JPH103249A - Electrophotographic copying machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize control in accordance with the state of a machine and to prevent an optical system from being soiled by varying the cooling ratio of the inside of an optical system unit to the inside of an image forming unit. SOLUTION: As for a cooling means 30 for cooling the inside of the optical system unit 10 and the inside of the image forming unit 20; air inside the unit 10 is exhausted by the rotation by itself. The machine is provided with a cooling fan 31 exhausting the air inside the unit 20. By the rotation of the fan 31, the air inside the unit 10 and the air inside the unit 20 are discharged to the outside of the machine. The machine is provided with a control means to very the cooling rate between the inside of the unit 10 and the inside of the unit 20. As the control means, it is provided with an opening/closing member 41 capable of varying the cross section communicating an optical system exhaust path 32 and set at the middle of the path 32 communicating the unit 10 and the fan 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical unit having a scanning optical system for reading a document image by moving relative to a document, and for visualizing an image read by the scanning optical system on a transfer paper. The present invention relates to an electrophotographic copying machine having an image forming unit.

[0002]

2. Description of the Related Art An electrophotographic copying machine has various heat sources such as a heating element of a fixing device for fixing a toner image and a light source of a scanning optical system for reading a document. When the temperature inside the machine rises, each mechanism inside the machine is heated, which may cause a failure or accelerate deterioration. Therefore, in the conventional electrophotographic copying machine, in order to eliminate this fear, a cooling fan is provided to lower the temperature inside the copying machine.

In this type of electrophotographic copying machine, as disclosed in JP-A-54-91332 and JP-A-58-16254, in order to save power and reduce noise,
The number of revolutions of the cooling fan is controlled in accordance with the temperature inside the main body, and the number of revolutions of the cooling fan is set to be lower than during the copying operation during standby (idling) as seen in Japanese Utility Model Laid-Open Publication No. Sho 59-114563. Has been proposed.

[0004]

In an electrophotographic copying machine, image defects such as fog, reduction of Dmax, and image unevenness due to dirt on an optical system occur chronically as the period of use increases. I have. This is because
In the past, it was thought that toner contamination on the optical mirror and lens due to scattering of toner from the image forming unit was caused.However, when an electrophotographic copying machine equipped with a cooling means as a cooling fan was installed in the market, Unexpected toner contamination occurred during the endurance test during development. Therefore, as a result of diligent studies, the copying machine installed in the market has a much longer standby (idling) time than the copying machine tested during development. Therefore, the contamination of the optical system is caused not only by toner scattering from the image forming unit, but also by the driving of the cooling fan during standby, dust and the like flowing from a gap between the exterior and the original glass, etc. Have been found to be caused by sticking to lenses and lenses. Also, even during copying, the same result is obtained when the air is exhausted from the optical system more than necessary (prevention of temperature rise).

Accordingly, an object of the present invention is to propose an electrophotographic copying machine in which image defects such as fog, reduction in Dmax, and image unevenness due to contamination of an optical system are less likely to occur.

[0006]

The above object is achieved by the following constitution.

(1) An optical system unit provided with a scanning optical system for reading an image of a document while relatively moving with respect to the document, and an image forming unit for visualizing an image read by the scanning optical system on transfer paper. In an electrophotographic copier equipped with
Cooling means for cooling the inside of the optical system unit and the inside of the image forming unit, and control means for controlling a cooling ratio of the optical system unit to the inside of the image forming unit by the cooling means to be variable, An electrophotographic copying machine comprising:

(2) The cooling means includes a cooling fan,
By exhausting the inside of the optical system unit and the inside of the image forming unit along with the driving of the cooling fan, the inside of the optical system unit and the inside of the image forming unit can be cooled (1). Electrophotographic copier.

(3) The control means includes an opening / closing member that can open and close the optical system exhaust path in an optical system exhaust path that connects the cooling fan and the optical system unit, and opens and closes the opening and closing member. The electrophotographic copying machine according to (2), wherein the rejection ratio is variable.

(4) The electrophotographic copying machine according to (3), wherein the opening / closing member is also used as a lens base on which a lens is mounted and movable by zooming.

(5) The electrophotographic copying machine according to any one of (1) to (4), wherein the control means changes a cooling ratio in accordance with an operation state of the electrophotographic copying machine. Machine.

(6) The electrophotographic copying machine according to (5), wherein the control means controls the cooling ratio at idling to be smaller than the cooling ratio at copying operation.

(7) The control means makes the cooling ratio variable in conjunction with a motor for driving the scanning optical system or a motor for driving a driving member in the image forming unit. Any one of (1) to (6)
Electrophotographic copiers.

(8) The electrophotographic copying apparatus according to any one of (1) to (6), wherein the control means changes a cooling ratio in conjunction with a driving member in the scanning optical system. Machine.

(9) Optical system temperature detecting means for detecting the temperature in the optical system unit, and image forming temperature detecting means for detecting the temperature in the image forming unit, wherein the control means The cooling ratio is changed based on the temperature in the optical system unit detected by the optical system temperature detecting unit and / or the temperature in the image forming unit detected by the image forming temperature detecting unit. (1) An electrophotographic copying machine according to any one of (1) to (4).

(10) The control means changes a cooling ratio during a copying operation based on at least one of a sheet feeding size, a copying magnification, an exposure lamp voltage, and the number of copies during copying of the electrophotographic copying machine. (1) to (9)
Any one of the electrophotographic copying machines.

(11) An optical system unit having a scanning optical system for reading a document image by relatively moving with respect to a document, and an image forming unit for visualizing an image read by the scanning optical system on transfer paper. A motor for driving the scanning optical system or a motor for driving a driving member in the image forming unit, and exhausting air in the optical system unit using a motor as a driving source. An electrophotographic copying machine having a cooling fan for the same.

The "cooling ratio of the image forming unit in the optical system unit" (or simply referred to as "cooling ratio") in the present invention refers to the amount of air exhausted from the optical system unit per unit time. The amount is a numerator and the amount of air exhausted from the image forming unit is a denominator ratio.A small cooling ratio means that when the amount of air exhausted from the image forming unit is the same, the optical system The purpose is to reduce the amount of air exhausted from inside the unit.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram showing a first embodiment of an electrophotographic copying machine to which the present invention is applied.

The copying machine according to the present embodiment has an optical system unit 10 having a scanning optical system for reading a document image by moving relative to the document, and an image read by the scanning optical system is visualized on a transfer paper. And an image forming unit 20 to be formed. The copying machine shown in FIG. 1 is of a so-called analog type in which an image read by a scanning optical system is directly guided to the photosensitive drum 21. However, the present invention is not limited to this. Thereafter, a so-called digital type in which a latent image is formed on the photosensitive drum 21 by laser light or the like may be used.

The optical system unit 10 includes a platen 11 made of a transparent glass plate on which a document is placed, a platen cover 12 that covers the document placed on the platen 11, and a platen 12 placed on the platen 11. A first scanning base 13 that relatively moves with a document including an illumination lamp 131 that is a light source for irradiating the document with light and a first reflection mirror 132 that reflects light reflected by the illumination lamp 131 from the document; A second reflecting mirror 141 that reflects the light reflected by the first reflecting mirror 132 and a third reflecting mirror 142 that reflects the light reflected by the second reflecting mirror 141. A second scanning base 14 that moves at a speed, a lens unit 15 that forms an image of a document on a photosensitive drum 21 described later, and a fixed second unit that reflects light passing through the lens unit 15 to the photosensitive drum 21. 4 And a morphism mirror 16. Therefore, the image of the document on the document table 11 illuminated by the illumination lamp 131 includes the first reflection mirror 132, the second reflection mirror 141, the third reflection mirror 142, and the lens unit 1.
5, and an image is formed on the photosensitive drum 21 via the fourth reflection mirror 16. Then, the first scanning gantry 13 and the second scanning gantry 14 moving at half the speed of the first scanning gantry 13
Scans the entire surface of the original document that is stationary on the original table 11. Since the illumination lamp 131 emits light only when scanning a document, the illumination lamp 131 serves as a heat source during a copying operation.
The temperature in the optical system unit 10 rises.

The image forming unit 20 includes a photosensitive drum 21 having a photoconductive photosensitive layer as an image carrier that rotates clockwise in the figure, a charging unit 22 for uniformly charging the photosensitive drum 21, Photoreceptor drum 21 uniformly charged
Developing means 23 for developing the electrostatic latent image formed by exposing the image light from the above-described optical system unit 10 as a toner image, and transferring the toner image onto a separately conveyed transfer paper. A transfer / separation unit 24 for separating the photoconductor and the transfer paper; and a photoconductor drum 21 after transferring the toner image.
Cleaning means 25 for removing toner remaining on the top
And a fixing unit 26 that melts and fixes the toner image transferred onto the transfer paper by passing the transfer paper between the heating roller 261 and the pressure roller 262. The fixing unit 26 needs to maintain the temperature of the heating roller 261 for fusing and fixing the toner image at a predetermined temperature during the copying (copying) operation and at the time of the standby (idling), respectively. The heat source provided therein is controlled by a CPU (not shown). Therefore, the temperature inside the image forming unit 20 increases.

In the present embodiment, in order to cool the inside of the optical system unit 10 and the inside of the image forming unit 20, the cooling unit 30 is rotated by itself to form the optical system unit 1.
A cooling fan 31 is provided that exhausts the air inside the image forming unit 20 and also exhausts the air inside the image forming unit 20. Then, by the rotation of the cooling fan 31, the air in the optical system unit 10 and the air in the image forming unit 20 are separated.
Exhausted outside the machine.

The optical system unit 10 and the image forming unit 2
As a control means for changing a cooling ratio with respect to the inside of the optical system unit 0, a CPU and a driving means (not shown) are used to control the optical system unit 10
(In the present embodiment, the opening 33 of the optical system unit 10) in the middle of the optical system exhaust path 32 that communicates with the cooling fan 31.
Is provided with an opening / closing member 41 which can change the cross-sectional area with which the optical system exhaust path 32 communicates. That is,
By changing the cross-sectional area of the optical system exhaust path 32 by the opening / closing member 41, the ratio of the amount of air exhausted from the optical system unit to the amount of air exhausted from the image forming unit per unit time can be increased. Can be changed.

Therefore, compared with the conventional electrophotographic copying machine,
Since the cooling ratio can be made variable, control according to the state of the machine becomes possible, and contamination of the optical system can be prevented. As a result, image defects such as fogging, reduction of Dmax, and image unevenness occur. It becomes difficult.

In the present embodiment, the cooling ratio is changed between the copying machine and the idling operation of the copying machine. During idling, the cooling ratio of the optical system unit to the image forming unit is changed during the copying operation. (E.g., optical system / image formation = 0% / 100%), that is, by making the cross-sectional area of the optical system exhaust path 32 by the opening / closing member 41 smaller during idling than during the copying operation, conventionally. Cooling fan 3 when idling did not occur
It is possible to prevent dust and the like sucked from outside the apparatus by the driving of the first device from adhering to each member of the optical system.

This operation will be described with reference to the flow chart of the cooling means 30 and the control means in FIG. First, when the power of the copying machine is turned on in S1, initialization is performed in S2. At this time, the cooling fan 31 is set to the Lo rotation (for example, 1200 rpm), and the opening 33 is covered with the opening / closing member 41 so as to close the optical system exhaust path 32 so as to have a predetermined cooling ratio. The cooling ratio is set so that the exhaust by the fan 41 is almost entirely performed from the image forming unit 20. This state is maintained until the copying operation is started in S3. When the copying operation is started (S3), the cooling fan 31 is set to Hi rotation (for example, 2600 rpm), which is higher, and the cooling ratio of the optical system unit to the image forming unit is
The opening 33 is made larger than at the time of idling described above (for example, optical system / image formation = 50% / 50%).
The opening / closing member 41 which has been covered is slid by the drive means (not shown) to release the opening 33, and the cooling fan 31 is also evacuated from the optical system unit 10 to set a predetermined cooling ratio (S4). When the copying operation is completed in S5, that is, when the standby state (idling) state is started until the next copying operation is started, the cooling fan 31 is again turned to the Lo rotation (for example, 1200 rpm), which is a lower rotation point than during the copying operation. ), And the opening 33 is covered with the opening / closing member 41 so as to cover the optical system exhaust path 32 so that the cooling ratio during idling is maintained.
The cooling ratio is set so that the exhaust air is almost completely discharged from the image forming unit 20 (S6). Even if the opening / closing member 41 covers the opening, the cooling fan 31 may exhaust air from the inside of the optical system unit through another gap. However, since the amount of exhaust is small, it can be ignored. .

Further, in the present embodiment, an example has been shown in which the opening / closing member 41 is capable of opening and closing the opening 33 as the control means 40. However, in general, the lens unit 15 provided in the optical system unit 10 has a variable magnification. Since the lens is mounted on a plate-shaped lens base for moving at the time or the like, this lens base can be used in place of the opening / closing member. In this case, the driving means for moving at the time of zooming can also serve as the driving means for moving the opening / closing member 41, so that the cost can be reduced. The position where the opening 33 is provided is preferably provided outside the movable range of the lens base, and particularly preferably provided outside the movable range when performing variable-magnification copying.
The aperture 33 is no longer completely covered by the lens base when performing variable-magnification copying.
The exhaust within 0 can be sufficiently performed.

Further, in this embodiment, the switching of the cooling ratio, that is, the switching between the copying operation and the standby mode, is performed by the CPU which controls the sequence control of the copying machine main body (not shown). Image forming unit 2
A main motor (not shown) for rotating and driving the photosensitive drum 21 as a driving member in the optical unit 0, or an optical (not shown) for driving the first scanning frame 13 and / or the second scanning frame 14 as a scanning optical system. In this case, the cooling ratio can be changed by driving the opening / closing member 41 using the main motor or the optical motor as a driving source.

Further, the switching of the cooling ratio is performed by the first scanning base 1 which is a driven member in the optical system unit 10.
In conjunction with the third and / or second scanning gantry 14 (for example, based on a signal from a sensor that detects the home position of the scanning optical system, or directly interlocking with the movement of the scanning gantry via a cam or the like). The cooling ratio can be changed by driving the opening / closing member 41. In this case, in conjunction with the movement of the first scanning gantry 13 and / or the second scanning gantry, the opening / closing member 41 increases the cooling ratio.
Is moved so that the opening 33 is released.

Next, a second embodiment will be described with reference to FIG. The second embodiment can be applied to the electrophotographic copying machine described in the first embodiment. The electrophotographic copying machine includes an optical system temperature detecting unit for detecting the temperature in the optical system unit 10. The image forming unit 2 is disposed on or near the surface of the platen 11 (however, a non-image portion) or in the vicinity thereof.
An image forming temperature detecting means for detecting a temperature within 0 is disposed near the photosensitive drum 21, and the first embodiment is based on the temperatures detected by the optical system temperature detecting means and the image forming temperature detecting means. Opening and closing member 41
The cooling ratio is changed by controlling the area of the opening 33 due to the movement of.

FIG. 3 is a schematic diagram showing temperature changes of the optical system unit 10 and the image forming unit 20 according to the second embodiment. First, when the power of the copying machine is turned on, the temperature in the image forming unit 20 increases due to heat from the fixing unit 26, and the fixing unit 26 rises to a temperature at which copying can be performed. Thereafter, when the copying operation is started, the temperatures in the optical system unit 10 and the image forming unit 20 rise. The setting of the cooling ratio during the copying operation is performed based on the temperature in the optical system unit 10.
The cooling ratio is the same as in the idling state described later. This is the case where the temperature change shown in FIG. 3 is a case where continuous copying of 500 copies is performed. However, since the continuous copying is rarely performed, the temperature in the optical system unit 10 reaches T1. This is because the same as in the idling state is sufficient. As the continuous copying is continued, the temperature in the optical system unit 10 rises to T1 and T2, and the cooling rate is compared with that during idling according to the temperature rise, and the rate of cooling the optical system unit 10 is increased. Thereafter, when the copying operation is completed, the optical system unit 1
The cooling ratio is controlled based on the two temperatures inside 0 and inside the image forming unit 20. Table 1 shows the specific control of the cooling ratio.

[0034]

[Table 1]

In FIG. 3, the temperature in the image forming unit 20 has risen after the copying operation has been completed. This is because the rotation speed of the cooling fan is increased to H in a standby (idling) state.
However, the number of rotations of the cooling fan is set to Hi until a predetermined time elapses after continuous copying.
It may be maintained as it is.

In the above-described second embodiment, during the copying operation, the cooling ratio is controlled based on the temperature in the optical system unit 10. However, the present invention is not limited to this, and the cooling ratio is controlled based on the temperature in the image forming unit. Alternatively, the cooling ratio may be controlled based on two temperatures in the optical system unit 10 and the image forming unit 20. In the standby state, the cooling ratio is controlled based on the two temperatures in the optical system unit 10 and the image forming unit 20, but is not limited thereto.
The cooling ratio may be controlled based on any of the temperatures.

In each of the first and second embodiments described above, the paper feed size, the copy magnification, the voltage of the exposure lamp, and the number of copies are used to determine
By changing the cooling ratio during the copying operation, it is possible to perform cooling according to the copying conditions. Thus, generally, the optical system unit 1 during the copying operation is controlled by the copying conditions such as the sheet feeding size, the copying magnification, the voltage of the exposure lamp, and the number of copies.
Since the temperature rises within 0 are also different, even if the cooling rate is appropriate under certain copying conditions, the cooling rate will be excessive under other copying conditions, but it is optimal by changing the cooling rate according to the copying conditions. Cooling can be performed, and at the same time, dust and the like sucked in from outside the apparatus by driving the cooling fan 31 during the copying operation can be suppressed from adhering to each member of the optical system.

Next, a third embodiment of an electrophotographic copying machine to which the second invention is applied will be described with reference to FIG. In the third embodiment, the same means and members as in the first embodiment are denoted by the same reference numerals. In the third embodiment, an optical system cooling fan 34 for cooling (exhausting) the inside of the optical system unit 10 is provided.
The cooling fan 34 has a propeller or a fin, and a main motor (not shown) for rotationally driving the photosensitive drum 21 which is a driving member in the image forming unit 20, or a scanning optical system. An optical system motor (not shown) for driving the first scanning gantry 13 and / or the second scanning gantry 14 is a driving source. Since the main motor or the optical system motor operates only during the copying operation, the propeller or the fin of the optical system cooling fan 34 is rotated by using the main motor or the optical motor as a driving source, so that the temperature rise due to the heat generated from the illumination lamp 131 during the copying operation. In addition, since the propeller or the fin does not rotate in the standby (idling) state, dust or the like flowing from the gap during the standby can be suppressed, and the optical system is less likely to be stained. In addition, in the present embodiment, the main motor or the optical system motor which is originally required is used as a drive source for rotating the propeller or the fin of the optical system cooling fan 34, so that the configuration can be made very inexpensive.

In the third embodiment, a cooling fan 35 for cooling the inside of the image forming unit 20 is provided.
5 driven by a dedicated drive motor. Needless to say, the cooling fan 35 may also serve to cool a part of the optical system unit 10.

[0040]

According to the first aspect of the present invention, in an electrophotographic copying machine having a cooling means, the cooling ratio between the optical system unit and the image forming unit is made variable, whereby control according to the state of the machine is performed. This makes it possible to prevent the optical system from being stained, thereby providing an effect that image defects such as fog, reduction of Dmax, and image unevenness are less likely to occur.

In the second invention, since the drive source of the fan for cooling the optical system unit is a main motor or an optical system motor, the optical system unit can be cooled during the copying operation, and the optical system unit can be cooled during the standby state. This has the effect that dirt can be prevented and the configuration can be made at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of an electrophotographic copying machine to which the present invention is applied.

FIG. 2 is a flowchart of a cooling unit and a control unit.

FIG. 3 is a schematic diagram illustrating temperature changes of an optical system unit and an image forming unit according to a second embodiment.

FIG. 4 is a schematic configuration diagram showing a third embodiment of an electrophotographic copying machine to which the second invention is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Optical system unit 20 Image forming unit 30 Cooling means 31 Cooling fan 34 Optical system cooling fan 41 Opening / closing member

Claims (11)

[Claims] 1. An optical system unit comprising a scanning optical system for reading a document image by relatively moving with respect to a document, and an image forming unit for visualizing an image read by the scanning optical system on transfer paper. A cooling unit for cooling the optical system unit and the image forming unit; and a cooling ratio of the cooling unit to the image forming unit in the optical system unit. Control means for performing such control as described above. 2. The cooling unit includes a cooling fan, and the inside of the optical system unit and the inside of the image forming unit are evacuated by driving the cooling fan to exhaust the inside of the optical system unit and the inside of the image forming unit. 2. An electrophotographic copying machine according to claim 1, wherein cooling of said electrophotographic copying machine is enabled. 3. The control means includes an opening / closing member that can open and close the optical system exhaust path in an optical system exhaust path that connects the cooling fan and the optical system unit, and opens and closes the opening and closing member. 3. The electrophotographic copying machine according to claim 2, wherein the cooling ratio is variable. 4. An electrophotographic copying machine according to claim 3, wherein said opening / closing member is also used as a lens base on which a lens is mounted and movable by zooming. 5. The electrophotographic copying machine according to claim 1, wherein said control means changes a cooling ratio according to an operation state of said electrophotographic copying machine. . 6. The electrophotographic copying machine according to claim 5, wherein said control means controls the cooling ratio at idling to be smaller than the cooling ratio at copying operation. 7. The cooling unit according to claim 1, wherein the control unit changes a cooling ratio in conjunction with a motor for driving the scanning optical system or a motor for driving a driving member in the image forming unit. An electrophotographic copying machine according to claim 1. 8. The electrophotographic copying machine according to claim 1, wherein said control means changes a cooling ratio in conjunction with a driving member in said scanning optical system. . 9. An optical system temperature detecting means for detecting a temperature in the optical system unit; and an image forming temperature detecting means for detecting a temperature in the image forming unit, wherein the control means includes The cooling ratio is changed based on the temperature in the optical system unit detected by the system temperature detecting means and / or the temperature in the image forming unit detected by the image forming temperature detecting means. An electrophotographic copying machine according to claim 1. 10. The control means according to claim 1, wherein said electrophotographic copying machine has a paper feed size, a copy magnification, an exposure lamp voltage,
The electrophotographic copying machine according to any one of claims 1 to 9, wherein a cooling ratio during a copying operation is changed based on at least one of the number of copies. 11. An optical system unit having a scanning optical system for reading a document image by relatively moving with respect to a document, and an image forming unit for visualizing an image read by the scanning optical system on transfer paper. An electrophotographic copying machine provided with a motor for driving the scanning optical system or a motor for driving a driving member in the image forming unit for exhausting air in the optical system unit. An electrophotographic copying machine having a cooling fan.