JPH09156155A - Imaging system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a color image in which the color is balanced by providing an optical sensor for detecting the exposure at an end part of an image exposing means arranged with a plurality of light emitting elements in line and controlling the exposure through the optical sensor thereby correcting fluctuation in the quantity of light for each image exposing means. SOLUTION: Reference light emitting elements 121a, 121b emit light of a specified control quantity of light for every specified number of copy sheets, e.g. 10 sheets, at every specified copy cycle, e.g. 10 copy cycle, and optical sensors S1, S2 measure the quantity of light emitted from these elements. The quantity of light is then corrected based on the quantity of light emitted from the reference light emitting elements 121a, 121b and measured by means of the optical sensors S1, S2 and a quantity of light control section controls the light emitting element 121c in an image region S to emit light. Quantity of light is corrected by emission time control for controlling the pulse width of light emitting element 121C. luminance modulation for controlling the quantity of current, etc.

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 a copying machine, a printer, and a FAX, and particularly preferably, an image forming apparatus is provided with a plurality of charging means, image exposing means and developing means around the image forming body. The present invention relates to an electrophotographic color image forming apparatus that forms a color image by superposing toner images during one rotation of a formed body.

[0002]

2. Description of the Related Art Conventionally, as a method for forming a multicolor image, a single color formed on each image forming body is provided with an image forming body, a charging means, a developing means and the like, which are the same in number as the colors necessary for the image formation. Image forming apparatus for forming a color image by superimposing the toner image on the transfer material to form a color image, and a color image forming apparatus for forming a color image by rotating an image forming body a plurality of times and repeating charging, image exposure and development for each color. Alternatively, there is also known a color image forming apparatus that forms a color image by sequentially performing charging, image exposure and development for each color within one rotation of the image forming body.

However, each of the image forming apparatuses described above is provided with the same number of image forming members, charging means, developing means and the like as the number of colors required for image formation, and a single color toner image formed on each photoconductor is superposed on a transfer material. A color image forming apparatus that produces a color image has the drawback of increasing the volume of the apparatus because it requires the conveyance of multiple image forming bodies and transfer materials.On the other hand, the image forming body is rotated multiple times to charge each color. , A color image forming apparatus that forms a color image by repeating image exposure and development is
Although the volume is reduced, there is a restriction that the size of the formed image is limited to the surface area of the photoconductor or less.

In view of this, a color image forming apparatus that forms a color image by sequentially performing charging, image exposure and development for each color within one rotation of the image forming body has no limitation on the size of the image and is a high-speed image. There are advantages such as enabling formation.

[0005]

An image forming apparatus having an image exposing means in which a plurality of light emitting elements for performing image exposure on an image forming body are linearly arranged (especially, one rotation of the image forming body described above). (An image forming apparatus for forming an image by superposing toner images by sequentially performing charging, image exposure and development for each color within)
The light amount of the plurality of light emitting elements provided in the image exposure unit used in the above changes due to the frequency of use and temperature fluctuations due to heat generation of the light emitting elements. Particularly, in an image forming apparatus that forms an image by superimposing toner images, a color image having a color imbalance is formed.

An object of the present invention is to improve and solve the above problems.

[0007]

An object of the present invention is to provide an image forming apparatus having an image exposing means in which a plurality of light emitting elements for performing image exposure on an image forming body are linearly arranged. This is achieved by an image forming apparatus characterized in that an optical sensor for detecting the exposure amount of the end portion is provided, and the exposure amount is controlled by the optical sensor.

[0008]

Embodiments of the present invention will be described below. Note that the description in this section does not limit the technical description of the claims or the meaning of the terms. Also, the following assertive description in the embodiment of the present invention indicates the best mode, and does not limit the meaning of the terms of the present invention or the technical scope.

The image forming process and each mechanism of the color image forming apparatus according to the embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention, and FIG.
FIG. 3 is an enlarged cross-sectional view of a main part of the image exposure unit in FIG. 1, FIG. 3 is a perspective view of FIG. 2, and FIG. 4 is a view showing light quantity control of a light emitting element.

The color image forming apparatus according to the present embodiment uses a photosensitive drum having an electrically conductive layer and a photosensitive layer provided on the outer peripheral surface of a transparent substrate as an image forming body, and is provided inside the photosensitive drum. This is a structure in which the image exposure means is arranged, and the image forming process means such as a charging means, a developing means, a transfer device, a static eliminator and a cleaning device are arranged outside.

The photosensitive drum 10, which is an image forming body, is provided with a cylindrical substrate formed of a transparent member of transparent acrylic resin inside, and a transparent conductive layer, an a-Si layer or an organic photosensitive layer (OPC). ) Is formed on the outer circumference of the substrate, and is rotated clockwise in the state of being grounded as shown by the arrow in FIG.

In the present embodiment, it is sufficient that the photoconductive layer of the photosensitive drum has an exposure light amount capable of imparting an appropriate contrast. Therefore, the light transmittance of the transparent substrate of the photosensitive drum in this embodiment does not need to be 100%, and may have a characteristic that some light is absorbed when the exposure beam is transmitted. As the material of the translucent substrate, an acrylic resin, particularly one polymerized using methyl methacrylate monomer, has transparency, strength, accuracy,
Acrylic, fluorine used for other general optical members, etc.
Various translucent resins such as polyester, polycarbonate, and polyethylene terephthalate can be used. The light-transmitting conductive layer was made of indium tin oxide (ITO), tin oxide, lead oxide, indium oxide, copper iodide, Au, Ag, Ni, Al, etc. A metal thin film is used, and as a film forming method, a vacuum vapor deposition method, an active reaction vapor deposition method, various sputtering methods, various CVs.
D method, dip coating method, spray coating method and the like are used.
Further, as the photoconductor layer, amorphous silicon (a
-Si) alloy photosensitive layer, amorphous selenium alloy photosensitive layer, and various organic photosensitive layers (OPC) can be used.

The scorotron charger 11, which is a charging means, is used in the image forming process of each color of yellow (Y), magenta (M), cyan (C) and black (K), and the above-mentioned organic photosensitive of the photosensitive drum 10 is used. The body layer is charged by a control grid held at a predetermined potential and a corona discharge by a discharge wire to give a uniform potential to the photoconductor drum 10.

The exposure unit 12 as an image exposing means for each color has an FL (phosphor emission), an EL (electroluminescence), and a PL (plasma discharge) arranged in the main scanning direction in parallel with the axis of the photosensitive drum 10. , A linear exposure element 12a in which a plurality of light emitting element units 121 such as LEDs (light emitting diodes) are arranged in an array, and a SELFOC lens 12b as an equal-magnification imaging element, an exposure element 12a,
The unit is configured as a unit attached to a holding member 12c that holds a SELFOC lens 12b as a unity-magnification imaging element, and is attached to a fixing member 20 that holds the exposure unit 12 provided inside the photosensitive drum 10. The image signals of the respective colors stored in the memory are sequentially read out from the memory and input to the exposure unit 12 for the respective colors as electric signals. The emission wavelength of the light emitting device used in this embodiment is in the range of 600 to 900 nm.

The developing device 13, which is a developing means for each color, contains one-component or two-component developers of yellow (Y), magenta (M), cyan (C) and black (K), and is exposed to light. A developing sleeve 131 is provided which rotates in the same direction with a predetermined gap from the peripheral surface of the body drum 10.

The developing device 13 for each of the colors described above applies the developing bias voltage to the electrostatic latent image formed on the photosensitive drum 10 formed by the charging by the scorotron charger 11 and the image exposure by the exposure unit 12. Reverse development is performed in a non-contact state by a non-contact developing method.

As the original image, an image read by an image pickup device of an image reading apparatus separate from this apparatus or an image edited by a computer is temporarily stored as an image signal for each color of Y, M, C and K. Store and store in.

At the start of image recording, a photoconductor drive motor (not shown) is rotated to rotate the photoconductor drum 10 in the clockwise direction shown by the arrow in FIG. The charging action of the scorotron charger 11 starts to apply a potential to the photoconductor drum 10.

After the potential is applied to the photosensitive drum 10, the exposure unit 12 for Y starts exposure by an electric signal corresponding to the first color signal, that is, the image signal for Y, and the surface of the photosensitive drum 10 is exposed by the rotational scanning of the drum. An electrostatic latent image corresponding to the Y image of the original image is formed on the layer.

The latent image is subjected to reversal development by the Y developing device 13 with the developer on the developing sleeve in a non-contact state, and a yellow (Y) toner image is formed according to the rotation of the photosensitive drum 10.

Next, the photoconductor drum 10 is charged on the yellow (Y) toner image by a charging action of a magenta (M) scorotron charger 11 arranged on the left side of the photoconductor drum 10 and above Y. Exposure is performed by an electric signal corresponding to the second color signal of the M exposure unit 12, that is, the image signal of M, and the yellow (Y) color is developed by non-contact reversal development by the developing unit 13 of M. A magenta (M) toner image is sequentially superposed on the toner image.

A cyan (C) scorotron charger 1 disposed on the photosensitive drum 10 by the same process.
Further, the cyan (C) toner image corresponding to the third color signal is generated by the exposure units 12 of C and C and the developing unit 13 of C, and the black (K) color image is disposed below the C on the right side of the photosensitive drum 10. ), A black (K) toner image corresponding to the fourth color signal is sequentially superposed by the scorotron charger 11, the exposure unit 12, and the developing device 13, and the peripheral surface of the photosensitive drum 10 is rotated within one rotation. A color toner image is formed on top.

These Y, M, C and K exposure units 1
The exposure of the organic photosensitive layer of the photoconductor drum 10 by 2 is performed through the above-mentioned transparent substrate from the inside of the drum. Therefore, the exposure of the images corresponding to the second, third, and fourth color signals is performed without any influence from the previously formed toner image, and the same exposure as the image corresponding to the first color signal is performed. It is possible to form an electrostatic latent image.

Developers for replenishing each color are replenished from the replenishing tank 81 to the developing device 13 for the corresponding color, and the developing sleeve 13a.
Supplied to The developing device 13 has a predetermined value, for example, 100 μm to 1 with respect to the photosensitive drum 10 by an abutting roller (not shown).
The developing sleeve 13 is maintained in a non-contact state with a gap of 000 μm, and the developing sleeve 13 is used for the developing action of the developing device 13 for each color.
A developing bias in which a direct current or an alternating current is further applied to a is applied, jumping development is performed by a one-component or two-component developer accommodated in the developing device, and the transparent conductive layer is grounded to the photosensitive drum 10. Non-contact reversal development is performed in which a DC bias having the same polarity as that of the toner is applied to attach the toner to the exposed portion.

A transfer sheet P, which is a transfer material, is sent out from a paper feed cassette 15 which is a transfer material storage means, and is conveyed to a timing roller 16. The color toner image formed on the peripheral surface of the photoconductor drum 10 is transferred to the photoconductor drum 10 by driving the timing roller 16 in the transfer device 14a.
It is transferred onto a transfer paper P which is a transfer material that is fed in synchronization with the above toner image.

The transfer paper P on which the toner image has been transferred is discharged from the drum peripheral surface in the static eliminator 14b and separated from the peripheral surface of the drum, and is then transported to the fixing device 17 by the transport belt 14e which is a transport means. After being heated and pressed in the fixing device 17 to fuse and fix the toner on the transfer paper P, the toner is discharged from the fixing device 17, conveyed by a pair of discharge conveyance rollers 18 a, and is transferred to the upper tray of the apparatus via the discharge rollers 18. Is discharged with the toner image surface facing down.

On the other hand, the photosensitive drum 10 from which the transfer paper is separated
Is rubbed against the surface of the photoconductor drum 10 by the cleaning blade 19a in the cleaning device 19 to remove and clean the residual toner and continue to form the toner image of the original image, or temporarily stop the toner image of a new original image. Formation. The waste toner scraped off by the cleaning blade 19a and the cleaning roller 19b is discharged to the waste toner container 82 through the toner transport screw 19c and the toner transport pipe 19d.
After the cleaning is completed, the cleaning blade 19a and the cleaning roller 19b are kept apart from the photoconductor drum 10 in order to prevent damage to the photoconductor drum 10.

The exposure element 12a is composed of a light emitting element unit 121, for example, a plurality of LEDs arranged linearly on a substrate 122 made of, for example, ceramics. Further, the SELFOC lens 12b and the exposure element 12a are respectively fixed to the holding member 12c with an adhesive indicated by a black circle, and the exposure unit 12 is configured. The exposure unit 12 for each color is arranged parallel to the axis of the photoconductor drum 10 (in the main scanning direction), and is attached to the fixing member 20 with, for example, a screw or an adhesive.

The light emitting element unit 121 is a unit in which a plurality of light emitting elements are linearly arranged.
A plurality of light emitting elements 121c corresponding to the image area S of the photoconductor drum 10 and light emitting elements 121 at both ends outside the image area S
a and 121b (hereinafter referred to as reference light emitting elements). Optical sensors S1 and S2 are provided on both end surfaces on the light irradiation side of the SELFOC lens 12b constituting the image exposure means, corresponding to the reference light emitting elements 121a and 121b. It is provided. Optical sensor S1,
S2 is a Selfoc lens 12b which constitutes an image exposure means.
It may be provided on both end faces of the light emitting element side (light incident side) of the above, or may be provided on the exposure element 12a constituting the image exposure means corresponding to the optical sensors S1 and S2. Also,
A plurality of reference light emitting elements measured by the light sensor may be provided, and the reference light emitting element and the light sensor pair may be provided on only one side of the exposure unit 12 as the image exposing means.

For example, the reference light emitting elements 121a and 121b are caused to emit light with a predetermined light amount control amount for each predetermined copy number such as 1 copy and 10 copies, or for each predetermined copy cycle such as 1 copy cycle and 10 copy cycles, and the reference light emission is performed. The exposure amount of the elements 121a and 121b is measured by the optical sensors S1 and S2, and the light amount is corrected based on the emitted light amounts of the reference light emitting elements 121a and 121b measured by the optical sensors S1 and S2, and the light emitting elements in the image area S are corrected. The light amount control unit controls so that 121c is emitted.
The light amount correction is performed by light emission time for controlling the pulse width of the light emitting element 121c, brightness modulation for controlling the current amount, or the like.

Further, in order that the reference light emitting elements 121a and 121b and the light emitting element 121c in the image area S have the same deterioration, a plurality of light emitting elements 121c are formed as an average value of the emitted light amount. Light emitting element 1
21c, the average number of times of lighting is calculated, and the reference light emitting elements 121a and 121b are set to the above-mentioned average number of times when, for example, a predetermined number of copies, a predetermined copy cycle is completed, or a color image forming apparatus is turned on. The light amount control unit controls so that the reference light emitting devices 121a and 121b are forcibly deteriorated by lighting the same number of times and the reference light emitting amount of the reference light emitting devices 121a and 121b is corrected.

Further, temperature sensors T1, T2, T3 are provided on the substrate 122 of the exposure element 12a, and the temperature sensors T1, T2
The above-mentioned optical sensors S1 and S2 for the measured temperatures of 2 and T3.
If the amount of light emitted from the reference light emitting elements 121a and 121b measured in step 2 is abnormally low or too high, for example, a warning is displayed on an operation unit (not shown), and the color image forming apparatus is stopped at the same time. The light amount control unit controls so as to perform a treatment such as performing.

Further, when the heaters H1 and H2 as heating means are provided on the substrate 122 of the exposure element 12a, and the temperature inside the apparatus detected by the temperature sensors T1, T2 and T3 is low when the color image forming apparatus is turned on, The heaters H1 and H2 as heating means are brought into a heated state, and the substrate 122 is controlled to be heated to a predetermined temperature.

The optical sensor is a selfoc lens 12b at the end of the exposure unit 12 and as an equal-magnification image forming element.
However, it may be provided directly on the light emitting element or between the light emitting element and the non-magnification image forming element. Alternatively, a light guide may be provided in close contact with the same-magnification image-forming element or the light-emitting element to take out light, and an optical sensor may be provided in front of it to measure the amount of light.

Although the above embodiment has been described with respect to the color image forming apparatus, the embodiment of the present invention can be applied to a monochrome image forming apparatus, and can be applied to an exposure unit as an image exposing unit. It is possible to stabilize the emitted light amount by correcting the light amount variation due to temperature change and deterioration of the provided light emitting element.

[0036]

According to the first aspect of the present invention, since the exposure amount at the end portion of the image exposure means provided with a plurality of light emitting elements is detected, an image in which the light amount fluctuation due to the temperature change of the light emitting element is corrected can be obtained.

According to the second aspect, since the fluctuation of the light quantity is corrected for each image exposure means, a color image with a well-balanced color can be obtained.

According to the third aspect, the abnormality of the light emitting element can be detected by the temperature sensor from the relationship between the temperature and the emitted light amount.

According to the fourth aspect, since the image exposing means is provided inside the image forming body, contamination by toner, external dust or the like is prevented.

According to the fifth aspect, the light emitting elements at the end portions are forcibly turned on with the average exposure amount of the plurality of light emitting elements, so that the light emitting amount of the light emitting elements at the end portions is made equal to that of the plurality of light emitting elements. It is possible to maintain the same state, and since the amount of light emitted from the light emitting element is corrected based on the amount of light emitted from the light emitting element at the end portion, it is possible to correct the light amount variation due to deterioration of the light emitting element.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of the image exposure means of FIG.

FIG. 3 is a perspective view of FIG. 2;

FIG. 4 is a diagram showing light amount control of a light emitting element.

[Explanation of symbols]

 10 Photoreceptor Drum 12 Exposure Unit 12a Exposure Element 12b SELFOC Lens 12c Holding Member 20 Fixing Member 121 Light Emitting Element Unit 122 Substrate H1, H2 Heater S1, S2 Optical Sensor T1, T2, T3 Temperature Sensor

Claims (5)

[Claims] 1. An image forming apparatus having an image exposing means in which a plurality of light emitting elements for performing image exposure on an image forming body are linearly arranged, and an exposure amount at an end of the image exposing means is detected. An image forming apparatus comprising an optical sensor, wherein the exposure amount is controlled by the optical sensor. 2. The image forming apparatus comprises a plurality of sets of charging means, image exposing means, and developing means arranged around the image forming body, and the image forming body is rotated during one rotation of the image forming body. On the other hand, the toner image is formed by superposing the toner image on the image forming body by sequentially repeating the formation of the toner image by the charging by the charging unit, the image exposure by the image exposing unit, and the development by the developing unit. The image forming apparatus according to claim 1, wherein the image is collectively transferred to the image forming apparatus. 3. The image forming apparatus according to claim 1, wherein the image exposure unit is provided with a temperature sensor. 4. The image forming apparatus according to claim 1, wherein the image forming body has a cylindrical shape, and the image exposing unit is provided inside the image forming body. apparatus. 5. The image forming apparatus according to claim 1, wherein the light emitting element at the end is forcibly turned on with an average exposure amount of the plurality of light emitting elements.