JPH0227367A - Electrostatic recorder - Google Patents

Abstract

PURPOSE:To prevent dewing and deterioration of a characteristic of a material by switching electrically a heater provided in the vicinity of the lower part of a photosensitive drum and a motor to each other by the same relay for controlling them. CONSTITUTION:By switching a heater 2 and a motor 3 by the same relay 12, the heater 2 is not heated when the motor 3 is driven, and the heater 2 is heated when the motor 3 is stopped, therefore, in a time part of T1 being in an operating state by synthetic heat of a heat source, etc. of a fixing device and in a time part of T1' being in a holding state immediately after the operating state, it does not occur that the temperature of a device rises suddenly, and deterioration caused by a temperature of a material can be prevented.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to control of a drive motor and a heater in an electrostatic recording device such as a copying device using a general electrophotographic method.

[Conventional technology]

In a typical copying machine, an original image placed on a document table is rotated by an optical system on a uniformly charged photoreceptor drum surface.
After this is projected and an electrostatic latent image is formed, the toner image is developed with toner (developer) and transferred to recording paper that is conveyed in synchronization. After being separated from the photoreceptor drum, it is fixed by heat. An image copy is formed and transported out of the device. - The residual toner after transfer on the photosensitive drum is removed by a cleaner in preparation for the next copy image formation. All of these series of image forming operations are performed in synchronization with the rotation of the photoreceptor drum, and are configured to operate continuously. Furthermore, near the bottom of this photoreceptor drum in the copying machine,
In order to prevent dew condensation on the photoreceptor drum and the like when used in a low or high temperature environment, a heater with a relatively small heat capacity is installed. In many cases, this heater is configured so that it is always energized and self-temperature controlled as long as the power source is connected. If water droplets adhere to the surface of the photoreceptor, it will not be possible to form an image, so the heater temperature should be high to prevent condensation, but photoreceptor drums are generally sensitive to heat.
Also, since the toner collected in the cleaner has the property of agglomerating at temperatures above 50 degrees Celsius, the heater temperature cannot be raised to an extreme level, and the heater temperature should be set at an intermediate point between the temperature at which condensation occurs and the temperature at which the properties of the material deteriorate. Currently, it is necessary to set the temperature. In addition, although a copying machine is equipped with a heater, it also has a heat-generating part such as a fuser, and when continuous copying is performed, the inside of the machine becomes hot, so a cooling fan is installed to cool the generated hot air. From the standpoint of noise countermeasures, some cooling fans that exhaust air outside the apparatus are controlled so that the air volume is increased during copying operations and reduced during standby.

[Problems to be solved by the invention]

As described above, in conventional devices, the heater temperature must be set at a midpoint between dew condensation and material property deterioration. Furthermore, when the drive motor of the device is activated and the photoreceptor drum rotates to begin a series of copying operations, the transfer paper passes through a fixing device and is ejected from the device, but this fixing device is kept at a constant high temperature. The total amount of heat generated increases and the entire device is heated. The photoreceptor drum and the cleaner receive heat from both the anti-condensation heater and the fixing device, which accelerates the temperature rise and poses a risk of deteriorating the properties of the material. Furthermore, although the cooling fan works to prevent this risk, its air volume decreases during standby immediately after the copying operation is completed, so there is a risk of overheating due to the constantly energized heater. SUMMARY OF THE INVENTION An object of the present invention is to provide an electrostatic recording device that prevents dew condensation inside the device and is controlled so that the temperature inside the device does not rise to an appropriate temperature and the characteristics of the material deteriorate.

[Means to solve the problem]

To achieve the above object, the present invention is characterized in that the heaters, which are driven and rotated by a motor and are provided near the bottom of a photosensitive drum that performs image formation, are electrically switched and controlled by the same relay as the motor. Accomplished by electrostatic recording devices.

【Example】

FIG. 1 is a configuration diagram showing an example of an electrostatic recording device using an electrophotographic method, FIG. 2 is a wiring diagram of an electric circuit of the present invention, and FIGS. 3 and 4 are a cleaner and a photosensitive drum portion according to the present invention. FIG. The present invention will be explained below using a copying machine as an example. As already mentioned, in the normal copying apparatus shown in FIG. After the image is formed, the toner image is developed with toner (developer) and transferred onto a recording paper 9 that is conveyed synchronously. After being separated from the photosensitive drum 1, it is heated and fixed in a fixing device 4 to make an image copy. is forming. On the other hand, the residual toner on the photosensitive drum 1 is removed by the cleaner unit 6 in preparation for the next copy image formation. All of these series of copy operations are driven by the main drive motor 3, and the copy sequence is configured to be performed continuously in synchronization with the rotation of the photosensitive drum driven by the drive motor 3. Furthermore, a heater 2 is installed near the bottom of the photoreceptor drum 1 to prevent dew condensation on the photoreceptor drum, etc., and a cooling fan 5 is also installed. Normally, when the copying machine is turned on, it is in a standby state (idling), and when the copy button (manual switch) is pressed, the control unit drives the drive motor 3 mentioned above and enters the copy operation state (copy screen fence). . In FIG. 2, one end of the power source 11 is connected to the C terminal of the relay 12, and the other end is connected to the heater 2 and the drive motor 3. Also, the other terminals of heater 2 and drive motor 3 are connected to relay 1, respectively.
It is connected to the A terminal and B terminal of 2. When the power cord of the device is connected or the power switch is turned on and the device is in standby mode, relay 1 is activated as shown in Figure 2.
The C terminal of the heater 2 is connected to the A terminal, and the heater 2 is heated under constant temperature control. The time portion of Tl in FIG. 3 corresponds to this. Next, when the copy button is pressed to enter the operating state, the relay 12 is activated, the connection of the C terminal is switched from the A terminal to the B terminal, heater heating is interrupted, and the drive motor 3 is driven to continue the series of operations. This corresponds to the time T2 in FIG. 3 in which the connection state of the relay 12 to the B terminal is maintained during operation under the control of a control unit such as a microcomputer. When the operation is completed, the relay 12 is connected to the C terminal again, the drive motor 3 stops, heats the heater 2, and enters a standby state, which corresponds to the time period T2'. By switching heater 2 and motor 3 using the same relay in this way, the heater does not heat up when the motor is driving, and the heater is always energized and heated when the motor is stopped. The temperature of the equipment does not rise rapidly during the time period Tl when it is in the operating state due to the integrated heat of the heat source, and during the time period TI' when it is in the standby state immediately after the operating state, and the deterioration due to temperature of the material is further reduced. It can be prevented. As an example, an apparatus incorporating a 30 W heater using a POSISTOR has the effect of lowering the temperature by 5 to 6 degrees Celsius at the time when the temperature near the lower surface of the photoreceptor drum reaches its highest immediately after the copying operation is completed. Figure 3 shows cleaner unit 6
This figure shows the temperature change at the bottom of the photosensitive drum 1, where the cooling fan is always in operation and the old dotted curve shows the temperature rise when the conventional heater is always energized. It shows the temperature rise when the cooling fan operates, and the Wc4 diagram shows the temperature fluctuation under the conditions where the air volume of the cooling fan is changed.

【Effect of the invention】

As mentioned above, due to the combined heating of the heater to prevent condensation and the heat source of the fixing device while in operation, the temperature of the entire device rises during and immediately after operation, which has caused material deterioration. However, according to the present invention, it has become possible to provide an electrostatic recording device that eliminates these drawbacks and does not impair the effect of preventing dew condensation at the time of copying operation. In addition, the air volume of the cooling fan 5 is controlled to be increased in the operating state, and to be reduced in the standby state! As shown in FIG. 4, the present invention has a significant effect on the occurrence of overheating caused by a decrease in the air volume of the cooling fan when moving from the operating state T2 to the next standby state T2'. began to bring.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of a copying machine using the present invention, Fig. 2 is an electric circuit diagram showing the connection of a relay circuit, and Figs. FIG. 3 is a diagram showing the difference between the prior art and the present invention. ]...Photosensitive drum 2...Heater 3...Motor 4...Fuser unit 5...Cooling fan 6...Cleaner unit 7...Original table 8...Optical system 9... Transfer paper 11...Power supply 12...Relays A, B, C...Terminals TI, Tl'...Standby state time T2...Operating state time old! 12...Temperature change curve Figure 2

Claims (1)

[Claims] An electrostatic recording device characterized in that heaters provided near the bottom of a photosensitive drum that is driven and rotated by a motor and that performs image formation are electrically switched and controlled by the same relay as the motor.