JPS6157977A - Image forming device - Google Patents

Abstract

PURPOSE:To reduce the power loss and to make elements and a radiator small- sized by performing turn-on/off binary control of an exposure means for optical destaticization of an image forming device and controlling the quatity of light with this turn-on/off time ratio. CONSTITUTION: In case of a copying machine of process type, a drum-shaped photosensitive body 11 is electrified uniformly by an electrifier 12 and is exposed with a reflected light 13 from an original to form a latent image, and this latent image is developed by a developing device 15. meanwhile, a copy paper (recording paper) 18 is carried and controlled so that it coincides with this developed image in a transfer position, and the developed image is transferred to the paper 18 by a transfer charger 16, and the paper 18 is destaticized by an electrifier 17 and is peeled. A blank exposure lamp 14 which prevents a toner from sticking non-image areas on the photosensitive body 11 consists of plural LEDs arranged in the axial direction of the drm, and LEDs are lit selectively in accordance with the copy magnification. The process speed of this copying machine is switched in accordance with the copy magnification.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to an image forming apparatus that performs optical charge removal.

[Prior art]

In a conventional image forming apparatus 1, such as an electrophotographic (electrostatic) copying machine, two types of systems have been used to make the copying magnification variable. That is, (1) process (processing)
A method that keeps the speed constant and changes the scanning speed of the document.
Or, (2) a method of varying the process speed and the scanning speed of the document. However, in the method of (1) above, in which the process speed is constant and the scanning speed of the document is variable, since the process speed is constant, The amount of light for optical static elimination in the blank exposure on the photoreceptor surface that is performed simultaneously with the negative corona discharge of the next charger may be constant, and the ON-OF
Since only F is controlled, the configuration of the optical static eliminator can be simplified, but on the other hand, the copying machine itself must be made smaller in order to adapt the entire device to the maximum scanning speed of the original. It was difficult.

In addition, in the method (2) in which the process speed and document scanning speed are made variable, a circuit for controlling the voltage applied to the light source is required in order to make the amount of light for optical static elimination correspond to the process speed, and Since power loss occurs in this voltage control circuit, there are problems with miniaturization, such as the need for a control element, a radiator, etc. with sufficient capacity.

〔the purpose〕

The present invention has been made in view of the above-mentioned problems, and its purpose is to efficiently perform light control of photostatic charge removal to reduce power loss and to enable miniaturization. .

〔Example〕

In this example, the control element that applies voltage to the light source for optical static elimination is operated with two values, ON and OFF.
-OF F A method of controlling the amount of light by changing the time ratio is used to saturate the control element, and by reducing the power loss consumed by the control element, the element itself and the heat sink for it are miniaturized. It is configured as follows.

Examples of the present invention will be described below.

FIG. 1 shows a schematic configuration example of the main parts of a Carlson process type copying machine to which the present invention is applied. Photoreceptor 11 on the drum
After being uniformly charged by the charger 12, it is exposed to reflected light 313 from an original (not shown) to form a latent image, and the latent image is developed by the developer 15.

On the other hand, the copy paper (recording paper) 18 is conveyed under control so that the developed image coincides with the transfer position.

After being transferred by the transfer charger 16, the charge is removed by the charger 17 and the film is peeled off. 14 is a blank exposure lamp that prevents toner from adhering to the non-image area on the photoreceptor 11, and has a configuration in which a plurality of LEDs are arranged in the axial direction of the drum, and the LEDs are selected according to the copying magnification. lights up.

Note that the process speed of this copying machine is configured to be switched depending on the copying magnification.

Figure 2 shows the light amount control circuit diagram of the blank exposure lamp 14.
Piece 5. FIG. 3 is a flow chart thereof. In FIG. 2, 3 is one of the LEDs constituting the blank exposure lamp 14, 1 is a controller CPU for controlling the lighting/extinguishing timing of the light source Ll 13D3, and 2 is a CPU
1 is a transistor for supplying current to the light source LED 3 according to a signal, 4 is a resistor that determines the current flowing to the LED 3, and 5 is a resistor for interfacing between the CPU 1 and the transistor 2.

Next, the operation will be explained according to the flowchart of FIG.

In the CPU 1, when the process shown in step 1 is executed, if the timing to execute the blank exposure process has been reached (YES), the process proceeds to step 4. If it is not the timing to execute the blank exposure process (No), the process proceeds to step 2.

In step 2, data is output to the CPUI port so that the blank exposure light source LED 3 is turned off, and the process proceeds to step 3.

In step 3, the operation of a timer (not shown) in the CPU that controls the turn-off/light-on time of the LED 3 is stopped, and the process proceeds to step 10, where the blank exposure control process is ended.

In step 4, it is determined whether or not the timer of the CPU 1, which manages the lighting/extinguishing time of blank exposure, has expired. If the timer has expired, proceed to step 5. If the timer has not expired, step 10
Then, the process of blank exposure: b'IN is completed.

In step 52, it is determined whether the blank exposure LED 3 should be turned on or off. If the light is turned on, proceed to step 6; if the light is turned off, proceed to step 8.

In step 6, a timer for the LED 3 to be lit is set in the timer of the CPU 1, and the timer operation is started, and the process proceeds to step 7.

In step 7, set the CP so that LED3 lights up.
The boat U1 is set and the process proceeds to step 10, ending the downward rank exposure control process.

In step 8, the time for which the LED'3 is turned off is calculated from the process speed, and the calculated time is set in the timer of the CPU 1 to start the timer operation, and the process proceeds to step 9.

In step 9, set the CP so that LED3 lights up.
The boat U1 is set and the process proceeds to step 10, where the blank exposure control processing is completed.

In the above embodiments, the light amount control of the blank exposure lamp has been described, but exactly the same control can be performed for pre-exposure, post-exposure, etc. in the image forming process.

〔effect〕

As explained above, according to this invention.

Turn on and off the exposure means for photostatic charge removal of the image forming device.
Since the light amount is controlled by the ON-OF'F time ratio by performing binary control of It has become possible.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of a copying machine to which the present invention is applied;
FIG. 2 is a diagram showing an example of a light amount control circuit for blank exposure according to the present invention, and FIG. 3 is a flowchart thereof. 1......Controller CPU3...
...Light source LED JP-A-Sho Gl-57977 (3) Figure 1 Figure 2

Claims (1)

[Claims] comprising an exposure means for removing charges on the photoreceptor with light, and a control means for controlling ON-OFF time of the exposure means,
An image forming apparatus characterized in that the light amount of the exposure means is controlled by the ON-OFF time ratio.