JPH0683153A - Image forming device - Google Patents

Abstract

PURPOSE:To surely, usefully and efficiently control humidity in respective parts requiring the dehumidification in an electrophotographic process by a few dehumidifying means dehumidifying the inside of a device and to stabilize image quality by surely distributing and sending dehumidified air from the dehumidifying means to the respective parts by an air distributing and sending means. CONSTITUTION:The low-temperature dehumidified air 431 and the heated dehumidified air 432 corresponding to each element in the electrophotographic process are distributively sent to each element, and exhausted from the vicinity of each element. The environment of each element is set according to the conditions of the air 431 and the air 432 and the optimum characteristic of the electrophotographic process is obtained. Therefore, not only a start signal but also output from an outside temperature sensor 300 and other input are inputted in a CPU 500. Then, an operation signal for respective drivers 501 to 503 driving the Peltier element 403 and fans 409 and 410 of the dehumidifying means 400 and other output are fetched from the CPU 500.

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, and more particularly to an image forming apparatus by an electrophotographic process having a dehumidifying means for dehumidifying the inside of the apparatus.

[0002]

2. Description of the Related Art Humidity affects characteristics such as charging, exposure, development and transfer in an electrophotographic process, and makes image quality such as image density unstable.

Japanese Patent Laid-Open No. 52-134733 discloses
A humidity sensor detects the humidity of a specific part in the copying machine using the electrophotographic process, and the humidifying means is activated according to the output of the humidity sensor to adjust the specific part to a predetermined humidity, and the developer is dried by a desiccant. A technique for dehumidifying is disclosed.

As a result, it is possible to prevent the characteristics of the electrophotographic process in the specific portion from varying with humidity, and to prevent the characteristics of the developer from being affected by high humidity. Therefore, the image quality can be stabilized.

[0005]

By the way, many of the characteristics of the electrophotographic process are affected by humidity.

Therefore, just by controlling the humidity in two parts as in the conventional case, the characteristics of the electrophotographic process in many other parts are changed by the humidity, and the image quality cannot be sufficiently stabilized.

Further, if a separate humidity control means is provided for each part where humidity control is required, the structure becomes complicated and expensive. It is not practical to apply this to all parts that require humidity control.
It is more difficult to realize if the characteristic of the electrophotographic process depends on the temperature.

In view of the above points, the present invention can surely achieve the humidity control of each part requiring the humidity control with a small amount of dehumidifying means, and, if necessary, guarantee the temperature of each characteristic of the electrophotographic process. Another object is to provide an image forming apparatus which can be similarly achieved.

[0009]

In order to achieve the above object, the present invention provides an image forming apparatus by an electrophotographic process having a dehumidifying means for dehumidifying the inside of the apparatus, and dehumidified air dehumidified by the dehumidifying means. Is provided with a means for separately delivering air to each part of the electrophotographic process that requires dehumidification.

In this case, the dehumidifying means brings the low temperature portion of the refrigeration mechanism into contact with the air to be dehumidified, and after a part of the dehumidified air is brought into contact with the high temperature portion of the refrigeration mechanism, dehumidification and temperature guarantee of the electrophotographic process are performed. It is preferable to provide means for distributing air to necessary parts.

Further, it is more preferable that the refrigerating mechanism uses a Peltier element.

[0012]

According to the above-mentioned mechanism of the present invention, dehumidified air from the dehumidifying means for dehumidifying the inside of the apparatus is surely distributed and blown to each portion of the electrophotographic process which needs dehumidification by the partial distribution air blowing means. It is possible to surely control the humidity of No. 2 by a small amount of dehumidifying means.

If the dehumidifying means is a refrigeration mechanism, the dehumidification can be achieved by bringing the air to be dehumidified into contact with the low temperature portion thereof, and a part of the dehumidified air is brought into contact with the high temperature portion of the refrigeration mechanism. Dehumidification of these dehumidified and temperature-guaranteed parts is reduced even if the dehumidified temperature-elevated air can be partly-distributed to each part of the electrophotographic process that requires dehumidification and temperature guarantee by the minute distribution air means. The means can be shared and achieved.

If the refrigerating mechanism uses a Peltier element, the heat exchange section is directly provided in the low temperature section and the high temperature section of the Peltier element and the dehumidification and the temperature added thereto are guaranteed only by contacting with the air to be dehumidified. Can be achieved.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows the overall construction of the digital color copying machine of the first embodiment.

This digital color copying machine is roughly divided into an image reader section 100 for reading an original image and a copying section 200 for reproducing an image read by the image reader section 100.

In the image reader unit 100, the scanner 10 includes an exposure lamp 12 for irradiating an original, a rod lens array 13 for condensing reflected light from the original, and a contact type for converting the condensed light into an electric signal. The CCD color image sensor 14 of FIG. The scanner 10 is driven by the motor 11 at the time of reading an original, moves in the direction of the arrow (sub scanning direction), and scans the original placed on the platen 15. The image on the document surface illuminated by the exposure lamp 12 is photoelectrically converted by the image sensor 14.

R obtained by the image sensor 14,
The multi-valued electrical signals of G and B are converted into 8-bit gradation data of any one of yellow (Y), magenta (M), cyan (C), and black (K) by the read signal processing unit 20. It is converted and stored in the synchronization buffer memory 30.

Next, in the copying section 200, the print head section 31 performs gradation correction (γ correction) on the input gradation data according to the gradation characteristics of the photoconductor, and then the corrected image. Data is D / A converted to generate a laser diode drive signal, and the semiconductor laser is caused to emit light by this drive signal.

The print head unit 3 corresponding to the gradation data
The laser beam emitted from the laser beam No. 1 exposes the photosensitive drum 41, which is rotationally driven, via the reflecting mirror 37. The photoconductor drum 41 is cleaned of residual toner by the cleaner unit 40 before being exposed for each copy.
After being irradiated with the eraser lamp 42, the charging charger 4
3 is uniformly charged. When exposed in this state, an electrostatic latent image of the original is formed on the photosensitive drum 41. Only one of the cyan, magenta, yellow, and black toner developing devices 45a to 45d is selected to develop the electrostatic latent image on the photosensitive drum 41. The developed toner image is transferred by the transfer charger 46 onto the copy paper wound around the transfer drum 51.

After the four colors of copy paper have been transferred, the transfer drum 5
It is separated from 1 and sent to the fixing unit 60. Then, after the fixing process is performed here, the sheet is discharged to the tray 61. Reference numeral 62 is a paper feeding unit.

The developing units 45a to 45d are of an elevator type in which the developing units used are opposed to the photosensitive drum 41 so that development is performed with toner of a predetermined color.

The mechanism for raising and lowering and driving the same is shown in FIG. In FIG. 2, the driving means 120 is composed of a stepping motor 121 and a timing belt 127 stretched over sprockets 124 and 125.
Rails 112 provided on the outside of the frames 110, 110 for holding 5a to 45d are engaged with guide rails 116 fixed on the inside of the fixed frames 115, 115. As a result, the developing units 45a to 45d are movable in the vertical direction, and the brackets 113, 113 fixed to the outside of the frames 110, 110 are fixed to the fixed frames 115, 115.
From the guides 115a, 115a of the
It is fixed to the timing belt 127 via the metal fitting 114. The output gear 122 of the stepping motor 121 meshes with the gear 123, and the gear 123 is connected to the sprocket 125.
It is fixed to one end of a support shaft 126 that supports the. Spindle 1
The other end of 26 is extended to the outside of the fixed frame 115 at the back in FIG. 2, and another timing belt (not shown) is stretched.

The stepping motor 121 is rotationally driven by a drive circuit (not shown), and its rotational force is gears 122, 1
23, timing belt 1 through sprocket 125
27 and the developing devices 45a to 45d are integrally moved up and down as a unit. The position of each of the developing devices 45a to 45d is detected by a sensor (not shown), and by controlling the rotating plate of the stepping motor 121, an arbitrary developing device is stopped at a position facing the developing position.

A constant output spring 119 is installed on the fixed frames 115, 115.

The free end of the constant output spring 119 is fixed to the frames 110, 110 and constantly outputs a spring force equal to the total weight of the developing devices 45a to 45d to develop the developing devices 45a to 45d.
The d is lifted to reduce the driving force of the driving means 120.

By the way, the change of environmental humidity greatly affects the image formation by the electrophotographic process in the copying section 200.

For example, the characteristics such as the developing efficiency depend on the charge amount of the toner. The charge amount depends on the temperature and the humidity as shown in FIG. 6 and the relationship between the humidity and the toner charge amount in FIG.

As can be seen from the respective figures, the toner charge amount tends to be stable when the temperature and humidity are both low.

Therefore, it is desirable that the surroundings of the developing device are as low temperature and low humidity environment as possible.

The temperature and humidity also affect the characteristics of the photosensitive drum.

[0033] Generally, in a high-humidity conditions, fluctuations in the residual potential as shown in FIG. 8 in the image forming repeatedly (V _R), is to become elements often unstable characteristic of the photosensitive member.

Therefore, in order to stabilize the characteristics of the photosensitive drum, it is necessary to devise so that the surrounding environment is not in a high humidity state.

Further, the sensitivity of the photosensitive drum depends on the temperature as shown in FIG. 9, and the higher the temperature, the higher the sensitivity.

In order to increase the sensitivity, as a means for warming the photosensitive drum, a device such as mounting a drum heater inside the photosensitive drum has been conventionally devised.

On the other hand, the transfer efficiency of the toner from the photosensitive drum to the copy paper depends on the surface resistance of the copy paper, and the surface resistance of the copy paper is determined by the water content in the copy paper. Therefore, it is affected by environmental humidity.

FIG. 10 shows the relationship between the surface resistance of the copy paper and the transfer efficiency, and FIG. 11 shows the relationship between the water content and the surface resistance of the copy paper.

As can be seen from FIG. 10, the higher the surface resistance of the copy paper, the higher the transfer efficiency, and the more stable the transfer efficiency becomes.

From FIG. 11, the surface resistance of the copy paper increases as the water content decreases.

Further, in the image reader section 100, the temperature tends to increase as the lamp 12 is turned on during reading.
Higher temperatures have adverse effects such as sensitivity fluctuations of spectral filters for color copying.

In general, in order to prevent the temperature from rising, warmed air is exhausted by a fan or the like.

As described above, in order to stabilize the characteristics of the developer (toner charge amount), the surroundings of the developing devices 45a to 45d are kept in a low temperature and low humidity environment, and in the case of the photoconductor, the sensitivity is increased to stabilize the characteristics. In order to do so, it is desirable to make the surroundings a high temperature and low humidity environment.

As is typical of these, even in the same copying machine, the desired environment differs depending on the elements.

Although it is conceivable to use a plurality of means for each part as in the prior art in order to make each element a desired environment, this is not desirable in terms of cost and space efficiency in the machine.

Therefore, a dehumidifying means 400 is provided which can obtain different environments by one means without using a plurality of means.

For this reason, the dehumidifying means 400 adopts a refrigerating mechanism and skillfully utilizes the low temperature part and the high temperature part thereof. Specifically, as shown in FIG. 3, a Peltier element 403 which is a refrigerating element is used. However, it is not limited to this.

The Peltier element 403 has a P / N junction portion 40.
3a has a low temperature part 403b and a high temperature part 403c on both sides,
The cooling fin 405 and the heat radiation fin 406 are separately coupled to the low temperature portion 403b and the high temperature portion 403c.

The low temperature section 403b is located in the dehumidifying chamber 406 where the air in the copying section 200 is introduced from the lower suction port 411 by the fan 405, and the high temperature section 403c communicates with the dehumidifying chamber 406 in the upper communicating path 407. It is located in the heating chamber 408.

A fan 409 is provided above the dehumidifying chamber 406, and the dehumidified air in the dehumidifying chamber 406 is discharged from the exhaust port 412.

An exhaust port 413 is provided in the lower part of the heating chamber 408 so that the fan 410 discharges the dehumidified air after heating.

At the lower part of the dehumidifying chamber 406, the recovered water receiving section 41 is provided.
4 are formed.

The low temperature dehumidified air 431 discharged from the exhaust port 412 is distributed by the distribution air duct 421 around the image reader unit 100 and the developing devices 45a to 45d, and is discharged from the exhaust port 413. Heating and dehumidifying air 4
32 is configured so as to distribute air around the photosensitive drum 41 and around the copy paper accommodating portion 62a of the paper feeding portion 62 by the minute distribution air duct 422.

The dehumidified air 431 sent to the periphery of the developing units 45a to 45d is then exhausted from the rear surface to the outside of the machine by the exhaust fan 441.

The dehumidified air 431 sent to the image reader unit 100 is exhausted by the exhaust fan 443 while cooling the lamp 12, the electronic circuit board and the like by the blower fan 442.

The humidifying / dehumidifying air 432 sent to the periphery of the photosensitive drum 41 is then exhausted from the rear surface to the outside of the machine by the exhaust fan 444. Further, the heated and dehumidified air sent to the periphery of the copy paper storage portion 62a of the paper feed portion 62 is exhausted outside the machine by the exhaust fan 445.

As described above, the low temperature humidified air 431 and the warmed dehumidified air 432 corresponding to the respective elements of the electrophotographic process are separately delivered, and these elements are exhausted from the vicinity of the respective elements. The environment of the element can be set according to the conditions of the low temperature dehumidified air 431 and the warmed dehumidified air 432, and optimum characteristics of the electrophotographic process can be obtained.

In this embodiment, as shown in FIG.
The CPU 500 for controlling the operation of the copying machine shown in FIG.

Therefore, the CPU 500 receives the output of the temperature sensor 300 and other inputs in addition to the start signal. Further, the drivers 501 to 5 for driving the Peltier element 403 and the fans 409 and 410 of the dehumidifying means 400.
The operation signal 03 and other outputs are output.

FIG. 5 is a flow chart showing the main contents of the humidity adjustment control by the control circuit of FIG.

First, when the humidity in the copying machine is higher than 70% RH, it is expected that all the materials such as the developer, the photosensitive drum 41 and the copy paper will be adversely affected. Therefore, the fan 409 that sends the low temperature dehumidified air 431 and the warmed dehumidified air 4
The fan 410 for sending 32 is operated together to supply respective air to each element.

Even if the temperature is 70% or less, the developing device 45
If the temperature T ₁ around a to 45d is higher than 30 ° C, it is determined that the developer is adversely affected, and the low temperature dehumidified air 4
31 to drive the fan 409 to send the developing device 45a to 45d
Cool the surroundings.

Further, when the temperature T ₂ around the photosensitive drum 41 is lower than 10 ° C., it is determined that the sensitivity of the photosensitive drum 41 is lowered, and the fan 41 sending the heated dehumidified air 432 is sent.
0 is driven to warm the photosensitive drum 41.

FIG. 12 shows a second embodiment of the present invention, in which the developing devices 45a to 45d are housed in a casing 600.

In order to dehumidify more efficiently, a casing 600 having a size that covers a space required for moving the movable developing units 45a to 45d is provided in order to make a target space as small as possible. The low-temperature dehumidified air 431 from the dehumidifying means 400 is directly supplied into this through the distribution air duct 421. Then, the fan 601 exhausts the air to the outside of the machine.

By this method, the developing devices 45a to 45d
The peripheral dehumidification can be performed more efficiently.

The other structure is the same as that of the first embodiment.

FIG. 13 shows a third embodiment of the present invention in which the casing 600 of the developing devices 45a to 45d is movable.

Therefore, the casing 600 is the developing unit 45.
Instead of making it according to the moving space of a-45d,
The minimum size required to wrap the developing units 45a to 45d is set, and the developing units 45a to 45d themselves can be moved.

As a result, the space around the developing units 45a to 45d to be dehumidified can be reduced to the necessary minimum, and the dehumidification efficiency is further improved.

The portion of the separate delivery air duct 421 that is in contact with the casing 600 is a telescopic portion 421a so as not to obstruct the movement of the casing 600.

The exhaust pipe 611, which is in contact with the upper part of the casing 600, is also expandable and contractable for the same reason.

The other structure is the same as that of the second embodiment.

FIG. 14 shows a fourth embodiment of the present invention, which is a modification of the second embodiment.

Low temperature dehumidified air 431 from dehumidifying means 400
Are all fed into a fixed casing 600, and are distributed and supplied to the photosensitive drum 41 from an opening 631 provided in the casing 600 so as to face the photosensitive drum 41. The casing 600 also forms a part of the minute distribution air duct 421. is there.

A shutter 632 is provided in the opening 631 so that it can be opened and closed as appropriate.

This shutter 632 is opened only during development,
Other than that, the operation of closing is performed. As a result, the low temperature dehumidifying air 431 supplied from the dehumidifying means 400 is all supplied to the developing devices 45a to 45d through the casing 600, and the developing devices 45a to 45d at the time of development can be efficiently dehumidified.

The other structure is the same as that of the second embodiment.

FIGS. 15 and 16 show a fifth embodiment of the present invention, in which developing devices 45a to 45 used in a rotary type are used.
The case of an analog color copying machine having 5d is shown.

This copying machine has an analog exposure optical system 700 which replaces the digital exposure optical system of the copying machines of the above-mentioned respective embodiments.

In FIG. 15, a rotary developing unit 70 in which developing devices 45a to 45d are arranged around the rotation center.
A blower pipe 702 as shown in FIG. 14 is provided at the center of 1,
The low temperature dehumidified air 431 from the dehumidifying means 400 is supplied to this through the duct 421.

As shown in FIG. 16, the blower pipe 702 has a blower port 703 facing the developing devices 45a to 45d,
The supplied low temperature dehumidified air 431 is supplied to each of the developing devices 45a to 45a.
Blow to d to dehumidify them.

At this time, the dehumidification efficiency is further improved by providing a casing for covering the developing unit 700 as in the second and fourth embodiments, or by providing a shutter at a portion of the casing facing the photosensitive drum 41. You can also

It is also possible to provide two or more dehumidifying means depending on the type of the dehumidifying target portion, and to separately deliver air to a plurality of portions from each of them.

[0085]

According to the present invention, the dehumidified air from the dehumidifying means for dehumidifying the inside of the apparatus is surely distributed and blown to each portion of the electrophotographic process requiring dehumidification by the partial delivery air means. It is possible to stabilize the image quality by reliably and efficiently controlling the humidity by the dehumidifying means with little humidity control.

In addition to using the refrigeration mechanism as the dehumidifying means to directly deliver the dehumidified air dehumidified in the low temperature section to the specific section, a part of the dehumidified air is heated in the high temperature section to obtain heated dehumidified air. , By separately distributing the air to other specific parts, the dehumidification-only process and the dehumidification with temperature guarantee, which meet the optimum conditions for each part of the electrophotographic process, are individually achieved by one dehumidifying means. Therefore, the image quality can be further stabilized without making the structure particularly complicated.

Further, when the refrigerating mechanism uses a Peltier element, the heat exchange section is directly provided in the low temperature section and the high temperature section of the Peltier element, and the dehumidification and the temperature applied thereto are simply contacted with the air to be dehumidified. The guarantee can be achieved, the structure is simple, small and inexpensive, and the feature that it is silent is also exhibited. Moreover, since the high temperature portion is cooled by contact with the dehumidified air, the dehumidification efficiency of the low temperature portion is significantly improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a digital color copying machine showing a first embodiment of the present invention.

FIG. 2 is a perspective view showing an elevating mechanism of a developing device of the copying machine of FIG.

FIG. 3 is a sectional view of a dehumidifying means.

FIG. 4 is a block diagram of a control circuit of the copying machine of FIG.

5 is a flowchart showing the contents of operation control relating to dehumidification by the control circuit of FIG.

FIG. 6 is a graph showing the relationship between temperature and toner charge amount.

FIG. 7 is a graph showing a relationship between humidity and toner charge amount.

FIG. 8 is a graph showing the relationship between the exposure amount and the residual potential, which shows the effect of humidity on the characteristics of the photoconductor.

FIG. 9 is a graph showing the relationship between the exposure amount and the residual potential, which shows the effect of temperature on the photoreceptor characteristics.

FIG. 10 is a graph showing the relationship between the surface resistance of copy paper and the transfer efficiency.

FIG. 11 is a graph showing the relationship between the water content of copy paper and the surface resistance.

FIG. 12 is an overall configuration diagram of a digital color copying machine showing a second embodiment of the present invention.

FIG. 13 is an overall configuration diagram of a digital color copying machine showing a third embodiment of the present invention.

FIG. 14 is an overall configuration diagram of a digital color copying machine showing a fourth embodiment of the present invention.

FIG. 15 is an overall configuration diagram of an analog color copying machine showing a fifth embodiment of the present invention.

FIG. 16 is a perspective view of a blower tube.

[Explanation of symbols]

 100 image reader unit 200 copying unit 300 humidity sensor 400 dehumidifying unit 403 Peltier element 403b low temperature unit 403c high temperature unit 406 dehumidification chamber 408 heating greenhouse 409, 410 fan 421, 422 minutes delivery air duct 702 air duct 41 photoconductor drum 45a to 45d development Container 62a Copy paper storage unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideo Kitakubo Hideo Kitakubo 2-13-13 Azuchi-cho, Chuo-ku, Osaka City, Osaka Prefecture Minato Camera Co., Ltd. (72) Hideaki Kodama Azuchi, Chuo-ku, Osaka City, Osaka Prefecture 2-3-3 Machi Osaka International Building Minolta Camera Co., Ltd.

Claims (3)

[Claims] 1. An image forming apparatus using an electrophotographic process, which comprises a dehumidifying means for dehumidifying the inside of the apparatus, and means for separately delivering the dehumidified air dehumidified by the dehumidifying means to each part of the electrophotographic process requiring dehumidification. An image forming apparatus characterized by being provided. 2. The dehumidifying means is for bringing the air to be dehumidified into contact with the low temperature part of the refrigeration mechanism, and dehumidification and temperature guarantee of the electrophotographic process are required after a part of the dehumidified air is contacted with the high temperature part of the refrigeration mechanism The image forming apparatus according to claim 1, further comprising a unit for distributing and delivering air to each unit. 3. The image forming apparatus according to claim 2, wherein the refrigerating mechanism uses a Peltier element.