JP3346974B2 - Optical system cooling device in image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling device used in an optical system of an image forming apparatus, and is applicable to, for example, an analog copying machine, a digital copying machine, a laser beam printer, and the like.

[0002]

2. Description of the Related Art An original is illuminated by an illumination lamp, an original image formed by an image forming optical system is formed on a photoconductive photosensitive member to form an electrostatic latent image, and the electrostatic latent image is developed. An image forming apparatus for providing an obtained visible image for image formation is widely known in connection with an analog copying machine, a digital copying machine, and the like.

As an illumination lamp for illuminating a document in such an image forming apparatus, generally, a halogen lamp or the like that generates high heat with light emission is used. The internal temperature of the image forming apparatus depends on the environmental temperature where the image forming apparatus is placed,
It tends to increase gradually under the influence of heat generation of the lighting lamp. As the internal temperature of the image forming apparatus rises, the temperature of the photoreceptor also rises with it, but the photoconductivity of the photoreceptor generally decreases with an increase in the temperature of the photoreceptor, and the photoconductive material is formed as the temperature of the photoreceptor increases. In general, the contrast (the potential difference between the image portion and the background portion) of an electrostatic latent image decreases.

For this reason, the cooling fan is usually used to cool the optical system in order to reduce the temperature rise inside the image forming apparatus due to the heat generated by the illumination lamp. Conventionally, as a method of cooling an optical system by a cooling fan, a “temperature control method” that controls a cooling fan so that the temperature near the optical system detected by a thermistor or the like is kept below a certain temperature.
Or, a "cooling efficiency switching method" in which the drive efficiency of the cooling fan is switched between standby and image formation, or a "control method by the number of image formations" in which cooling is performed only when the number of image forming processes exceeds a certain number. Various methods have been proposed, such as a "temperature prediction method" that predicts a rise in temperature from the amount of change in the amount of light of an illumination lamp and performs cooling when the predicted temperature becomes constant.

On the other hand, the cooling of the optical system by the cooling fan
Since cooling is performed by taking in cooling air from outside the image forming apparatus, fine dust taken in together with the cooling air inevitably adheres to the mirror surface and lens surface of the optical system. In addition, when the image forming apparatus is placed in an environment where a humidifier is used in winter, fine particles in which chlorine is adsorbed on the lime are generated, and the fine particles in which chlorine is adsorbed on the lime are taken into the image device. Then, it becomes a white fine powder and adheres to the mirror surface or lens surface of the optical system. As described above, when the fine dust and the fine powder adhere to the mirror surface and the lens surface of the optical system, the light transmission efficiency in the optical system is reduced, and an electrostatic latent image with high contrast cannot be formed.

[0006]

In order to prevent the entry of the fine dust and fine powder, a fine dust intrusion prevention filter, which is an antistatic filter, is provided in the outside air inflow path of the cooling fan to prevent such intrusion. However, although the fine dust intrusion prevention filter prevents the fine dust from entering, it lowers the cooling efficiency. Therefore, if the dirt is severe, the temperature inside the optical system cannot be increased even if the cooling fan is operated. Therefore, under the present circumstances, a service person regularly performs inspection, cleaning, and replacement work of the mirror surface and the lens surface of the optical system.

As described above, "dirt of optical system due to cooling"
In order to compensate for the deterioration of the electrostatic latent image forming function caused by the optical system, the amount of light emitted from the illumination lamp is increased according to the contamination of the optical system to compensate for the decrease in the imaging light reaching the photoconductor. I have.
However, the amount of heat generated also increases as the amount of light emitted from the illumination lamp increases. For example, in the above-described “temperature control method”, the amount of heat generated by the increase in the amount of light emitted from the illumination lamp increases the cooling time of the cooling fan. Or the cooling efficiency is reduced, and as a result, the amount of fine dust and fine particles taken in is increased, and this tends to spoil the tendency of the optical system to become dirty. At the same time, the antistatic filter becomes dirty, lowering the cooling efficiency, and eventually a vicious cycle is repeated.

Further, in the "cooling efficiency switching method" and the "control method based on the number of times of image formation", complicated control means is required to obtain an appropriate cooling effect when the light emission amount of the illumination lamp is changed. . Similarly, the “temperature prediction method” also requires a complicated circuit for predicting a temperature rise due to a change in light amount.

The present invention has been made to solve the above-mentioned problems of the prior art, and can sufficiently cool an optical system with a simple structure while preventing intrusion of fine dust and fine powder. It is an object to provide an optical system cooling device in an image forming apparatus.

[0010]

According to the first aspect of the present invention,
An original lamp is illuminated by an illumination lamp that changes the amount of light emission according to the applied voltage and generates heat by emitting light, and forms an electrostatic latent image by forming an original image on a photoconductive photoreceptor using an imaging optical system. and, an optical system cooling device for reducing the temperature rise due to heat generation of the illumination lamp in an image forming apparatus for subjecting the visible image obtained by developing the electrostatic latent image on the imaging, one or more A cooling fan and an anti-static filter in an outside air inflow path of the cooling fan, so that a temperature of the photoconductor is a predetermined value.
If the temperature is higher than the temperature, the electrostatic latent image forming characteristics of the photoconductor are detected.
The illumination based on the temperature of the photoconductor and the electrostatic latent image forming characteristics.
Adjust the voltage applied to the lamp and set the photoconductor temperature
If the temperature is lower than the temperature of
When the number of times has been reached, the electrostatic latent image forming characteristic of the photoconductor is detected.
And based on the temperature of the photoreceptor and the electrostatic latent image forming characteristics,
Adjusting and setting the applied voltage to the bright lamp
When the voltage is higher than the specified voltage, one or more cooling fans
It is characterized by being driven .

[0011] According to a second aspect of the invention, the cooling fan is provided two or more, depending on the application voltage to the illumination lamp, characterized in that changing the number of the cooling fan to be driven.

According to a third aspect of the present invention, there are provided two or more cooling fans, and when the voltage applied to the illumination lamp is equal to or more than a predetermined value or when the number of copies becomes equal to or more than a predetermined value. Each cooling fan is driven alternately in accordance with the increase of the applied voltage and the increase of the number of executions of the image forming process.

The invention according to claim 4 is characterized in that two cooling fans are provided.

The invention according to claim 5 is characterized in that the antistatic filter provided in the outside air inflow path of the cooling fan is individually provided for each cooling fan.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical system cooling device in an image forming apparatus according to the present invention will be described below with reference to the drawings. In FIG. 1, a contact glass 1 on which an original to be copied is placed is provided in an upper portion of the image forming apparatus. An illumination lamp 3 and a mirror 4 are arranged below the contact glass 1. The illumination lamp 3 and the mirror 4 are integrated, and
It can be moved in a horizontal direction (a direction parallel to the upper surface of the contact glass 1). The mirror 4 is inclined at 45 ° and reflects light reflected from the document in the horizontal direction.

In the reflected light path from the mirror 4, roof mirrors 5 and 5 'are provided so that their reflection surfaces are at 90.degree. And inclined at 45.degree. An imaging lens 6 is provided on the right side of the lower roof mirror 5 ′ in the horizontal direction.
On the right side of the lower roof mirror 5 'in the horizontal direction and on the right side of the imaging lens 6, the roof mirrors 7 and 7'
As in 5 ', the opposite faces are 90 ° from each other, and
It is provided at an angle of 45 °. On the left side of the roof mirror 7 ', a fixed mirror 8 is attached with the same inclination as that of the roof mirror 7 and with the reflection surfaces facing each other. further,
A window 9 is provided below the fixed mirror 8. Contact glass 1, illumination lamp 3, roof mirrors 5, 5 ', roof mirrors 7, 7', fixed mirror 8, window 9 as described above.
The optical system of the image forming apparatus is composed of such members.

A photosensitive drum 10 is provided below the window 9. An electrometer 12 is provided at the upper right of the outer peripheral side of the photoconductor drum 10, and a developing device 13 is provided on the outer peripheral side of the photoconductor drum 10 clockwise from the electrometer 12.
A belt-type transfer device 14, an electrometer 15, a cleaning unit 16, and a charging device 11 are provided. Further, a thermistor 25 is provided on the photosensitive drum as a temperature sensor.

Next, an image forming operation of the image forming apparatus will be described. First, when a document is placed on the contact glass 1 and a start key of an operation unit (not shown) is pressed, the illumination lamp 3 moves to the right in FIG.
The original is illuminated and scanned. 1/2 of the moving speed of the mirror 4
At this speed, the roof mirrors 5 and 5 'are also displaced to the right in the figure, and the reflected light flux from the original is reflected to the side by the mirror 4, turned back by the roof mirrors 5 and 5', and transmitted through the imaging lens 6, The light is folded back by the fixed roof mirrors 7 and 7 ′ and thereafter reflected downward by the fixed mirror 8. The light beam reflected by the fixed mirror 8 forms an original image on a photoconductive photosensitive drum 10 through a window 9 provided in a partition plate 24. The partition plate 24 is provided so that stray light from the exposure optical system side at the top of the apparatus does not reach the photoconductor 10 and that heat radiated from the illumination lamp 3 in the exposure optical system does not affect the photoconductor 10 as much as possible. Have been.

When the exposure is performed, the photosensitive drum 10 rotates clockwise at a constant speed, and is uniformly charged to a predetermined potential by the charging device 11. More specifically, the charging potential of the photoconductor is detected by the electrometer 12, and the charging device 11 is controlled so that the detected potential gives a predetermined potential. When the image of the document is irradiated from the window 9 onto the uniformly charged photoconductor 10, an electrostatic latent image corresponding to the document image is formed. This electrostatic latent image is developed by the phenomenon device 13 to become a visible image. This visible image is transferred to a transfer sheet S fed by a belt in a belt-type transfer device 14.
The transfer sheet S to which the visible image has been transferred is fixed with the visible image by a fixing device (not shown), and is discharged outside the device after the fixing.
The surface of the photosensitive drum 10 after the transfer is neutralized and cleaned by the cleaning unit 16.

Next, an optical system cooling device, which is a point of the present invention, will be described. 1 and 2, cooling fans 20 and 21 are attached to the optical system of the image forming apparatus. The cooling fans 20, 21 are provided on one side of the housing surrounding the optical system, and at a portion between the roof mirrors 5, 5 'and the roof mirrors 7, 7'. The cooling fans 20 and 21 are connected to a control unit 19 described later. Electrostatic filters 22 and 23 are mounted outside the cooling fans 20 and 21.

Further, a control unit 30 is incorporated in the image forming apparatus. The control unit 30 includes the control unit 19 and the power supply 1
8, the light source control device 17 and other members. The control unit 30 has a configuration in which a power source 18 and a control unit 19 are connected to the light source control device 17, and the power source 18 is connected to the illumination lamp 3. Further, the light source control device 17 includes a thermistor 25 provided on the photosensitive drum 10,
An electrometer 15 provided on the outer peripheral side of the photosensitive drum 10 is connected. Therefore, the electrometer 15 and the thermistor 25
Thereby, the electrostatic latent image forming characteristic of the photosensitive drum 10 is detected, and based on the detection, the light source control device 17 is configured to adjust and set the voltage applied to the illumination lamp 3.

The control means 19 is a control means for driving the cooling fan, and is connected to the cooling fans 20 and 21 as described above. The control means 19 and the light source control means 17
Can be specifically configured as a CPU (Central Processing Unit), a computer, or a control circuit, and can be assembled on the same board in terms of hardware. When the control means 19 activates the cooling fans 20 and 21, as shown in FIG.
Cooling air is taken into the optical system from outside the device via the electrostatic filters 22 and 23 and the cooling fans 20 and 21,
In addition, since the cooling air flows inside the optical system, an increase in the temperature of the illumination lamp 3 is suppressed.

Next, the detection of the electrostatic latent image forming characteristic and the adjustment setting of the voltage applied to the illumination lamp 3 by the light source control device 17 will be described. In FIG. 1, the photosensitive drum 10
Is detected when the image forming process is not performed. In this case, the photosensitive drum 10 is uniformly charged to a predetermined potential Vo by the charging device 11, and then the image of the reference pattern 2 is irradiated by the optical system. Note that the reference pattern 2 has a predetermined reference density.

The electrostatic latent image formed by the irradiation of the reference pattern 2 is moved without being developed, and
5 is detected as a reference background potential VL. The potential VL detected by the electrometer 15 is input to the light source control unit 17. In the light source control means 17, the potential difference ΔV,
ΔV = (Vo−VL) is calculated. Since the potential Vo is constant, the potential difference ΔV changes according to the potential VL. The smaller the potential difference ΔV, the worse the electrostatic latent image forming characteristics.

As described above, there are two main causes of the deterioration of the electrostatic latent image forming characteristics. One is dirt on a mirror surface or a lens surface in the optical system, and the other is a decrease in photoconductive characteristics due to a rise in the temperature of the photosensitive drum 10. Therefore, the light source control device 17 includes the thermistor 25 together with the potential VL.
Is input. The light source control device 17 determines in advance a table of applied voltages to be applied to the illumination lamp in order to form an appropriate electrostatic latent image in the present situation, or sets the applied voltage to light in accordance with the photoconductor temperature T and the potential difference ΔV. Body temperature T and potential difference Δ
An arithmetic expression for calculating based on V is stored, and an appropriate applied voltage V is determined based on input values of the photoconductor temperature T and the potential difference ΔV. Then, the determined applied voltage V
Is set to the power supply 18 and the imprint voltage of the illumination lamp 3 is adjusted. The power supply 18 may be a DC power supply or an AC power supply. The above is the adjustment setting of the voltage applied to the illumination lamp 3.

Next, the flow of the adjustment setting will be described. 3, when the power is turned on, the temperature T of the photoconductor 10 is detected by the thermistor 25, and this temperature T
Is compared with a preset temperature t (the temperature at which substantial degradation of the photoconductive properties starts). When the condition of T ≧ t is satisfied, the electrostatic latent image forming characteristic is detected, and the adjustment setting of the voltage applied to the illumination lamp 3 is performed. Lighting lamp 3
When the adjustment setting of the applied voltage to the is completed. Jump to label A, which is the step immediately after power-on.

When T <t, it is determined whether or not the number N of times the image process has been executed (counted by the counter and reset to 0 when the applied voltage is newly adjusted and set) has reached 1000 times. Is done. This determination is made by the light source control device 17. When the condition of the number N = 1000 is satisfied, the electrostatic latent image forming characteristic is detected, and the adjustment setting of the voltage applied to the illumination lamp 3 is performed. When the adjustment setting of the voltage applied to the illumination lamp 3 is completed. Jump to label A, which is the step immediately after power-on.

When the number of times N ≠ 1000, the applied voltage adjusted and set last time is maintained, and the process jumps to the label A which is a step immediately after the power is turned on.

Next, the drive control of the cooling fans 20, 21 will be described. In FIG. 4, when the power of the image forming apparatus is turned on and the copy start key of the control unit is turned on to execute the image forming process, the voltage applied to the illumination lamp 3 is set to the power supply 18. Is applied from the light source control device 17 to the control unit 19.
Is input to In step S <b> 1, the control unit 19 compares a certain value v of a preset voltage with the input applied voltage V.

If V <v, the amount of light emitted from the illumination lamp 3 is relatively small and the amount of heat generated is small (v is set in advance so as to satisfy such conditions). , 21 are not driven, that is, the cooling fan is turned off.
And start copying.

When the control means 19 compares a certain value v of a preset voltage with the input voltage V, V
If ≧ v is satisfied, the control unit 19 and the cooling fans 20 and 21 are driven because the amount of light emitted from the illumination lamp 3 is large. Thereafter, the copy operation is started.

As shown in FIG. 5, two applied voltage values v and w (w> v) are set in advance in the control means 19, and after passing through an applied voltage adjustment setting routine, the input voltage V is set.
Satisfies w> V ≧ v, one cooling fan 20 may be driven, and when V ≧ w through w> V, both cooling fans 20 and 21 may be driven together.
By doing so, it is possible to perform cooling more in accordance with the amount of heat generated by the illumination lamp 3.

Alternatively, in the case where the predetermined value of the preset voltage is only v, and in the case where there are two values of v and w, the input voltage V
However, when the input voltage V exceeds a preset applied voltage value v, the rotation speed of the cooling fans 20 and 21 may be increased stepwise or continuously as the input voltage V increases. This makes it possible to cool the illumination lamp 3 in accordance with the heating power.

According to the optical system cooling device in the image forming apparatus as described above, the at least one cooling fan 20, 21 and the antistatic filters 22, 23 in the outside air inflow path of the cooling fan 20, 21 are provided. The temperature T of the photoconductor is higher than the temperature t.
At this time, the background potential VL of the photoconductor is detected, and the temperature of the photoconductor is detected.
Voltage applied to the illumination lamp based on T and background potential VL
When V is adjusted and set, and the temperature T of the photoconductor is lower than the temperature t
Indicates that the number N of times of execution of the image forming process has reached 1000
At this time, the background potential VL of the photoconductor is detected and the temperature T of the photoconductor is detected.
And the background potential VL, the applied voltage V to the illumination lamp
A light source control unit 17 for adjusting setting the applied voltage V is a voltage
v since it has a control means 19 for driving one or more cooling fans 20, 21 when it becomes more than, with Shi to form a proper electrostatic latent image on the photosensitive drum 1 0 photoconductive lighting lamps Cooling fans 20, 21 only when the heat generation of 3 becomes constant
Is driven, and appropriate cooling according to heat generation of the illumination lamp 3 can be performed. Further, the driving of the cooling fan can be minimized, which leads to wasteful energy consumption and simplification of the device.

Two cooling fans 20 and 21 are provided so that the voltage applied to the illumination lamp 3 is equal to or greater than a predetermined value.
Alternatively, when the number of copies becomes equal to or more than a predetermined value, the cooling fans 20 and 21 are alternately driven in accordance with an increase in the applied voltage and an increase in the number of times the image forming process is performed. Since the cooling fans 20 and 21 are driven in response to the increase in the number of times the image forming process is performed, it is possible to prevent unidirectional contamination of the antistatic filter.

[0036]

According to the present invention, at least one cooling fan and an antistatic filter are provided in an outside air inflow path of the cooling fan .
Detects the electrostatic latent image forming characteristics and determines the temperature of the photoconductor and the electrostatic latent image
Adjust the voltage applied to the lighting lamp based on the characteristics
When the temperature of the photoconductor is lower than a predetermined temperature,
When the number of process executions reaches a predetermined number, the photosensitive member
Of the photoreceptor and the electrostatic latent image
Adjust the voltage applied to the illumination lamp based on the forming characteristics.
Because it has a light source control device for constant, a control means for driving the one or more cooling fans when the applied voltage becomes <br/> on Ne以with predetermined, proper to the photosensitive drum photoconductive Since the cooling fan is driven only when the heat generation of the illumination lamp is constant while forming an electrostatic latent image, appropriate cooling according to the heat generation of the illumination lamp can be performed. In addition, the driving of the cooling fan can be minimized, so that unnecessary energy consumption can be suppressed and the device can be simplified.

Further, two or more cooling fans are provided so that the voltage applied to the illumination lamp is equal to or higher than a predetermined value.
Alternatively, when the number of copies becomes equal to or greater than a predetermined value, the cooling fans are alternately driven in accordance with an increase in the applied voltage and an increase in the number of times the image forming process is performed. The drive is performed in response to an increase in the number of times the image forming process is performed, so that it is possible to prevent unidirectional contamination of the antistatic filter.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an embodiment of an optical system cooling device in an image forming apparatus according to the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a flowchart showing adjustment settings of a voltage applied to an illumination lamp in the image forming apparatus.

FIG. 4 is a flowchart showing drive control of a cooling fan in the image forming apparatus.

FIG. 5 is a flowchart showing another example of drive control of the cooling fan in the image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 3 Illumination lamp 10 Photoconductor 20 Cooling fan 21 Cooling fan 22 Antistatic filter 23 Antistatic filter

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-257776 (JP, A) JP-A-4-3082 (JP, A) JP-A-2-6977 (JP, A) JP-A-63-257 159873 (JP, A) JP-A-7-248654 (JP, A) JP-A-8-63083 (JP, A) JP-A-58-49966 (JP, A) JP-A-3-50567 (JP, A) JP-A-58-118663 (JP, A) JP-A-6-51600 (JP, A) JP-A-60-211474 (JP, A) Japanese Utility Model Application Sho 61-203755 (JP, U) (58) (Int.Cl. ⁷ , DB name) G03G 15/00 G03G 15/04-15/043 G03G 21/00 G03G 21/20

Claims (5)

(57) [Claims] 1. An original document is illuminated by an illumination lamp whose light emission amount changes in accordance with an applied voltage and generates heat by light emission, and an image of an original by an image forming optical system is formed on a photoconductive photoreceptor so as to be static. forming a latent image, there by the optical system cooling device for reducing the temperature rise due to heat generation of the illumination lamp in an image forming apparatus for subjecting the visible image to an image forming obtained by developing the electrostatic latent image And at least one cooling fan and an antistatic filter in an outside air inflow path of the cooling fan, and when the temperature of the photoconductor is higher than a predetermined temperature,
Detects the electrostatic latent image forming characteristics and determines the temperature of the photoconductor and the electrostatic latent image
Adjust the voltage applied to the lighting lamp based on the characteristics
When the temperature of the photoconductor is lower than the predetermined temperature, the image is set.
When the number of executions of the forming process reaches a predetermined number,
Detects the electrostatic latent image forming characteristics of the photoconductor,
Based on the latent image forming characteristics, the voltage applied to the illumination lamp
When the applied voltage set above is equal to or higher than a predetermined voltage,
An optical system cooling device in an image forming apparatus, wherein one or more cooling fans are driven . Wherein provided above the cooling fan or two, depending on the application voltage to the illumination lamp, an image forming apparatus according to claim 1, characterized in that changing the number of the cooling fan driven Optical system cooling device. 3. The cooling fan according to claim 1, wherein at least two cooling fans are provided, and when the applied voltage to the illumination lamp is equal to or more than a predetermined value or the number of copies is equal to or more than a predetermined value, the applied voltage is increased. 3. The optical system cooling device according to claim 1, wherein each of the cooling fans is driven alternately in accordance with a stepwise increase in the number of times the image forming process is performed. 4. The optical system cooling device in an image forming apparatus according to claim 2, wherein two cooling fans are provided. 5. The antistatic filter provided in the outside air inlet path of the cooling fan, the serial to any one of claims 1 to 4, characterized in that provided separately for each fan <br / > Optical system cooling device in the above image forming apparatus.