JPS6364059A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of defective images at the starting time of use by providing heating means for an image carrier and a fixing device and heating the image carrier more quickly than the fixing device when a power source of a device is turned on. CONSTITUTION:A surface heating body 16 is provided to a photosensitive drum 4, and heaters 20 and 21 are provided to a roller 18 of a fixing device 13. Power supply to the surface heating body 16 and heaters 20 and 21 is controlled at the time of power-on so than the photosensitive drum 4 reaches a prescribed temperaure more quickly than the fixing device 13. Since the surface temperature of the photosensitive drum 4 reaches the prescribed value more quickly than that of the roller 18 of the fixing device, the copying operation is possible even just after power-on, and the occurrence of defects such as image flow is eliminated under high temperature and high humidity. Since the image carrier is heated more quickly than the fixing device, the occurrence of defective images is prevented when the power source is turned onto start the use after power is broken.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image forming apparatus such as a copying machine, and particularly to an image forming apparatus having means for heating an image carrier.

(Prior Art) Conventionally, as a copying machine of this type, there is one in which a heater is provided in the photoreceptor drum so that stable image quality can be obtained even when the surface of the photoreceptor drum is maintained at a constant temperature. The heater is energized even when the device is not in use, for example at night.
As long as the fuser reaches the specified temperature when the device is first used, stable image quality can be achieved under any environment or conditions.
Copies can be made directly.

(Problems to be Solved by the Invention) However, such prior art has the following problems. That is, in buildings where the power supply is centrally controlled, the power to the entire building is cut off at a certain time, and the power to the heaters is turned off. Therefore, even if the entire building is powered on the next day and the heaters are energized, it takes too long for the photoreceptor drum to reach the predetermined temperature, and when the 77th base reaches the predetermined temperature, the copying machine starts copying. Even when the photoreceptor drum is in a weak state, the photoreceptor drum may not yet reach a predetermined temperature. If copying is performed in this state, especially in a high-temperature, high-humidity environment, moisture will adhere to the surface of the photoreceptor drum and the image on the photoreceptor drum will become blurred. There was a 14th fortune telling that the 7M image was hidden.

The above-mentioned problem also occurs in buildings where the power supply is centrally controlled and when the copying machine is unplugged for safety reasons such as fire prevention when returning home.

Therefore, the present invention has been made to solve the above-mentioned problems of the prior art.The purpose of the present invention is to solve the problem of the above-mentioned conventional technology. An object of the present invention is to provide an image forming apparatus that can prevent the occurrence of defective images.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a heating means 17 for heating an image bearing member to a predetermined temperature, and transfers an image formed on the image bearing member. In an image forming apparatus that forms an image by fixing the image on the transfer material using a fixing means heated to a predetermined temperature after transferring the image onto the material, when the power of 821 is turned on,
The image carrier is configured to be heated to a predetermined temperature faster than the fixing means.

(Function) In the present invention, when the power of the apparatus is turned on, the image bearing member is heated to a predetermined temperature higher than the fixing means, so that the image bearing member is always heated to the predetermined temperature when the image forming operation becomes possible. Since it is heated, image defects will not occur.

(Example) The present invention will be explained below based on illustrated embodiments.

FIG. 1 shows a copying machine as an embodiment of an image forming apparatus according to the present invention. In FIG. The image is transferred to a photosensitive drum 4 as an image carrier via an optical system 3.
projected on top. The outer peripheral surface of the photoreceptor drum 4 is a photoreceptor layer, and rotates about the drum shaft 5 in the direction of the arrow in the figure. The surface of the photoreceptor drum 4 is first uniformly charged by a primary charger 6.
As described above, an original image is projected, and the portion irradiated with light is charged and an electrostatic latent image is formed. This electrostatic latent image is developed by a developing device 7 or 8, and an image developed with toner is formed on the surface of the photoreceptor drum 4. The developed image on the surface of the photosensitive drum 4 is transferred by a transfer charger 10 onto a transfer paper (not shown) fed from a paper feed section 9. The transfer paper is separated from the photosensitive drum 4 by a separation charger 11 and conveyed to a conveyor belt 12. The transfer paper passes through the fixing device 13 to have the unfixed image fixed thereon, and then is discharged onto the paper discharge tray 14 . On the other hand, the toner remaining on the photosensitive drum 4 is cleaned by a cleaner 15 and enters the first process. In addition, in the figure, F indicates the transfer path of the transfer paper when double-sided copying or multiple duplex copying is performed.

A planar heating element 16 is disposed inside the photoreceptor drum 4 to uniformly heat the photoreceptor drum 4. As shown in FIG. 2, this planar heating element 16 is constructed by embedding two heaters 16a and 16b as heating means in a flexible plastic sheet 16c. The planar heating element 16 is inserted into the photoreceptor drum 4 in a substantially cylindrical shape, and is arranged so as to uniformly contact the inner circumferential surface of the photoreceptor drum 4 due to its elastic restoring force. There is. As a result, the planar heating element 16 rotates around the drum shaft 5 integrally with the photosensitive drum 4. Further, a thermistor 17 is in contact with the inner surface of the photoreceptor drum 4, and the temperature of the photoreceptor drum 4 is detected by this thermistor 17, and the heaters 16a, 16 are controlled by a control circuit to be described later.
By controlling the current supply to b, the temperature of the photosensitive drum 4 is always kept constant.

Further, in the fixing device 13, an upper roller 18 and a lower roller 19 are arranged to fix an unfixed image on the transfer paper. Halogen heaters 20 and 21 are fixed inside the upper roller 18, and the upper roller 18
, 21. Lower roller 19 is F roller 1
8 is pressed against the upper roller 18 to form a predetermined nip. Therefore, the unfused image on the transfer paper is fixed to the transfer paper by both heat and pressure.

Further, a thermistor 22 is in contact with the outer peripheral surface of the upper roller 18, and the thermistor 22 causes the upper roller 18 to
The lighting time of the heaters 20 and 21 is controlled to keep the surface temperature constant.

The reason why the two heaters 20 and 21 are provided in the fixing unit W13 is that when the main switch of the copying machine is turned on, both heaters 20 and 21 are energized and the fixing device 13 is rapidly heated. This is to shorten the waiting time. Fuser 1
3 reaches a predetermined temperature, one of the two heaters is completely turned off, and the remaining one heater is repeatedly turned on and off to adjust the temperature of the fuser 13. The idea is that the rest of the copying machine remains inoperable until a predetermined temperature is reached, so the remaining power is directed to the fixing device.

In Figure 3, which is a block diagram showing the control system,
23 is the main switch of the copying machine, 17° 22 is a thermistor, 24 is a control circuit that controls the operation of the copying machine, 16a,
16b is a heater that heats the photosensitive drum 4, 20.21
is a halogen heater of the fixing device 13.

In the above configuration, in the copying machine according to this embodiment, heating control of the photosensitive drum and the fixing device is performed as follows. That is, the control circuit 24 controls the main switch 2
3 is turned on, the heaters 16a, 16b and the halogen heater 20 are turned on according to the sequence shown in FIG.
, 21. To explain this in detail, at the same time that the main switch 23 of the copying machine is turned on, the two heaters 1 of the planar heating element 16 that heat the photoreceptor drum 4 are turned on.
6a, 16b, and one halogen heater 20 that heats the fixing device 13 are started to be energized. The temperature of the photosensitive drum 4 is detected by the thermistor 17, and the temperature of the photosensitive drum 4 is detected after T1 time 'j! When the photoreceptor drum 4 reaches a predetermined temperature control temperature after 4, the control circuit 24 stops power supply to one heater 16b and turns the other heater 16a on and off.
This is repeated to maintain the photosensitive drum 4 at a predetermined temperature. Further, when the power to the heater 16b of the photosensitive drum 4 is turned off after the time T1 has elapsed, the control circuit 24 controls the fixing 813.
The halogen heater 21 starts to be energized. After that, 1
After 2 hours have passed, the fixing $13 also changes to the thermistor 22.
The controlled temperature is reached. At this time, the control circuit 24 stops the current supply to one halogen heater 21 and repeats turning on and off the other halogen heater 20 to keep the surface temperature of the upper roller 18 of the fixing device 13 constant. In the case of humidity, the copying operation is performed only in this state, that is, after Tl+"r2 hours have elapsed since the main switch 23 was turned on.

In this way, the surface temperature of the photoreceptor drum 4 always reaches the predetermined temperature before the surface temperature of the upper roller 18 of the fixing device 13, so even if the photoreceptor drum 4 is enabled for copying operation even immediately after the power is turned on, the photoreceptor drum 4 Since the heater 16a of the photosensitive drum 4 is heated to a predetermined temperature, there is no risk of image defects such as image deletion even in a high temperature and high humidity environment.

16b and the halogen heaters 20 and 21 of the fixing device 13,
Since they are not energized at the same time, power consumption during the waiting time can be reduced.

In addition, in an apparatus in which the photoconductor drum and the fixing device each have two heaters as in this embodiment, it is possible to use heaters each having different power consumption. If you use a large one, the waiting time will be T.

time can be shortened.

In the above embodiment, the case where the photoconductor drum and the fixing device each have two heaters has been described, but the case where the photoconductor drum and the fixing device each have one heater or only one has two heaters is also possible. Applicable. In this case, if the input to the heaters of the photoconductor drum and the fixing window are both female wave input, the heater of the photoconductor drum should be a full wave input within time T1 in FIG. 4, and the heater of the fixing device should be a half wave input. Assume wave input. Thereafter, the temperature of the heater of the photosensitive drum is controlled by half-wave input, while the heater of the fixing device is switched to full-wave input after time T1 has elapsed. After the T2 time has elapsed, the fuser heater may continue to perform temperature control using full-wave input, or
You may switch to half-wave input again and repeat the temperature control.

(Effects of the Invention) The present invention has the above configuration and operation, and even if the power supply to the device is cut off at night, etc., it is possible to prevent a defective image from occurring when the device starts to be used. be able to.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing a copying machine as an embodiment of an image forming apparatus according to the present invention, FIG. 2 is a plan view showing a planar heating element, and FIG. 3 is a block diagram showing a control system. FIG. 4 is a timing chart showing the operation of the control system. Explanation of symbols 4...Photosensitive drums 16a, 16b--Heater 13...Fixer 20.21...Halogen heater 24...Control circuit Fig. 2 Fig. 3

Claims (1)

[Claims] It has a heating means for heating the image carrier to a predetermined temperature, and after transferring the image formed on the image carrier onto a transfer material, the image is fixed on the transfer material by a fixing means heated to a predetermined temperature. 1. An image forming apparatus that forms an image by heating the image carrier to a predetermined temperature earlier than a fixing means when the apparatus is powered on.