JPS61153699A - Image former - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an image forming apparatus that forms a display image as a toner image on the surface of a photoreceptor. An image display device that reproduces information or image information stored on magnetic tape or microfilm as a visible image, or an image attached to image forming equipment such as a copying machine or office automation equipment as an image monitor. The present invention relates to a forming device.

[Prior art]

FIG. 1 is a longitudinal sectional side view showing a schematic structure of an example of a conventional image forming apparatus of this type. In FIG. 1, an endless belt-shaped photoreceptor 1, which has a photoconductive layer provided on a transparent and conductive substrate, is placed on rollers 2 and 2' with the transparent substrate on the back side and subjected to an arrow force e. Rotate. On the other hand, the toner 5 having conductivity and magnetism is held on the toner carrier (non-magnetic sleeve) 4 surrounding the magnet 3 by the magnetic force of the magnet 3 and brought into contact with the outer surface of the photoreceptor. When the photoconductive layer is an N-type semiconductor, the substrate side is negative, and when the photoconductive layer is a P-type semiconductor, the substrate side is positive. 4, while applying an electric field due to a direct current voltage between the laser beam 7' and the photoconductive layer 5, the photoconductive layer in the area in contact with the toner 5 is irradiated with optical information through the substrate. Toner adheres to the surface of the photoconductive layer in some areas. Such a process was disclosed in Japanese Patent Application Laid-open No. 58-9.
Publication No. 8748 also discloses this.

To be more specific, the output light beam of the semiconductor laser 7 (
The optical information (corresponding to item -) 7' is scanned in one direction (perpendicular to the plane of the figure) by a scanner 8 such as a galvanometer mirror or a rotating polygon mirror, and passes through an f-theta lens 9 and a mirror 10 to a belt. The back surface of the photoreceptor 1 is exposed to light.

Elements 7.8 and 9.10 are arranged inside the belt l. Note that this exposure means may be an LEII array, a liquid crystal shutter array, or the like.

This photoreceptor l moves in the direction of the arrow, and is made of CdS with resin as a binder on the surface of a transparent polyethylene terephthalate film (this is the base material) which is made conductive by providing a thin film of indium tin oxide on the surface. A photoconductive layer is applied. CdS doped with copper and indium and sensitive to near-infrared light emitted by the semiconductor laser 7 is used. A developing device 12 is provided on the outside of the photoreceptor belt 1, facing the exposure position of the photoreceptor belt 1 that is hit by the laser beam 7'. The developing device is provided with a stationary non-magnetic sleeve 4 having a magnet 3 inside thereof, said magnet 3 rotating in the direction of the arrow.

The conductive and magnetic toner 5 attached to the back surface of the sleeve 4 moves along the surface of the sleeve 4 in the opposite direction to the rotating direction of the magnet 3, is uniformly regulated by the blade 6, and is applied to the photoreceptor l.
surface. The above-mentioned DC voltage is applied between the base of the photoreceptor 1 and the sleeve 4, and the voltage induced on the surface of the photoreceptor differs between the areas hit by the laser beam 7' and the areas not hit by the laser beam 7'. Since there is a large difference in electrostatic attraction between the charge of the toner particles in contact with the charge of the opposite polarity on the photoreceptor side, each part of the surface of the photoreceptor is affected depending on whether the laser beam 7' hits or not. The presence or absence of toner adhesion occurs, and thus development is performed. Since the width of the area where the toner 5 is in contact with the surface of the photoreceptor in the photoreceptor movement direction is much larger than the incident spot of the laser beam 7' on the photoreceptor, the development is completed after exposure with the laser beam 7'. It continues to be carried out even after that. Rollers 11, 11' are provided near the exposure and development positions, which keep the photoreceptor 1 smooth and keep the photoreceptor 1 smooth.
The distance between the surface of the developing device and the sleeve 4 of the developing device is kept constant with high precision.

The toner image formed on the surface of the photoreceptor at a position facing the developing device is sent to the display section 13 by the movement of the photoreceptor, and at this position the movement of the photoreceptor l is temporarily stopped.In the 0 display section, the glass 13' The toner image on the surface of the photoreceptor can be visually observed through the photoreceptor.

The lamps 14 and 15 have the function of making the toner image easier to see by irradiating the surface of the photoreceptor, and of erasing from the photoreceptor the history caused by the electric field received during the image forming process. The lamp 1B is for erasing the history of the photoreceptor, and is turned on only while the belt-shaped photoreceptor 1 is moving, and is turned off when the belt-shaped photoreceptor 1 is stopped.

When changing the displayed content, the photoreceptor 1 is moved again and the photoreceptor with the previously formed toner image on its surface is brought to the same exposure and development process as described above without separately cleaning. At the same time as the previously formed toner image is erased, the next toner image is formed.

It is also possible to provide a white or other thin film having an appropriate resistance on the photoconductor as the photoreceptor.

By using the above-mentioned device, it is possible to display any image by modulating the semiconductor laser 7 with an image electric signal. If it is an electrical signal, it is easy to guide the signal inside the belt.

Image forming apparatuses that display an image by forming the image to be displayed as a toner image on the surface of an image carrier using a photoconductor as described above have a higher resolution than, for example, a CRT display apparatus or a display apparatus using liquid crystal. The advantages are that the image is easy to see and there is little fatigue, and if necessary, it is possible to easily obtain hard copies by adding a mechanism to transfer the toner image formed on the belt surface to the copy paper surface. has.

By the way, in such an image forming apparatus, the image density may fluctuate due to the influence of external light or the like. Therefore, prior to forming a desired image, a means is provided for detecting the current value supplied to the toner and determining the signal light intensity or the DC voltage based on the detection result.

However, since the detected waveform of the detected current value is a current flowing through the conductive and magnetic toner 5 attached to the surface of the non-magnetic sleeve 4 as a medium, it becomes a waveform containing a lot of noise. Therefore, it is necessary to sample the DC component through a filter. Furthermore, in order to sample the current, a sample image (solid black) for forming both sides is formed to sample the current.

Next, we will discuss the timing of conventional current sampling.
This will be explained with reference to the figures. FIG. 2 shows the current waveform after passing through the low-pass filter and its sampling points.

In FIG. 2, if the beginning of sample image formation for long and double formation is set at a point of 1=0, the current increases slowly over one hour as shown in the figure and saturates at a certain constant value. Therefore, the sampling operation is started at a time t1 sufficient for saturation, A/D conversion is performed, for example, three times at a sampling interval t2, and the average value is obtained and used as a control value. For this reason, even if one sampling value changes by one bit due to the influence of disturbance, the probability of erroneous control is extremely high because that value is used.

〔the purpose〕

SUMMARY OF THE INVENTION In view of the above-mentioned points, an object of the present invention is to obtain a target developing bias value prior to forming a desired image.
After sampling the current value supplied to the toner and confirming that the sampled data is stable,
It is an object of the present invention to provide an image forming apparatus in which a target bias value is determined based on this sampling value, thereby preventing erroneous control and forming a stable image.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 3 is a block diagram showing an example of the configuration from current detection to development bias value control of the present invention. Incidentally, since the mechanical configuration of the present invention and the like shown in FIG. 1 can be applied, the explanation thereof will be omitted here.

In FIG. 3, reference numeral 21 denotes a current-voltage converter that detects the current supplied to the toner and converts the current value into a voltage value. supplied to Note that the detection point of the current supplied to the toner may not be one, but may be multiple.The low-pass filter 22 allows only the DC component to pass.

Remove high frequency components. And low pass filter 22
When the output from is input to the A/D converter 23.

The analog value is converted into a digital value and supplied to the control microcomputer 24.

As will be described later, the control microcomputer 24 obtains data by adding up the plurality of digital values when the digital values of the current supplied to the plurality of toners inputted sequentially reach a stable state. Based on the data, predetermined calculations necessary for long-distance formation are performed to determine the developing bias voltage. Thereafter, the control microcomputer 24 outputs digital data to the D/A converter 25 in order to control the developing bias value from the set value to the target value. The analog data output D/A converted by the D/A converter 25 is amplified by the amplifier 2B and applied to the photoreceptor l and the toner carrier (sleeve) as a developing bias voltage.
Supply between 4 and 4.

FIG. 4 shows the timing of current value sampling according to the present invention, and shows that data is sampled between a preset time t3 and a time t4. Note that ao-an in the figure indicates each sampled data.

Next, the control microcomputer 24 shown in FIG.
The calculation will be explained with reference to the flowchart in FIG. Furthermore, this calculation procedure is as follows.

It is assumed that the information is stored in advance in the ROM (ready-only memory) of the microcomputer.

First, after the sample image is formed, sampling is started after a time t3 shown in FIG. In the zero-order step S4, which receives the output of all-1-all=Δa
In step S5 of the first order after calculating n, step S4
It is determined whether the value Δan obtained in step 1 is smaller than the set value α, and if it is smaller, the value of the counter X is increased by "1".

Next, in step S7, it is determined whether the value of Curran Find S using the following formula.

S = an-1+ ajl-1+ am On the other hand, the 4th w
If the value of the counter Let be the value of S mentioned above. Therefore, we obtain S;β.

Once S is determined in this way, in the next step S11, the target developing bias value T is determined using the following equation.

T=aS+b' Here, a and b mentioned above are respective set values,
This is an approximation of the graph (current concentration graph) in FIG. 6 using a -order interval.

In the embodiments, an image is formed on the surface of a belt-shaped photoreceptor using electrophotographic technology, but in the present invention, a latent image is formed on a drum-shaped photoreceptor using light, and development and normal processing are performed. It is also applicable to an image forming apparatus that skips the steps of transferring to paper and fixing.

〔effect〕

As explained above, according to the present invention, when the detected data becomes stable, the target developing bias value is set using the detected data. Erroneous control such as density fluctuation is eliminated, and as a result, a stable image can be formed.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional side view showing a schematic configuration of a conventional device. FIG. 2 is a diagram showing the conventional sampling timing of the current value supplied to toner prior to image formation, and FIG. 3 is a block diagram showing an example of the configuration of the device of the present invention from current detection to development bias value control. , 4g is a diagram showing the sampling timing of the detected current value of the present invention, and FIG. 5 is a flowchart showing an example of the calculation contents of the control microcomputer shown in 3rd ffl. FIG. 6 is a diagram showing an example of the relationship between solid black density and current value. l...Photoreceptor. 4... Toner carrier (sleeve), 21... Current voltage converter. 22...Low pass filter, 23.-A/D converter. 24...control microcomputer, 25.-D/
A converter. 2B--Amplifier. Figure 1 Figure 2 Figure 6 Figure 11 I

Claims (1)

[Scope of Claims] An image forming apparatus that irradiates a photoreceptor with light and causes toner to adhere to the photoreceptor depending on the irradiation state, comprising: a detection unit that detects a value of a current supplied to the toner; determining means for determining whether or not the plurality of current values detected by the detection means are in a stable state; An image forming apparatus comprising: means for determining a target developing bias value based on a current value.