JPH08225169A - Image forming device - Google Patents

Abstract

PURPOSE: To dispense with installation of a humidity sensor so as to prevent increase in a cost by controlling electric power for a dehumidifying heater on the basis of an outputted condition of a temperature detecting element used for temperature control for the part other than a paper feeding tray part. CONSTITUTION: An output of a fixing roller temperature detecting element 4a controlling a temperature of a fixing roller is led to a dehumidification controlling means 3, and the dehumidification controlling means 3 actuates switches GW-1, SW-2 so as to supply electric power to a dehumidifying heaters 2 (2a, 2b) in paper feeding tray 1a, 1b only while it is determined that a temperature of the fixing roller is low and dehumidification of a transfer paper is not sufficiently carried out. For a temperature detecting element 4 detecting an internal temperature of the device, a drum temperature detecting element 4b of a photosensitive drum or another temperature detecting element 4c can be used. In this way, a dedicated humidity sensor for dehumidifying the transfer paper is not especially required, so that dehumidification can be carried out without any increase in a cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine, a laser printer and a facsimile,
In particular, the present invention relates to an image forming apparatus having a function of dehumidifying transfer paper in a paper feed tray.

[0002]

2. Description of the Related Art In an image forming apparatus having a function of dehumidifying transfer paper in a paper feed tray, a humidity sensor is installed in the paper feed tray in the immediate vicinity of the transfer paper so that the humidity based on the humidity detected by the humidity sensor is detected. Power of the dehumidifying heater is turned on and off to control the humidity of the paper (Japanese Patent Application Laid-Open No. Hei 4-
No. 94337), a method of turning on / off the power of the dehumidifying heater by a weekly timer, or a method of supplying power to the dehumidifying heater only when power is not supplied to the fixing device (see Japanese Utility Model Laid-Open No. 1-74341). It was being done. However, in the former method of providing the humidity sensor, there are many cases in which the humidity sensor is exposed to dew or the like and normal dehumidification control cannot be performed, or the humidity sensor is expensive, which increases the cost of the apparatus. If the dehumidifying heater is turned on by the weekly timer, or if the dehumidifying heater is turned on only when power is not supplied to the fixing device, the dehumidifying heater is turned on immediately after image formation even when the temperature inside the image forming device is high. There is a problem that power is wasted and the temperature rise in the image forming apparatus becomes unnecessarily high.

[0003]

In the above-mentioned conventional technique, it is said that the cost is increased, the power consumption is wasted, and the temperature rise in the image forming apparatus is unnecessarily increased to shorten the life of the apparatus. There was a problem.

[0004]

SUMMARY OF THE INVENTION Therefore, according to the present invention, a temperature detecting element used for temperature control other than a sheet feeding tray portion in an image forming apparatus is used together with a detecting element of a dehumidifying control means for controlling electric power of a dehumidifying heater. This prevents the cost from increasing and the dehumidifying heater is turned on only when the temperature of the fixing roller or the temperature of the photosensitive drum is lower than a predetermined temperature, so that the transfer paper can be dehumidified regardless of the external environment. It is an object of the present invention to provide an image forming apparatus that eliminates paper jams, saves power consumption, suppresses unnecessary temperature rise in the image forming apparatus, and improves the safety and life of the apparatus.

[0005]

In order to achieve the above object, the present invention provides an image forming apparatus having a function of dehumidifying the transfer paper in the paper feed tray, and a paper feed tray for storing the transfer paper, and A dehumidifying heater provided for dehumidifying the transfer paper in the paper feed tray; and a dehumidifying control means for controlling the electric power of the dehumidifying heater.
The most main feature is that the image forming apparatus controls the electric power of the dehumidifying heater based on the output condition of the temperature detecting element used for temperature control other than the sheet feeding tray section in the image forming apparatus.

In the image forming apparatus described in the item 1, while the dehumidifying control means detects that the fixing roller temperature of the fixing device is equal to or lower than a predetermined temperature, The main feature of the image forming apparatus is that the dehumidifying heater is turned on. In the image forming apparatus according to the above item 1, the dehumidification control unit operates the dehumidification heater while the drum temperature detection element detects that the drum temperature of the photosensitive drum is equal to or lower than a predetermined temperature. The main feature is that the image forming apparatus is turned on.

In the image forming apparatus described in the above items 1, 2, and 3, a tray moving means for moving the paper feed tray up and down and a weekly timer for changing the operating state of the image forming apparatus at a set time are provided. Having the power supply of the weekly timer, by lowering the paper feed tray by the tray moving means and separating the transfer paper from the calling roller, the dehumidification control means is used in the image forming apparatus. The most main feature of the image forming apparatus is that the dehumidifying heater is turned on while detecting that the temperature detecting element is below a predetermined temperature. In the image forming apparatus described in the item 4, the main feature is that the tray moving means is an image forming apparatus in which a position for lowering the paper feeding tray can be selected stepwise.

[0008]

The image forming apparatus configured as described above includes a paper feed tray for storing transfer paper, a dehumidifying heater provided for dehumidifying the transfer paper, and a dehumidifying control means for controlling electric power of the dehumidifying heater. In addition, since the power supplied to the dehumidification heater is controlled by the dehumidification control unit based on the output condition of the temperature detection element used for temperature control other than the paper feed tray section, the output of the temperature detection element has a predetermined value. In the following cases, power is supplied to the dehumidification heater through the dehumidification control means,
The transfer paper in the paper feed tray can be dehumidified. Further, when the output of the temperature detecting element becomes equal to or higher than a predetermined value, the heat is spread to the inside of the image forming apparatus, the temperature inside the apparatus becomes high, and it is not necessary to dehumidify the transfer paper. Cut. In this way, the transfer paper can be dehumidified without the need to provide an expensive humidity sensor for dehumidifying the transfer paper.

With the dehumidifying control means according to the first aspect, the dehumidifying heater is turned on while the fixing roller temperature detecting element detects that the fixing roller temperature of the fixing device is lower than a predetermined temperature. Since it is
It is possible to omit the dedicated detection element of the dehumidification control means that controls the electric power of the dehumidification heater, and the dehumidification heater can be operated only while the temperature of the fixing roller is low and the temperature inside the device does not warm up, and the dehumidification of the transfer paper is not sufficient. Since the light is turned on, power consumption can be saved and unnecessary temperature rise in the image forming apparatus can be suppressed.

With the dehumidifying control means according to the first aspect, the dehumidifying heater is turned on while the drum temperature detecting element detects that the drum temperature of the photosensitive drum is below a predetermined temperature. Therefore, it is possible to omit the dedicated detection element of the dehumidification control means for controlling the electric power of the dehumidification heater, and the dehumidification heater can be used only while the drum temperature is low and the temperature inside the device does not warm up and the dehumidification of the transfer paper is not sufficient. Is turned on, it is possible to save power consumption and suppress unnecessary temperature rise in the image forming apparatus.

A paper feed tray for storing the transfer paper, a tray moving means for moving the paper feed tray up and down, a dehumidifying heater provided for dehumidifying the transfer paper, and a dehumidifying control means for controlling the electric power of the dehumidifying heater. Having a weekly timer that can change the operating state of the image forming device at a set time, the paper feed tray is lowered by the tray moving means when the power of the weekly timer is turned off, and after the transfer paper is separated from the calling roller, the above dehumidification control is performed. Since the dehumidifying heater is turned on by the means, the dehumidifying heater is not turned on when the transfer paper in the paper feed tray is pressed by the calling roller, and the transfer paper can be dehumidified to prevent curling. .

By the tray moving means in the above item 4, the position where the paper feed tray is lowered can be selected stepwise, so the lowered position of the paper feed tray can also be selected according to the temperature detected by the temperature detecting element and the like. As a result, it is possible to eliminate the excessive dehumidification or incomplete dehumidification of the transfer sheet.

[0013]

Embodiments of the present invention will now be described with reference to the drawings. Here, a copying machine will be described as an example of the image forming apparatus, but the same applies to other image forming apparatuses described in the field of industrial use. Further, since the structure and function of the copying machine are general, only an outline will be described. FIG.
FIG. 4 is a schematic configuration explanatory view of an example of an image forming apparatus to which the present invention is applied. A reading optical system 21 includes a light source 22 for irradiating a document with light and a mirror group for guiding document reflected light to a condenser lens 23. 24, a reading element 25 for reading the collected reflected light, and a reading unit fan 26 for releasing the heat generated from the light source 22 to the outside.

In the writing optical system 27, light from a light emitting source (not shown) is reflected by a polygon mirror 28 which is set to match the timing, is condensed by a lens group 29, and is mirrored in a predetermined direction. The photoconductor drum 6 that is already charged by the charger 31
It leads to the surface of and forms an electrostatic latent image that matches the read image.
This electrostatic latent image is visualized by the toner carried by the developing roller 32 that constitutes the developing device. On the other hand, the transfer paper in one or a plurality of paper feed trays 1 is fed to a predetermined position of the photoconductor drum 6 by the calling roller 9 and the paper feed roller 33, and the photoconductor drum 6 rotates (in the arrow direction). After transferring the toner image visualized by the transfer charger 34 to the transfer paper, the charge given to the transfer paper is removed by the separation charger 35 and the transfer paper is exposed to the light. The toner image is separated from the body drum 6, and the toner image is thermally fixed on the transfer sheet by the fixing device 5 mainly composed of the fixing roller 5a and the pressure bonding roller 5b. The toner remaining on the surface of the photosensitive drum 6 after the toner image is transferred onto the transfer paper is removed by the cleaning unit 36, and the next photosensitive and electrostatic latent image is reserved. The exhaust fan 37 exhausts the heat of the entire device. The transfer sheet on which an image has been formed is conveyed by a sheet discharge roller 38, and is stored in any of a sheet discharge tray (not shown).

The above is a copying machine having a reading system and a writing system. However, a laser printer or the like which does not have a reading system naturally does not have the above-mentioned reading optical system 21, so that an external device (not shown) may be used. The writing optical system 27 is operated in accordance with the image forming information, and an image is formed as described above. Further, a dehumidifying heater 2 for dehumidifying the transfer sheet is attached inside the sheet feeding tray 1. In this example, two paper feed trays 1 are arranged, but it goes without saying that any number may be provided.

FIG. 2 is a block diagram around the dehumidification control means 3 of the present invention. Power switch (POWER S
When the power of W) is turned on, the power supplied via the AC input plug 11 activates the DC power supply 12 to supply power to each part. The DC voltage is also supplied to the dehumidification control means 3, which is one of them, and the operation state is entered. In the initial stage of turning on the power switch, the inside of the image forming apparatus shown in FIG. 1 is close to the external environment, and the transfer paper in the paper feed tray 1 is often in a high humidity state. Therefore, if it is used as it is, the electrostatic latent image on the photoconductor drum 6 is not transferred well, or the paper is wrinkled by being rapidly heated and pressed by the fixing roller 5a of the fixing device 5, or when it is conveyed. This causes problems such as not being able to feed the paper normally and causing paper jams.

However, the heat source in the image forming apparatus, for example,
When the temperature inside the apparatus increases due to the fixing roller 5a of the fixing device 5 shown in FIG. 1, the light source 22 for irradiating the original, the heat source added so as not to condense the photosensitive drum 6, and the like,
The transfer paper in the paper feed tray 1 is also naturally dehumidified, and there is no problem in use. This can be said even in a normal use state, and when the heat source of each part is turned off in order to save power consumption in the standby state, the temperature in the device becomes low and the transfer paper in the paper feed tray 1 is also reduced. The same problem as described above occurs when it gets cold and has a high humidity, or when the transfer paper placed in the external environment is additionally used. Therefore, a dehumidifying heater 2 such as a sheathed heater using a heating wire is attached to the bottom of the paper feed tray 1 shown in FIG. 1, and by heating the bottom of the paper feed tray 1, heat is diffused and transferred as a whole. The paper can be warmed and dehumidified (Fig. 1
Dehumidifying heater 2).

Therefore, the output of the fixing roller temperature detecting element 4a which controls the temperature of the fixing roller 5a of the fixing device 5 is led to the dehumidification control means 3 so that the temperature of the fixing roller 5a is low and the transfer paper is sufficiently dehumidified. The dehumidification control means 3 switches (SW-1, SW-2) only while it is determined that there is no
Dehumidifying heater 2 of paper feed tray 1 (1a, 1b)
Power is supplied to (2a, 2b). When the temperature of the fixing roller 5a is lowered and the temperature inside the apparatus is lowered in this way, the dehumidifying heater 2 of the paper feed tray 1 is turned on to dehumidify the transfer paper in the paper feed tray 1. Further, when the temperature of the fixing roller 5a rises and the inside of the apparatus warms up, and the transfer paper in the paper feed tray 1 is naturally dehumidified, the dehumidification heater 2 is turned off so that the temperature inside the apparatus is not unnecessarily raised. There is. The temperature detecting element 4 for detecting the temperature in the apparatus is not limited to the fixing roller temperature detecting element 4a described above, and for example, the drum temperature detecting element 4b for detecting the drum temperature of the photosensitive drum may also be used. Although not shown, it is also possible to use another temperature detecting element 4c that detects the temperature inside the apparatus and controls the operation of the exhaust fan 37.

Further, the dehumidification control means 3 includes a micro CP.
It holds U and a timer, and can function as a weekly timer together with an input instruction from the operation unit 13. This weekly timer is, for example, from Monday to Friday, the power is turned on every day at 8 am (copying is possible immediately), and at 9 o'clock every day, the power is turned off (partially powered standby state). On Saturday and Sunday, it is possible to freely set the combination such that the power is turned off all day. Further, the dehumidification control means 3 takes in the output of the paper end detection element to detect that the transfer paper in the paper feed tray 1 is exhausted, and controls the paper feed tray motor for driving the paper feed tray 1 up and down. You can do it.

FIG. 3 is an explanatory view for explaining the fixing roller temperature detecting element 4a for controlling the temperature of the fixing roller 5a. A pressure contact roller 5b is attached so as to be in pressure contact with the fixing roller 5a, and a portion between them is visible. The transfer sheet bearing the imaged toner image is heated when passing, and the toner image is fixed on the transfer sheet. In order to give this heat, a flickering halogen lamp 5c is built in the fixing roller 5a,
A fixing roller temperature detecting element 4a such as a thermistor is attached in contact with the surface of the fixing roller 5a in order to maintain the temperature range required for fixing. Since the temperature of the surface of the fixing roller 5a becomes extremely high (about 200 ° C.), a large amount of heat is dissipated in the apparatus. Further, when the power of the weekly timer is off or in the standby state where the copy operation is not performed for a long time, the halogen lamp 5c is completely turned off, or the halogen lamp 5c is repeatedly turned on and off at a fast cycle to lower the temperature of the fixing roller 5a. I'm keeping it. Therefore, in either case, the temperature inside the apparatus is lowered to cause the problems described above. Further, the operation of the drum temperature detecting element 4b (FIG. 2) of the photosensitive drum and the other temperature detecting elements 4c (FIG. 2) are also the same, and therefore omitted.

FIG. 4 illustrates a method of preventing curling of the transfer paper by lowering the position of the paper feed tray or the transfer paper when the power of the weekly timer is turned off.
During a normal copying operation, the paper feed tray 1 is moved upward so that the upper surface of the transfer paper is pressed against the calling roller 9. Even after the power of the weekly timer is cut off, if the dehumidifying heater 2 is repeatedly turned on and off while the roller 9 is still in pressure contact with the transfer paper, the transfer paper on the uppermost side will be greatly curled, and during transfer. A paper jam problem occurs. Therefore, in the present invention, the tray moving means 7 lowers the paper feed tray 1 together with the bottom plate 1A to separate the transfer sheet from the calling roller 9, and then the dehumidifying heater 2 is turned on. Curl is gone. Further, as shown in the figure (three places in the figure), the tray moving means 7 makes it possible to select the position where the paper feed tray 1 is lowered stepwise, so that the transfer paper is not dehumidified excessively or incompletely dehumidified. As a result, it is possible to provide an image forming apparatus that can obtain a stable image by eliminating the above-mentioned image loss during transfer and paper wrinkles that occur during fixing.

FIG. 5 is a flow chart for explaining the main operation performed when the power of the weekly timer is turned off, as one operation example of the present invention. When the power of the weekly timer is cut off (YES in step S1), as long as transfer paper remains in the paper feed tray 1 (YES in S2), the tray moving means 7 lowers the paper feed tray 1 to separate the transfer paper from the calling roller 9. (S3). Further, as long as the power supply of the weekly timer continues (S4 NO), the temperature detecting element 4 for detecting the temperature like the temperature control of the fixing roller 5a.
Is output by the dehumidifying control means 3 and waits for the temperature to fall below a predetermined temperature (S5 YES), the dehumidifying heater 2 is turned on, and dehumidification of the transfer paper in the paper feed tray 1 is started (S6). When the temperature detecting element 4 reaches or exceeds the predetermined temperature (YES in S7), it is determined that the temperature inside the apparatus becomes sufficiently high to naturally dehumidify the transfer sheet, and the temperature inside the apparatus is no longer used. The dehumidifying heater 2 is extinguished so as not to raise it (S8). The above blinking of the dehumidifying heater 2 cancels the power-off of the weekly timer (S
4 YES) Continues unless otherwise specified.

In this example, the temperature of the fixing roller is used as a reference for turning on the dehumidifying heater 2, and the temperature detecting element 4 for detecting the temperature of the fixing roller is shown. However, this is only an example, and the temperature of the photosensitive drum is shown. The operation of the dehumidifying heater 2 may be controlled based on detection signals from the detection element and other temperature detection elements.

[0024]

According to the first aspect of the present invention, the paper feed tray 1 for storing the transfer paper, the dehumidifying heater 2 provided for dehumidifying the transfer paper, and the dehumidifying for controlling the electric power of the dehumidifying heater. The temperature detecting elements 4a, 4b, 4c, which are provided with the control means 3 and are used for temperature control other than the paper feed tray portion
Since the electric power of the dehumidifying heater 2 is controlled by the dehumidifying control means 3 from the output condition of No. 2, when the output of the temperature detecting element becomes equal to or less than a predetermined value, the dehumidifying heater is supplied with electric power and supplied. The transfer paper in the paper tray can now be dehumidified. Further, when the output of the temperature detecting element becomes equal to or higher than a predetermined value, heat also spreads to the inside of the image forming apparatus and the temperature inside the apparatus also rises, so that it is not necessary to dehumidify the transfer sheet. I tried to cut off the supply. In this way, there is no need to provide an expensive humidity sensor to dehumidify the transfer paper, so the cost can be prevented from increasing, and the transfer paper can be dehumidified, eliminating paper jams during transport, saving power consumption, and forming images. It is possible to suppress unnecessary temperature rise in the device and improve the safety and life of the device.

With the dehumidification control means according to the first aspect, the dehumidifying heater is turned on while the fixing roller temperature detecting element detects that the fixing roller temperature of the fixing device has become equal to or lower than a predetermined temperature. It is possible to omit the detection element dedicated to the dehumidification control means for controlling the electric power of the dehumidification heater, and to prevent the cost increase for the humidity sensor. Also, since the fixing roller temperature is low and the temperature inside the device does not warm up, and the dehumidifying heater is turned on only while the transfer paper is not sufficiently dehumidified, the transfer paper can be dehumidified regardless of the external environment. It has become possible to eliminate paper jams during transportation due to the above, save power consumption, suppress unnecessary temperature rise in the image forming apparatus, and improve the safety and life of the apparatus.

Since the dehumidifying control means according to the first aspect controls the dehumidifying heater to be turned on while the drum temperature detecting element detects that the drum temperature of the photosensitive drum has become equal to or lower than the predetermined temperature. It is possible to omit the detection element dedicated to the dehumidification control means that controls the electric power of the dehumidification heater, and prevent an increase in the cost of the humidity sensor. Also,
Since the fixing roller temperature is low and the temperature inside the device does not warm up, and the dehumidifying heater is turned on only while the transfer paper is not sufficiently dehumidified, the transfer paper can be dehumidified regardless of the external environment. It is possible to eliminate clogging, save power consumption, suppress unnecessary temperature rise in the image forming apparatus, and improve the safety and life of the apparatus.

In another embodiment of the present invention, a paper feed tray 1 for storing transfer paper, a tray moving means 7 for moving the paper feed tray up and down, and a dehumidifying heater 2 provided for dehumidifying the transfer paper. And a dehumidifying control means 3 for controlling the electric power of the dehumidifying heater, and a weekly timer 8 for changing the operating state of the image forming apparatus at a set time. When the weekly timer is powered off, the tray moving means lowers the paper feed tray. After the transfer sheet is separated from the calling roller 9, the dehumidifying heater is turned on by the dehumidifying control means, so that the transfer sheet can be dehumidified regardless of the external environment and the transfer sheet can be prevented from curling. I was able to do it. Further, it has become possible to eliminate paper jam during transportation, save power consumption, suppress unnecessary temperature rise in the image forming apparatus, and improve the safety and life of the apparatus.

Since the position for lowering the paper feed tray is made selectable stepwise by the tray moving means in the above item 4, the position selected by the temperature detected by the temperature detecting element can also be made possible, and the transfer can be performed. Since it is now possible to eliminate the condition of excessive dehumidification or incomplete dehumidification of the paper, it is possible to use a transfer paper with a dehumidifying condition that matches the transfer conditions, and in addition to the effect of the above item 4, An image forming apparatus capable of obtaining a stable image can be provided.

[Brief description of drawings]

FIG. 1 is a side view of a main part of an image forming apparatus showing an embodiment of the present invention.

FIG. 2 is a block diagram of a main part connected to a dehumidification control unit of the image forming apparatus according to the exemplary embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating a main part of a fixing device of a conventional image forming apparatus.

FIG. 4 is an explanatory diagram illustrating the operation of the paper feed tray of the image forming apparatus according to the embodiment of the present invention.

FIG. 5 is a flowchart showing a main operation of a main part of the image forming apparatus showing the embodiment of the invention.

[Explanation of symbols]

1 ... Paper feed tray, 2 ... Dehumidifying heater, 3 ... Dehumidifying control means, 4 ... Temperature detecting element, 4a ... Fixing roller temperature detecting element, 4b ... Drum temperature detecting element, 5
... Fixing device, 5a ... Fixing roller, 5b ... Pressing roller, 5c ... Halogen lamp, 6 ... Photosensitive drum, 7 ... Tray moving means, 8 ... Weekly timer, 9 ... Calling roller, 11 ... AC input plug, 12 ... DC power supply, 13 ... Operation part, 21
... reading optical system, 22 ... light source, 23 ... condensing lens, 24 ... mirror group, 25 ... reading element, 26 ... reading fan, 27 ... writing optical system , 28 ... Polygon mirror, 29 ... Lens group, 30 ... Mirror, 31 ... Charging charger, 3
2 ... Developing roller, 33 ... Paper feeding roller, 34 ...
Transfer charger, 35 ... Separation charger, 36 ...
・ Cleaning unit, 37 ... Exhaust fan, 38
・ ・ ・ Paper rolls.

Claims (5)

[Claims] 1. An image forming apparatus having a function of dehumidifying transfer paper in a paper feed tray, a paper feed tray for storing transfer paper, and a dehumidification provided for dehumidifying transfer paper in the paper feed tray. It has a heater and a dehumidification control means for controlling the electric power supplied to the dehumidification heater, and the dehumidification control means outputs the temperature detection element used for temperature control other than the paper feed tray section in the image forming apparatus. An image forming apparatus characterized in that the power of the dehumidifying heater is controlled according to conditions. 2. The dehumidifying control means turns on the dehumidifying heater while the fixing roller temperature detecting element detects that the fixing roller temperature of the fixing device is equal to or lower than a predetermined temperature. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. 3. The dehumidifying control means turns on the dehumidifying heater while the drum temperature detecting element detects that the drum temperature of the photosensitive drum is below a predetermined temperature. The image forming apparatus according to claim 1. 4. A tray moving means for moving the paper feed tray up and down, and a weekly timer for changing the operating state of the image forming apparatus according to the arrival of a set time. After the transfer tray is lowered to separate the transfer sheet from the calling roller, the dehumidification control means confirms that the temperature detecting element used in the image forming apparatus has a temperature equal to or lower than a predetermined temperature. The image forming apparatus according to claim 1, wherein the dehumidifying heater is turned on during the detection. 5. The image forming apparatus according to claim 4, wherein the tray moving means has a configuration in which the lowered position of the paper feed tray can be selected stepwise.