JPS6066273A - Optical printer device - Google Patents

Abstract

PURPOSE:To stabilize the density of a print picture by controlling the quantity of electrification to a photosensitive body so that the measured surface potential of the photosensitive body obtains a prescribed value and coping with the variation of a condition for image formation. CONSTITUTION:A means 4 measures the surface potential of a photosensitive body when the optical image of a light emitting device array 14 is irradiated to the photosensitive body 1 to form the latent image of an origianl picture. A means 24 controls the quantity of electrification to the photosensitive body 1 so that the surface potential of the photosensitive body 1 obtains a prescribed value. Consequently, the ununifomrity of sensitivity characteristics of the photosensitive body 1 is compensated to cope with the variation of the condition for the image formation, and thus, a print picture having stable density is obtained.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to JNOE 1) A method for forming a latent image of an original image by focusing light from a light emitting element array such as a (light emitting diode) array on a photoreceptor. This invention relates to a solid-state scanning type optical printer device.

[Prior art]

Conventionally, as this type of optical printer device, for example, λ-L
An ED array (a large number of fs arranged on an HDi substrate) is used as a light source, and an LMD is used in accordance with the original image to be printed.
A device is known in which a latent image of an original image is formed by emitting light and irradiating the light image onto a photoreceptor.

However, the sensitivity characteristics of photoreceptors vary depending on manufacturing factors, temperature, humidity, and other factors.
The drawback was that it was not possible to obtain print output with an overall stable density.

〔the purpose〕

The present invention was made in order to eliminate the above-mentioned conventional drawbacks, and includes means for measuring the surface potential of a photoreceptor and controlling the amount of electricity applied to the photoreceptor so that the surface potential of the photoreceptor reaches a predetermined value. It is an object of the present invention to provide an optical printer device capable of obtaining a printed image with a low density fc density without regard to the sensitivity characteristics of a photoreceptor.

〔Example〕

Hereinafter, all drawings of an embodiment of the present invention will be described.

FIG. 1 is a block diagram schematically showing an optical printer device according to the present invention. In the figure, 1 is a photosensitive drum that is a drum-shaped photosensitive member, 2 is a printer head for irradiating a light image onto the photosensitive drum 1, and 3 is a charger that uniformly charges the surface of the photosensitive drum 1 by corona discharge. , 4 is a potential sensor as a potential 1111 constant means for measuring the surface potential of the photosensitive drum 1, 5 is a developing device, 6 is a cassette containing transfer paper, 7 is a paper feeding roller, and 8 is a feeding transfer paper metal. 9 is a transfer device that transfers the charged image (electrostatic latent image) on the photosensitive drum 1 to the entire transfer paper; 10 is a fixing roller that fixes the toner attached to the transfer paper, and 11 is a discharge roller; a paper tray; 12 is an eraser for removing electric charge from the photosensitive drum 1;
Reference numeral 13 denotes a cleaner for collecting residual toner 11 on the photosensitive drum 1.

FIG. 2 shows a principle diagram of the light emitting element array that constitutes the printer head 2. As shown in FIG. Here, Ll et al.I)'! are used as light emitting elements. f-I am using this LED array 14
In this case, an electrode 16 and a light emitting section 17 are formed on a substrate 15 made of gallium arsenide (GaAs) or the like which is formed into a plate shape. The light emitting part 17 is formed by semiconductor elements 2PN bonded (fcLEf) 18 through silicon oxide (s12) and arranged in a high density (approximately 16 elements per 1 m+), and the higher the density, the higher the resolution. Become.

FIG. 3 (al, tbi is a control opening diagram and a control circuit diagram for loading all image information to the photosensitive drum 1. In the figure, 19 is 1, 191) each LEpi of the array 14.
a-+.

18-2,...18-nffi driven LE
D driver, 0LED18-, +18-1 respectively
! ,...Transistor Q+, Q2 on 18-n
・・・・・・Qn is resistor R1, R2゜・・・Rn
It is connected via k. El or E.

is the transistor Q+ + Q2 +...Qn
is selected by the selector switch 20, and each L
By changing the current flowing through lli018, EDi
Adjust the amount of light emitted from step 8. A control section 21 controls the LED driver 19, and includes a data selector 22, a memory 23, a high voltage control circuit 24, and the like. Further, the high voltage control circuit 24 charges the photosensitive drum 1 so that the surface potential of the photosensitive drum 1 reaches a predetermined value based on the result of measuring the surface potential of the photosensitive drum 10 with the potential sensor (see FIG. 1). h7. are doing.

Based on the above configuration, the operation will be explained next. Note that since the normal printing operation is well known, detailed explanation will be omitted.

When a print start command is output, the photosensitive drum 1 rotates in the direction of the arrow shown in FIG. 1, and a charger 3 applies a uniform surface charge to the photosensitive drum 1. Next, printer head 2
The light image of the LEDI 8 is irradiated, and an electrostatic latent image corresponding to the original image to be printed is formed. This latent image is visualized by toner being applied by the developing device 5. On the other hand, the transfer paper stored in the cassette 6 is fed by a paper feed roller 7, and is timed by a registration roller 8 so that its leading edge coincides with the leading edge of the image formed on the photosensitive drum 1. will be sent. On this transfer paper,
The toner attached to the photosensitive drum 1 is transferred by a transfer device 9, and the toner is fixed by a fixing roller 10. The print is finally discharged to the L-π feed tray 11, and at the same time, the charge is removed from the photosensitive drum 1 by the eraser 12, and the residual toner is cleaned and collected by the cleaner 13.

Next, the process of irradiating the entire light image of the LED I 8 onto the photosensitive drum 1 will be described.

, the relationship between the light intensity of the light emitting part 17 and the non-light emitting part of the LED array 140 is shown in FIG. When irradiating the photosensitive drum 1 with the light image of the LED I 8, the LED array 14 is brought close to the photosensitive drum 1, or as shown in FIG.
A light image of the LEDI is formed on the photosensitive drum 1 using a focusing rod lens array 25. As a result, a latent image corresponding to the original image is formed on the photosensitive drum 1.

Information on the original image to be printed is once stored in the memory 23 of the control unit 21, and then the transfer speed is converted to a printer writing speed (image writing speed), and the information is input to the data selector 22 as a serial signal. The data selector 22 is
The information of the serial signal is addressed and distributed to the transistor Qt r Q2 of the LED driver 19.
+...The LED array 14 is driven by applying a base current to Qn. At that time, the power supply for the L E I) array 14 is 5fΦ type, and the selector switch 20 is operated by the 1 selection circuit etc. to change the power supply E or E, and change the current flowing to each LED 18. It is possible to control the amount of light emitted. L in Figure 6
E l) Optical output (μW) and forward current (m
Shows the relationship with A). The forward current of LEDl 8 is 10
The voltage value is set so that a forward current of 30, 20, and 10 mA flows through each of the power supplies E1 + E2 + 1, and there is only one power supply. , 14.
The voltage value is set so that even less current flows.

FIG. 7 is a diagram showing how the surface potential of the photosensitive drum 1 changes. The surface potential of the photosensitive drum 1 is first set to V by the charger 3. It is charged to , and then gradually dark decays to ■.
When the light 1-1 of the LED array 14 is irradiated (exposed) after a time of V1. The light attenuates up to At this time, the portions that are not irradiated with the light 1 image do not undergo light attenuation, so a potential difference is generated between the irradiated portions and the non-irradiated portions, and an electrostatic m-image is formed. The process of applying toner to this latent image to make it visible and printing it on transfer paper is as described above.

Note that Vs shown in FIG. 7 indicates the saturation value of the potential charged on the photosensitive drum 1.

In general, the relationship between the amount of irradiated light and the development density, so-called γ characteristics, does not have a constant linear characteristic depending on the temperature, humidity, and other conditions of the photoreceptor itself. Also, LED
The amount of light emitted from the light source 18 itself fluctuates due to heat, and the wavelength of light emitted may also shift. Therefore, a potential sensor 4 is provided to measure the surface potential of the photosensitive drum 1. First, standard mist lighting is performed by lighting the LED IFl so that a predetermined amount of light is emitted, and the surface potential at this time is determined by 4111.
If the predetermined surface potential cannot be obtained, the high voltage control circuit 24
As a result, the amount of high-voltage charge applied to the photosensitive drum 1 is changed, and potential measurement and adjustment of the amount of charge are repeated so that the surface potential is within a predetermined range. In this way, changes in the γ characteristics can be accommodated.

Adjust the high-voltage charging it'+- to the above photosensitive drum 1'
A specific example of controlling the torso position will be explained with reference to the flowchart in FIG.
It is controlled by the phycrocomputer of D24-1.

In FIG. 9, 3 and 24 are an embodiment of the pressure control circuit. 2'4-1 is a microcomputer f, 1b. 24-2 is a D/A converter that converts the digital signal commanded by the microcomputer into an analog signal, 24-3 is a voltage follower circuit, and 24-4 is an appeasing amplifier circuit, which is connected to the charger 3. A constant current circuit is realized by feeding back the flowing current.

24-5 is an oscillator 1, and a step-up transformer 24-6
High pressure is obtained by combining with

24-7 is a high voltage rectifier circuit which converts the switching waveform into full direct current and supplies it to the charger 3.

First, in step 101, a standard non-lighting power supply of 1 l;
Adjust the amount of light emitted by the LEDI. This power supply E3 is a standard L
This is a power source that can obtain the amount of light emitted by the ED 18, and all voltage values are normally set so that VL is obtained as the surface potential.

Next, in step 102, when the standard exposure ends and the potential measurement timing comes, the surface potential is measured. and,
In step 103, the measured potential is compared with a predetermined reference potential (VL).

That is, if the measured potential is higher than the reference potential, as shown in FIG. 7, the optical attenuation is insufficient. this is,
If the amount of light emitted from the LED 18 cannot be adjusted because the amount of light emitted by the LEI) 18 is small or the amount of charge is too large, the amount of high-voltage charge is controlled to be reduced, and the potential measurement from the bow degree step 102 is performed. Do everything. If the measured potential matches the reference potential, the potential control ends; if they do not match, the high-voltage charge amount is reduced and the potential is measured. repeat.

On the other hand, if the measured potential is lower than the reference potential, either the amount of high-voltage charge is small or the amount of light emitted from the LED 18 is too large, so the high-voltage charge is controlled to be increased and the potential measurement is repeated.

By controlling the VRC potential in this manner, it is possible to correct the non-uniformity of the sensitivity characteristics of the photosensitive drum 1 and to obtain a stable entire printed image at one time.

〔effect〕

As described above, according to the present invention, in an optical printer device in which light 1# of a light emitting element array is irradiated onto all photoconductors to form a full latent image of an original image, the surface potential of the photoconductor is measured. Since the fc configuration is equipped with means for fully controlling the amount of charge on the photoreceptor so that the surface potential of the photoreceptor becomes a predetermined value, it is possible to correct non-uniformity in the sensitive characteristics of the photoreceptor, and therefore to improve image formation. This has the effect of being able to respond to changes in the conditions and producing printed images with stable density.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the outline of an optical printer device according to the present invention, Fig. 2 is a principle diagram of a light emitting element array, and Fig. 3 is a fal
, (bl is a control block diagram and control circuit diagram for writing all image information to the photosensitive drum, Figure 4 is a diagram showing the relationship between the light intensity of the light emitting part and the non-light emitting part of the LED array, and Figure 5 is the control circuit diagram for writing all image information on the photosensitive drum. L on the photosensitive drum using a rod lens array.
FIG. 6 is a diagram showing the relationship between the light output of the LED and the current in the l1li direction. FIG. 7 is a diagram showing how the surface potential of the photosensitive drum changes. The figure is a flowchart showing a specific example of potential control, and Figure 9 is a flowchart showing a specific example of potential control.
This is a diagram showing an example of a high voltage control circuit including a microcomputer that controls the flowchart shown in the figure. 1......Photosensitive drum 3...Charger 14...I, ED array 18...Ll et al.D 24... ...High voltage control circuit Figure 4 Figure 5 Figure 6 Figure 7

Claims (1)

[Claims] In an optical printer device in which a photoreceptor is irradiated with a light image of a light emitting element array to form a latent image of an original image, there is provided a means for measuring a surface potential of the photoreceptor; 1. An optical printer device comprising: means for controlling charging sensitivity to a photoreceptor so that the photoreceptor is charged sensitively.