JPS60201364A - Copying machine - Google Patents

Abstract

PURPOSE:To maintain the temperature of a photosensitive body invariably within a proper temperature range and to hold the performance of the photosensitive body stably by providing a temperature control means to the copying machine which employs an electrostatic photographic method. CONSTITUTION:The photosensitive body is heated by a heat source H which operates all the time regardless of the main switch of the copying machine frame to prevent dew condensation. The temperature in the machine is detected with a thermal reed switch Th as a temperature detecting element; when the detected temperature rises above specific temperature, discharge fan and suction fan F-1 and F-2 as an in-machine ventilating means are started to discharge the warm air in the machine and suck cool air outside the machine, preventing the overheating of the photosensitive body. A triac Tr operates as a switch for the fans F-1 and F-2 and turns on when the thermal reed switch Th turns on.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a copying machine using electrostatography, and more particularly to a copying machine with improved temperature stabilization of a photoreceptor.

[Prior art]

In a copying machine such as a so-called electronic copying machine that uses electrostatic photography, a photoconductive photoreceptor (hereinafter simply referred to as photoreceptor) is charged over its entire surface, and then exposed to image light to create an electrostatic latent image of the subject. After forming a latent image and acclimatizing the latent image by toner development, it is transferred to paper or the like and heated with a heat roller to fix the toner to obtain a copy.

Selenium, zinc oxide, amorphous silicon, cadmium sulfide, various organic photoconducting compounds, etc. are used as photoreceptors, but although their photosensitivity characteristics differ depending on the material, they all have temperature dependence, and are generally temperature dependent. As the temperature increases, the photosensitivity also increases. Therefore, if the temperature of the photoreceptor is too low, toner will adhere to non-image areas, causing fog, and in some cases, the surface of the photoreceptor may become wet due to dew condensation, reducing its insulation properties, making image formation impossible. occurs. On the other hand, if the temperature becomes too high, the image density will decrease, and in even worse cases, the performance of the photoreceptor may deteriorate.

In a practical copying machine, the humidity of the photoconductor is affected not only by the temperature and humidity of the outside air at the installation location, but also by various electrical components installed inside the machine, heat emitted from the image fixing heat roller, etc. This often depends on the operating mode of the device, such as startup, standby, and continuous copying. Therefore, in order to be able to use the copying machine under stable conditions at all times, it is necessary to maintain the temperature of the photoreceptor within a certain appropriate range at all times.

In particular, the above-mentioned occurrence of dew condensation is a serious practical problem, and tends to occur in the mornings of cold seasons, and once it occurs, it becomes impossible to form both images for a long time.

As a means to prevent this, Japanese Patent Application Laid-Open No. 51-6594
Publication No. 1 discloses a method of providing a weak heating element near the photoconductor to keep the surface of the photoconductor in a non-moisture state, while JP-A-53-3231 similarly provides a heater to prevent condensation, and prevents condensation inside the copying machine and machine. Devices have been disclosed that keep the photoconductor and optical system above the outside humidity based on the outside humidity, but none of them limit the upper limit of the photoconductor temperature, but rather keep the photoconductor temperature at an appropriate temperature. It could not be said that it was sufficient.

[Purpose of the invention]

An object of the present invention is to provide a copying apparatus that can maintain stable performance of a photoreceptor.

[Structure of the invention]

The above object is to provide a copying apparatus having a heat source for preventing dew condensation to prevent condensation on an image carrier. This has been achieved by a copying apparatus characterized in that it is equipped with a control means for starting and stopping the means.

In other words, the present invention prevents dew condensation by heating the photoreceptor using a heat source that is constantly activated regardless of the main switch of the copying machine, and detects the temperature inside the copying machine using a detection means provided inside the copying machine to ensure that the temperature remains constant. When the temperature exceeds the temperature, the ventilation means is activated to exhaust warm air inside the machine and draw in cold air from outside the machine, thereby preventing overheating of the photoreceptor.

As a means for ventilating the inside of the copying machine, it is preferable to provide an exhaust fan that exhausts heated air inside the copying machine or an intake fan that takes in cold outside air. You may. Ventilation can be controlled by starting and stopping these fans.

As the control means for starting and stopping the ventilation means, it is possible to use a combination of various known temperature detection elements such as thermistors and various known switching elements such as Lee μ, but thermal reed switches and tria A combination of the following circuits can be used with particular preference.

The temperature at which the ventilation means is started and stopped may be set depending on the appropriate operating temperature of the photoreceptor used.Q).

It is particularly preferable to provide the temperature detecting element near the top of the photoreceptor in order to correspond to the temperature of the photoreceptor.The copying apparatus according to the present invention also includes a heat source for preventing condensation when the internal temperature reaches a certain value or more. It is also possible to provide a heat source control means for preventing dew condensation, which is configured to stop the heat source and restart the heat source when the temperature drops below a certain value.

Furthermore, when copying is performed continuously, heat dissipates from various parts such as the illumination light source and the motor. It is desirable to prevent the temperature from rising. The present invention will be explained in detail below with reference to Examples.

〔Example〕

FIG. 1 is a schematic diagram showing an example of a copying apparatus according to the present invention. A document placed on the document table L is scanned by a moving light source 2, and its image is formed by a plurality of mirror stripes ~M4 and a lens L, which has a photoreceptor (Se in this example) on the surface, and scans the light source 2. Synchronized with.

The photosensitive drum 3 is projected on the rotating photosensitive drum 3.
An electrostatic image is formed thereon. The electrostatic image is developed with toner by the developing device 4. The toner image on the photosensitive drum 3 is indicated by the arrow P.
The image is rolled onto a sheet of paper fed along the path of , and fixed between a heated fixing roller 5 and a pressure roller 6, and then discharged outside the machine as a completed copy.

H is a heater that is used as a heat source to prevent condensation, F-1 and F-2 are exhaust fans and intake fans, respectively, which are the five means of in-flight ventilation, and Th is temperature detection to control the operation of F-1 and F-2. This is a thermal reed switch. F-1,
F-2 is simultaneous operation.

Figure 2 shows the temperature control circuit of this device, which is a triac that works as a switch for 'fr-1 and fans F-1 and F-2, and P is an AC power supply that does not go through the main switch of the copying machine. . When the thermal reed switch is turned on in both circuits of fans F-] and F-2, the triac becomes energized.

R is a relay connected to the main control section of the copying machine, which is turned on while the copying machine is copying, and turns on the fans F-1 and F regardless of the state of the thermal relay switch Th-2.
Activate -2.

The photoreceptor in this example is Se, and its preferred operating temperature range is 15°C to 40°C, so the temperature at which the thermal reed switch Th is turned off is (9)°C, O
A practical test was conducted by setting the temperature of N at 35°C. This device was left in a room at a temperature of 10°C for a long time. During this time, the heater H is continuously energized and heated, the temperature near the thermal reed switch is kept below 20'C, the fans F-1 and F-2 are stopped, and the temperature of the photoreceptor is The temperature was maintained between 15°C and 20'C. For this reason, it was possible to obtain a material with a better image immediately after the main switch was installed.

In addition, 20 sheets/minute in a room with a temperature of about 27 degrees Celsius, 50 sheets per minute on A3 size paper.
Continuous copying of 00 sheets was performed. During copying, the relay shown in Figure 2 R was turned on and the exhaust and intake fans (Fl and F2) were activated to ventilate the cabin, but at the end of copying, the temperature near thermal reed switch Th2 was approximately 40°C. Therefore, fans F-1 and F-2 continued to operate and did not stop until the temperature reached 30'C. For this reason, the photoreceptor temperature was maintained at 40° C. or lower. On the other hand, when the fan was stopped upon completion of copying, the temperature inside the machine further rose due to residual heat, and the temperature of the photoreceptor rose to 40° C. or higher, resulting in unfavorable results.

〔Effect of the invention〕

As seen in the above embodiments, in the copying apparatus equipped with the temperature control means according to the present invention, the temperature of the photoreceptor is always maintained within the appropriate temperature range, so that copies of excellent image quality can be made at any time without being affected by the outside temperature. You can get things stably.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a copying machine showing one example of the present invention. FIG. 2 is a circuit diagram of the temperature control circuit. 3... Photoreceptor H... Anti-condensation heater Tb...
Thermal reed switch Tr...Triac F-1...Exhaust fan F-2...Intake fan agent Patent attorney No. 1) Parent-in-law Figure 1

Claims (2)

[Claims] (1) In a copying apparatus having a heat source for preventing dew condensation to prevent condensation on a carrier, an in-machine ventilation means provided in the copying apparatus and a temperature inside the copying apparatus are detected, and the ventilation means A copying apparatus characterized by comprising a control means for starting and stopping the copying apparatus. (2) The copying apparatus according to claim 1, wherein the temperature sensing portions of the two control means are provided near the top of the image carrier.