JPH11157126A - Image forming method and equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize remarkably higher image quality than that in conventional methods. SOLUTION: The image forming equipment is furnished with a photoconductive electrostatic latent image holding member 21 and an electrostatic latent image forming means that forms an electrostatic lenient image corresponding to image information by laser beams produced from laser light sources 50a, 50b and has a latent image potential detection means 24 that detects the potential of the electrostatic latent image, and a laser output adjustment means 29 that adjusts the output levels of the laser light sources 50a, 50b so that the results of detection of the latent image potential detection means 24 for the electrostatic latent image formed by the laser light sources 50a, 50b may match the defined potential of a latent image. As the equipment can thus adjust the output levels of the laser light sources 50a, 50b, including factors contributing to errors, such as manufacturing irregularities in an optical system in an optical path and the electrostatic latent image holding member 21 and characteristics deterioration due to secular changes, the equipment can realize stable high image quality free from irregularities between the laser light sources and those due to secular changes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming method and an image forming apparatus using an electrophotographic process, such as a copying machine, a facsimile, and a printer.

[0002]

2. Description of the Related Art In an electrophotographic image forming apparatus, an electrostatic latent image holding member having photoconductive properties is charged and exposed to form an electrostatic latent image, and a developing member having a fixed charge amount is electrostatically charged on the electrostatic latent image. This is a device that makes a visible image by attaching it by force.
In recent years, with the development of office amenities and the spread of personal computers, the market for electrophotographic image forming apparatuses
It is expanding and matured, and it is expected that higher speed and higher image quality will be required in the future.

A conventional electrophotographic image forming apparatus will be described below with reference to the drawings. FIG. 6 is a sectional view schematically showing a conventional electrophotographic image forming apparatus, and FIG. 7 is a conceptual diagram for explaining an electrostatic latent image forming means having a plurality of laser light sources. As shown in FIG. 6, a conventional electrophotographic image forming apparatus includes a charging unit 22, an electrostatic latent image forming unit 23, and a developing unit around a photoconductive electrostatic latent image holding member 21 arranged substantially at the center. A unit 25, a transfer unit 26, a fixing unit 27, and a cleaning unit 28 are provided. The photoconductive electrostatic latent image holding member 21 is uniformly charged in a dark place by the charging unit 22, and the electrostatic latent image forming unit 2
3 forms an electrostatic latent image 41 corresponding to the image information, the developing unit 25 forms a developing member image 42 according to the potential of the electrostatic latent image 41, and the transfer unit 26 forms the electrostatic latent image holding member 21. The attached developing member image 42 is
5, a developing member image 43 adhered to the sheet 35 is formed, the developing member 32 is fixed by the fixing unit 27, and a sheet image 44 is formed.
Accordingly, the charge is removed and the remaining developing member is removed so that the electrostatic latent image holding member 21 can be reused. Image formation is continuously performed according to the above process procedure.

Next, the electrostatic latent image forming means 23 will be described with reference to FIG. Laser beams generated from the plurality of laser light sources 50a and 50b pass through the collimator lenses 51a and 51b, the laser beam combiner 52, the polygon mirror 53, and the fθ lens 54, and travel on the electrostatic latent image holding member 21 in the main scanning direction (Ms).
Direction). Conventionally, with respect to variations in the output level of the laser light source, the light levels of the laser light sources 50a and 50b are detected and fed back to the laser drive circuits 55a and 55b, so that the output level of the laser light source becomes a specified value. Has been adjusted.

[0005]

However, when the means for adjusting the output level of the laser light source as described above is applied to an image forming apparatus using a plurality of laser light sources 50a and 50b, the light intensity of each of the laser light sources 50a and 50b is increased. Is adjusted to a specified value, there is an optical system such as collimator lenses 51a and 51b in the optical path from the laser light sources 50a and 50b to the electrostatic latent image holding member 21. The output level of the laser beam on the surface 21 is not always a specified value. Further, even if the output of the laser light sources 50a and 50b is adjusted to a specified value due to manufacturing variations of the electrostatic latent image holding member 21 and deterioration of the photoconductive characteristics due to aging of the electrostatic latent image holding member 21, the electrostatic force may be reduced. The latent image potential formed on the latent image holding member 21 is not always the specified potential. For this reason, the formed image is not uniform, and there is a problem that image defects are likely to occur.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an image forming method and an image forming apparatus capable of realizing much higher image quality than conventional methods in view of the above-mentioned problems.

[0007]

According to the present invention, there is provided an image forming method for forming an electrostatic latent image corresponding to image information on an electrostatic latent image holding member by a laser beam generated from a laser light source. A latent image potential of an electrostatic latent image formed by the laser light source is detected, and an output level of the laser light source is adjusted so that the latent image potential matches a specified latent image potential.

As described above, the latent image potential of the electrostatic latent image formed by the laser light source is detected, and the output level of the laser light source is adjusted so that the latent image potential matches the specified latent image potential. The latent image potential formed on the latent image holding member always becomes the specified latent image potential, and even if there are error factors such as manufacturing variations of the optical system and the electrostatic latent image holding member in the optical path and deterioration of characteristics due to aging, the variation is caused. It is possible to realize stable and high image quality without noise.

According to a second aspect of the present invention, there is provided an image forming apparatus, comprising: an electrostatic latent image holding member having photoconductivity; and an electrostatic latent image corresponding to image information on the electrostatic latent image holding member by a laser beam generated from a laser light source. An electrostatic latent image forming means for forming an electrostatic latent image, comprising: a latent image potential detecting means for detecting a potential of the electrostatic latent image; and a latent image potential detecting means for detecting an electrostatic latent image formed by a laser light source. And a laser output adjusting means for adjusting the output level of the laser light source so that the detection result obtained by the means matches the specified latent image potential.

As described above, the laser light source is operated by the electrostatic latent image forming means to form an electrostatic latent image on the electrostatic latent image holding member, and the detection result by the latent image potential detecting means matches the specified latent image potential. By adjusting the output level of the laser light source by the laser output adjusting means as described above, the optical system in the optical path, manufacturing variations of the electrostatic latent image holding member, including error factors such as characteristic deterioration due to aging, and the like, Since the output level can be adjusted, it is possible to realize stable high image quality without variation between laser light sources and aging.

According to the third aspect of the present invention, there is provided the image forming apparatus according to the second aspect.
, The laser output adjusting means has a laser spot diameter adjusting means for adjusting the spot diameter of the laser light source in accordance with the detection result by the latent image potential detecting means. As described above, the laser output adjusting means has the laser spot diameter adjusting means for adjusting the spot diameter of the laser light source in accordance with the detection result by the latent image potential detecting means. The output level can be adjusted.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a sectional view schematically showing an image forming apparatus according to an embodiment of the present invention, and shows only a structure deeply related to image formation of a digital copying machine as an embodiment. FIG. 2 is a conceptual diagram for explaining the electrostatic latent image forming means of the first embodiment, and FIG. 3 is a flowchart showing an operation for adjusting the output level of the laser light source. In FIG. 1, a digital copying machine according to this embodiment includes a charging unit 22 and an electrostatic latent image forming unit 2 around a photoconductive electrostatic latent image holding member 21 disposed substantially at the center.
3, a latent image potential detecting unit 24, a developing unit 25, a transfer unit 26, a fixing unit 27, a cleaning unit 28, and a laser output adjusting unit 29. 2, the electrostatic latent image forming unit 23 includes a plurality of laser light sources 50.
a, 50b, collimator lenses 51a, 51b, laser beam synthesizer 52, polygon mirror 53, fθ lens 5
4 is provided. The laser output adjusting means 29 includes laser driving circuits 55a and 55b, laser light source controlling means 56, CP
U57 is provided.

The photoconductive electrostatic latent image holding member 21 is uniformly charged in a dark place by the charging unit 22, and a light energy distribution 40 corresponding to image information is performed by the electrostatic latent image forming means 23. An electrostatic latent image 41 is formed. The developing unit 25 has a sleeve 34, and supplies the developing member 32 and the carrier 33. The developing unit 25 forms a developing member image 42 in accordance with the potential of the electrostatic latent image 41, and the transfer unit 26 transfers the developing member image 42 attached to the electrostatic latent image holding member 21
Is formed, the developing unit 32 is fixed by the fixing unit 27 to form a sheet image 44, and the cleaning unit 28 removes and removes the electrostatic latent image holding member 21 so that the electrostatic latent image holding member 21 can be reused. The developing member 32 is removed. Image formation is continuously performed according to the above process procedure.

The electrostatic latent image forming means 23 forms the electrostatic latent image 41 on the electrostatic latent image holding member 21 by laser beams generated from the plurality of laser light sources 50a and 50b. A certain laser output adjusting means 29 is included. The laser beam 31 is transmitted through a collimator lens 51.
a, 51b, the laser beam synthesizer 52, the polygon mirror 53, and the fθ lens 54, and the electrostatic latent image holding member 21 is scanned in the main scanning direction (Ms direction).

The laser output adjusting means 29 controls the laser driving circuits 55a and 55b in accordance with a command from the CPU 57 to adjust the output levels of the laser light sources 50a and 50b. In this case, image information for adjusting the output level of the laser light sources 50a and 50b and a signal indicating the output level of each of the laser light sources 50a and 50b are output from the CPU 57 to the laser light source control means 56. The laser light source control means 56 controls the output of each laser light source 50a, 50b, and outputs a control signal to each laser drive circuit 55a, 55b. As a result, a laser beam having an output level corresponding to the signal is generated by the laser light sources 50a and 50b.

The operation of adjusting the output levels of the laser light sources 50a and 50b will be described with reference to FIG. First, a specified latent image potential as a target of the latent image potential, for example, -100 V is input assuming negative charging (step 61), and a laser light source to be adjusted first, for example, a laser light source 50a is selected (step 62). ), An initial value, for example, 0.1 mW is given to the output level of the laser light source 50a (step 63).
Next, only the selected laser light source 50a is driven (step 64), and the electrostatic latent image holding member 21 is scanned on the basis of the image information for adjusting the output level of the laser light source 50a to form the electrostatic latent image 41. (Step 65). The potential of the electrostatic latent image 41 is, for example, a latent image potential
Is detected as -200 V (step 67), and C
It is input to PU57. The detected latent image potential is compared with the specified latent image potential (step 68).
The PU 57 issues a command to change the output level of the laser light source 50a (step 71). For example, the laser light source 50
a output level 0.1 mW, detected latent image potential −200
V, the specified latent image potential is -100 V, the CPU 57 issues a command to increase the output level of the laser light source, for example, a command of 0.2 mW. Only the laser light source 50a is driven by the laser light source control means 56 and the laser drive circuit 55a to form the electrostatic latent image 41 again, and the potential of the latent image is detected. Until the latent image potential of the laser light source 50a matches the specified potential, the latent image potential is formed and detected, and the output level of the laser light source 50a is adjusted. When the adjustment of the output level of the laser light source 50a is completed (step 69), the next laser light source is selected (step 72).
b, and similarly gives an initial value to the output level of the laser light source 50b, drives only the selected laser light source 50b, and forms and detects the latent image potential until the detected latent image potential matches the specified latent image potential. Then, the output level of the laser light source 50b is adjusted. This operation is repeated by the number of laser light sources, and the output levels of the laser light sources 50a and 50b are adjusted and determined (step 70).

As described above, for example, when the laser light source is a semiconductor laser, each of the laser light sources 50a and 50b is operated independently by the electrostatic latent image forming means 23 and the electrostatic latent image is held on the electrostatic latent image holding member 21. 41, and the laser light sources 50a, 50b
By means of the laser output adjusting means 29, the laser light sources 50a, 5a are controlled so that the potential of the electrostatic latent image 41 formed by
By adjusting the output level of 0b, the optical system in the optical path,
Since the output level of the laser light source is adjusted including error factors such as manufacturing variations of the electrostatic latent image holding member 21 and characteristic deterioration due to aging, stable high image quality without variation between the laser light sources and aging. Can be realized.

A second embodiment of the present invention will be described with reference to FIGS. FIG. 4 is an explanatory view for explaining an electrostatic latent image forming means of the image forming apparatus according to the second embodiment of the present invention, and FIG. 5 is an explanatory view of a slit operation showing an operation of a slit. The outline of this image forming apparatus is the same as FIG. 1 shown in the first embodiment, and the image forming procedure is the same as FIG. 3 shown in the first embodiment. 29, the slits 58a, 58b,
Slit driving circuits 59a and 59b and laser spot diameter control means 60 are provided.

The laser spot diameter control means 60 has a CPU
Each slit drive circuit 59a, 59
b is controlled to control the slit width. The CPU 57 outputs image information for adjusting the laser light source and a signal indicating the spot diameter level of each laser light source to the laser spot diameter control means 60. The laser spot diameter control means 60 controls the slit width of each of the laser light sources 50a and 50b, and outputs a control signal to each of the slit drive circuits 59a and 59b. The slit width corresponding to the signal is determined by slits 58a and 58b.
Is realized by:

Next, the operation of the slits 58a and 58b will be described with reference to FIG. Slits 58a, 58b
The aperture ratio changes when the transmittance of the laser beam partially changes due to an electric signal. For example, as shown in FIG. 5, the liquid crystal device is configured by an electro-optical element,
The aperture ratio of the slit 58 changes depending on the ratio of the laser beam transmitting portion A and the laser beam non-transmitting portion B. When the aperture ratio of the slit 58 is large as shown in FIG. 5A, the laser beam transmitting portion A of the electro-optical element becomes wide and the slit width becomes large. When the aperture ratio of the slit 58 is small as shown in FIG. 5B, the laser beam transmitting portion A of the electro-optical element becomes narrow and the slit width becomes small. As described in the first embodiment, the slit width is adjusted by driving only the single laser light source and adjusting the electrostatic latent image holding member 2.
1, a latent image potential is formed and detected until the latent image potential detected by the latent image potential detecting means 24 matches the specified latent image potential, the slit width is adjusted, and the laser spot diameter is adjusted. To adjust. This operation is repeated by the number of laser light sources, and the respective slits 58a and 58b are adjusted to determine each laser spot diameter.

As described above, the laser light sources 50a and 50b are independently operated by the electrostatic latent image forming means 23 to form the electrostatic latent image 41 on the electrostatic latent image holding member 21, and the latent image potential detecting means 24 From the detection results by the laser light sources 50a,
The laser output adjusting means 29 adjusts the slit 58 so that the potential of the electrostatic latent image 41 formed by the
By adjusting the laser spot diameter by adjusting a and 58b, the laser spot diameter can be adjusted including error factors such as manufacturing variations of the optical system in the optical path and the electrostatic latent image holding member 21 and characteristic deterioration due to aging. As a result, stable and high-quality images can be realized without variation among the laser light sources due to aging.

In the above embodiment, an example is described in which the output level of the laser light source or the laser spot diameter is adjusted so that the potential of the latent image formed by the image forming means including two laser light sources becomes uniform. As described above, an image forming apparatus including one or three or more laser light sources can be similarly applied to the adjustment of the output level or the laser spot diameter of each laser light source.

In the above embodiment, the case where the electrostatic latent image holding member is negatively charged by the charging unit has been described as an example. However, the present invention can also be applied to an image forming apparatus in the case of positively charging.
Further, in the above embodiment, a digital copying machine has been described as an example, but the present invention is not limited to this, and can be applied to an image forming apparatus using an electrophotographic process, such as a laser printer.

[0024]

According to the image forming method of the present invention, the latent image potential of the electrostatic latent image formed by the laser light source is detected, and the output of the laser light source is adjusted so that the latent image potential matches the specified latent image potential. Since the level is adjusted, the latent image potential formed on the electrostatic latent image holding member always becomes the specified latent image potential, and the optical system in the optical path, manufacturing variations of the electrostatic latent image holding member, deterioration of characteristics due to aging, etc. Even if there is an error factor, it is possible to realize stable and high image quality without variation.

According to the image forming apparatus of the present invention, the laser light source is operated by the electrostatic latent image forming means to form an electrostatic latent image on the electrostatic latent image holding member, and the detection result by the latent image potential detecting means is defined. By adjusting the output level of the laser light source by the laser output adjusting means so as to match the latent image potential,
It is possible to adjust the output level of the laser light sources, including error factors such as manufacturing variations of the optical system in the optical path and the electrostatic latent image holding member, and characteristic deterioration due to aging. It is possible to realize stable high image quality without variation.

According to a third aspect of the present invention, the laser output adjusting means has a laser spot diameter adjusting means for adjusting the spot diameter of the laser light source in accordance with the detection result by the latent image potential detecting means. Thus, the output level of the laser light source can be adjusted.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating an electrostatic latent image forming unit according to the first embodiment of the present invention.

FIG. 3 is a flowchart illustrating an operation of adjusting an output level in the embodiment of the present invention.

FIG. 4 is an explanatory diagram illustrating an electrostatic latent image forming unit according to a second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing an operation of a slit in the second embodiment of the present invention.

FIG. 6 is a cross-sectional view schematically illustrating a conventional image forming apparatus.

FIG. 7 is an explanatory diagram illustrating a conventional electrostatic latent image forming unit.

[Explanation of symbols]

 Reference Signs List 21 electrostatic latent image holding member 22 charging unit 23 electrostatic latent image forming means 24 latent image potential detecting means 25 developing unit 26 transfer unit 27 fixing unit 28 cleaning unit 29 laser output adjusting means 30 electric charge 31 from electrostatic latent image forming means Generated laser beam 32 Developing member 33 Carrier 34 Sleeve 35 Paper 40 Light energy distribution 41 Electrostatic latent image 42 Developing member image 43 Developing member image 44 Paper image 50a, 50b Laser light source 51a, 51b Collimator lens 52 Laser beam synthesizer 53 Polygon Mirror 54 fθ lens 55a, 55b laser drive circuit 56 laser light source control means 57 CPU 58a, 58b slit 59a, 59b slit drive circuit

Claims (3)

[Claims] 1. An image forming method for forming an electrostatic latent image corresponding to image information on an electrostatic latent image holding member by a laser beam generated from a laser light source, wherein the electrostatic latent image is formed by the laser light source. Wherein the latent image potential is detected and the output level of the laser light source is adjusted so that the latent image potential coincides with the specified latent image potential. 2. An electrostatic latent image holding member having photoconductivity,
An electrostatic latent image forming means for forming an electrostatic latent image corresponding to image information on the electrostatic latent image holding member by a laser beam generated from a laser light source,
A latent image potential detecting means for detecting the potential of the electrostatic latent image; and the laser light source such that a detection result of the electrostatic latent image formed by the laser light source by the latent image potential detecting means coincides with a specified latent image potential. And a laser output adjusting means for adjusting the output level of the image forming apparatus. 3. The laser output adjusting means has a laser spot diameter adjusting means for adjusting a spot diameter of a laser light source in accordance with a detection result by the latent image potential detecting means.
The image forming apparatus as described in the above.