BA02 BA05 BA11 BA23 BA29 BA30 2H035 BA01 BA02 BA03 BA07 2H068 FA CA03 CA09 CA17 DA09 DA42

Claims (13)

[Claims] An amorphous silicon photoreceptor, a charging unit for charging the amorphous silicon photoreceptor, an image exposing unit for exposing the amorphous silicon photoreceptor to an image based on image information, a developing unit for forming a toner image, and the developing unit. Transfer exposure means provided between transfer devices for transferring a toner image onto transfer paper or at the position of the transfer device; cleaning means for removing toner remaining on the amorphous silicon photoreceptor; provided between the cleaning means and the charging means An erasing exposure unit for erasing the charged potential on the surface of the amorphous silicon photoreceptor, wherein the peak wavelength of the light source of the transfer exposure unit is shorter than the peak wavelength of the light source of the erasing exposure unit. An image forming apparatus comprising: 2. An amorphous silicon photoreceptor, a charging unit for charging the amorphous silicon photoreceptor, an image exposing unit for exposing the amorphous silicon photoreceptor to an image based on image information, a developing unit for forming a toner image by regular development, A pre-transfer exposure means provided between the developing means and a transfer device for transferring a toner image to transfer paper; a cleaning means for removing toner remaining on the amorphous silicon photoreceptor; and a cleaning means provided between the cleaning means and the charging means. An erasing exposure unit for erasing a charged potential on the surface of the amorphous silicon photoreceptor, wherein each peak wavelength of a light source of the image exposure unit and a light source of the pre-transfer exposure unit is set to a peak of the light source of the erasure exposure unit. An image forming apparatus wherein the wavelength is shorter than the wavelength. 3. The image forming apparatus according to claim 2, wherein a white light is used as a light source of the image exposure unit, and a long wavelength side is cut by a filter. 4. The image forming apparatus according to claim 2, wherein a light source of the image exposure unit cuts light of 700 nm or more. 5. An amorphous silicon photoreceptor, charging means for charging the amorphous silicon photoreceptor, image exposing means for exposing the amorphous silicon photoreceptor to an image based on image information, developing means for forming a toner image by reversal development, and transfer A transfer simultaneous exposure unit provided in a transfer unit for transferring a toner image to paper; a cleaning unit for removing toner remaining on the amorphous silicon photoconductor; a surface of the amorphous silicon photoconductor provided between the cleaning unit and the charging unit An erasing exposure unit for erasing the charged potential of the image forming apparatus, wherein each peak wavelength of the light source of the image exposure unit and the light source of the simultaneous transfer exposure unit is shorter than the peak wavelength of the light source of the erasing exposure unit. An image forming apparatus comprising: 6. A light-emitting diode according to claim 1, wherein a light source of said pre-transfer exposure means or said transfer simultaneous exposure means as said transfer exposure means and a light source of said erasure exposure means are used. The image forming apparatus according to claim 1. 7. The method according to claim 1, wherein a peak wavelength of a light source of the pre-transfer exposure unit or the transfer simultaneous exposure unit as the transfer exposure unit is 700 nm or less. Image forming device. 8. The image forming apparatus according to claim 1, wherein a peak wavelength of a light source of said erasing exposure unit is 700 nm or less. 9. An amorphous silicon photoreceptor, charging means for charging the amorphous silicon photoreceptor, image exposure means for exposing the amorphous silicon photoreceptor to an image based on image information, development for forming a toner image by normal development or reversal development Means, pre-transfer exposure means or transfer simultaneous exposure means as transfer exposure means provided between or between the developing means and a transfer device for transferring a toner image to transfer paper, and transfer occurring on the amorphous silicon photoreceptor A jam detection sensor for detecting paper jam, a control unit for performing jam processing based on jam information detected by the jam detection sensor, a cleaning unit for removing toner remaining on the amorphous silicon photoconductor, the cleaning unit and the cleaning unit; Erasing the charged potential on the surface of the amorphous silicon photoconductor provided between the charging means An image forming apparatus comprising an erasing exposure unit, wherein a peak wavelength of a light source used for the jam detection sensor is shorter than a peak wavelength of a light source of the erasing exposure unit. 10. The image forming apparatus according to claim 9, wherein a peak wavelength of a light source of said image exposure means is shorter than a peak wavelength of a light source of said erasure exposure means. 11. The image forming apparatus according to claim 9, wherein said jam detection sensor also functions as a density detection sensor for adjusting image density. 12. The light source according to claim 9, wherein the light source used for the jam detection sensor is a light emitting diode.
The image forming apparatus according to claim 1. 13. The image forming apparatus according to claim 9, wherein said jam detection sensor uses diffused light on the surface of a photoreceptor.