JPS61167959A - Dew condensation preventing device of electronic copying machine - Google Patents

Abstract

PURPOSE:To prevent dew condensation by providing a filter which has moisture absorption effect halfway between a photosensitive drum and a heat retaining heater and also providing a switching means which moves the filter. CONSTITUTION:The filter 3' is placed at a dotted-line position in the nighttime and wet and warm air heated by the plane type heat retaining heater 2 is dehumidified when passing through the filter 3' to prevent partial dew condensation 19 on the photosensitive drum 1. The photosensitive drum 1, however, has a slight variation in temperature because the air is passed through the filter, but the temperature in a machine is much higher than room temperature, so that no dew condensation is caused. When a power switch is turned on early in the morning, the filter 3' moves to a solid-line position to put the heat retaining effect of the heat retaining heater 2 directly and heating equipment at other parts of the copying machine is powered on simultaneously, so the temperature in the copying machine rises speedily to prevent a dew condensation state. Consequently, an invariably excellent and stable image is maintained.

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a dew condensation prevention device for copying machines, etc.
In particular, the present invention relates to a dew condensation prevention device suitable for use in electrophotographic copying machines.

2. Description of the Related Art Generally, in electronic copying machines and the like, dew condensation may occur on the surface of the photoreceptor drum as the room temperature rises rapidly, especially in the mornings in winter.

When dew condensation occurs on the surface of the photoreceptor drum, charging failure occurs at that location, resulting in a so-called white-out image. In electronic copying machines, there are various parts other than the photosensitive drum, such as lenses, mirrors, and paper transport systems, that can cause problems due to condensation. Such condensation is caused by water vapor contained in the atmosphere. This occurs due to cooling and condensation, so it occurs when the surface temperature of equipment such as photoreceptors and drums is lower than the internal temperature (room temperature).

Therefore, it has been known to heat all the equipment, including the photoreceptor drum, which should not cause dew condensation, using a heat-retaining heater to keep the surface temperature constant.

However, such a temperature difference does not generally occur during normal use, when the copying machine is turned on and copying, or when it is in standby mode after copying. As described in Japanese Patent Publication No. 58-72160, a system was adopted in which electricity could be supplied to the heater at a temperature below a set temperature via a thermostat.

Problems to be Solved by the Invention In the above-mentioned system, a new problem arises because the photosensitive drum continues to be heated for a long time at night when the copying machine is not in use. That is, it is well known that at night, as the temperature continues to drop as time passes, the relative humidity approaches a saturation point and becomes high. In such an atmosphere, as shown in FIG. 3, when the planar heat-retaining heater 2 disposed near the photoreceptor drum 1 is fully driven to generate heat, the atmosphere above the heater 2 is heated. The atmosphere becomes warmer than other atmospheres, and as it rises, light condensation may occur on the lower surface of the photoreceptor drum 1 that has not yet warmed up.

When this state continues during the night, the other parts of the photoreceptor drum 1 maintain a constant temperature due to the heat generation effect of the heater 2 and are normal, but the humid and warm air at the bottom of the drum The heat retention effect is blocked and dew condensation continues in the area that is in contact with the drum, so when copying the first thing in the morning, the area corresponding to the bottom of the drum is narrow and it is inevitable that the image will be white. It still exists.

Means and Function for Solving the Problems In order to solve the above problems, in the present invention, there is provided a structure that has hygroscopicity and allows the passage of atmosphere between the photoreceptor drum and the heater provided near and below the photoreceptor drum. In addition to disposing a filter made of a material that has properties of heat, a switching means is provided to move the filter on the top surface of the heater.During the night, moist air generated by the heat generated by the heater hits the photoreceptor drum through the filter, thereby maintaining the heat retention effect of the heater. At the same time, moisture is absorbed to prevent dew condensation at the bottom of the drum, and when the power switch is turned on in the early morning, the filter is moved to directly apply the heat retaining effect of the heater to the photosensitive drum, thereby increasing the heater effect.

Example This invention! ! An example will be explained based on the drawings.

In FIG. 3, reference numeral 1 denotes a photoreceptor drum that forms an electrostatic latent image as an image carrier, surrounded by a charging charge 4 that uniformly charges the photoreceptor drum 1, which is guided through a lens 16. A slit exposure unit 5 that irradiates the photoreceptor drum 1 with a light image of an incoming original to form an electrostatic latent image, a developing device 6 that visualizes this latent image with toner, and a paper conveyed from the paper feed unit 15. A transfer charger 7 transfers the toner image on the photoreceptor drum 1 to the photoreceptor drum 1, and a claw 9 separates the paper from the photoreceptor drum l.
A peeling charger 8 that peels off the photoreceptor with zero action, a cleaning device 10 for reusing the photoreceptor, a static elimination charger 11, and the like are provided.

Further, the paper is discharged from the conveyance device 12 via the fixing device 13 to a discharge tray 14 outside the machine. Since the above configuration is similar to that of a conventional electronic copying machine, a detailed explanation of its operation will be omitted.

Reference numeral 2 denotes a planar heat-retaining heater, which is disposed below the photoreceptor drum 1 to keep it warm. In this invention, as shown in FIG. 1, a filter 3' made of a non-woven fabric with an appropriate mesh size as shown in FIG. or a longer length, and is attached to the bracket 3''.

This bracket 3'' is formed by punching in the length direction of the drum, has a certain degree of air permeability through the non-woven fabric filter 3', and is fixed to the tip of the solenoid 17 as shown in FIG. At the same time, one end of the spring 18 is locked to a part of the solenoid 17, and the other end of the spring 18 is locked to a part of the solenoid 17.

In this way, the movement of the filter 3' is switched by the tin ring 8 and the solenoid 17, that is, the filter 3' is given the habit of being able to move in the horizontal direction, and when the power switch of the copying machine is on, the filter 3' is moved in the first position. It is located at the solid line position in the figure, and moves to the dotted line position when turned off.

Next, the operation of this device will be explained.

During the night, the filter 3' is placed at the position indicated by the dotted line, and the moist, warm air generated by the heat generated by the sheet heater 2 absorbs moisture as it passes through the filter 3', and the photoreceptor drum 1 is heated as described above.
19t - Prevent partial condensation. However, photoreceptor drum 1
Although the temperature is slightly increased by passing through the filter 3', condensation does not occur because the temperature inside the machine is much higher than the room temperature.

When I turn on the power switch early in the morning, filter 3
' moves to the solid line position, and the heat retention effect of the planar heater 2 is no longer directly maintained, and power is also supplied to other parts of the copying machine, such as the fixing device, at the same time, so the temperature inside the copying machine decreases. will increase dramatically. In this way, the temperature inside the machine is always maintained above a certain level due to the sudden increase in the indoor atmosphere due to the use of heating, thereby preventing the occurrence of dew condensation.

Note that if you turn on the power switch too soon before turning on the heater, warm, humid air will accumulate on the photoreceptor drum 1, causing slight condensation, but this will cause the internal temperature of the machine to rise and the room temperature to rise. It goes without saying that this initial cloudiness (condensation) dries and disappears as the relative humidity decreases, so it is not a particular problem.

Further, in the above embodiment, a non-woven fabric was used as the material for the filter 3', but other materials may be used, and a non-woven fabric with coconut shell activated carbon mixed therein is highly effective. Further, the means for moving the filter 3' is not limited to the above-mentioned horizontal movement, but other moving means such as rotation, vertical movement, etc. may be used.

Effects of the Invention As described above in detail L7, the present invention provides a filter made of a material that is hygroscopic and allows the atmosphere to pass through between the heater provided near and below the photoreceptor drum and the photoreceptor drum. The heat insulating effect of the heater is maintained, and moisture is absorbed to prevent condensation at the bottom of the drum, thereby preventing local condensation from forming on the photoreceptor drum due to the heat insulating effect of the heater at night. As a result, it is possible to eliminate the occurrence of partial white-out images and to maintain a good and stable image at all times.

Furthermore, when the copier is turned on and is used for regular use, the filter can be moved from the top of the heater to further enhance the heater effect.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the main parts of the dew condensation prevention device for an electronic copying machine according to the present invention, FIG. 2 is a partial schematic diagram of a filter and bracket used in the dew condensation prevention device of the present invention, and FIG. 3 is a diagram showing the conventional device and the present invention. 1 is a schematic diagram showing the internal configuration of an electronic copying machine common to the above. 1... Photosensitive drum, 2... Planar heat retention heater, 3'
...Filter, 3"...Bracket, 17...Solenoid, 18...Spring.

Claims (1)

[Claims] In an electronic copying machine having a dew condensation prevention device including a heat-retaining heater near the photoreceptor drum, a filter having a moisture absorption effect is installed between the photoreceptor drum and the heat-retaining heater, and a switching means for moving the filter is provided. A dew condensation prevention device for an electronic copying machine, characterized in that it is provided with a dew condensation prevention device.