JPH08304938A - Optical unit for copying machine - Google Patents

Abstract

PURPOSE: To provide an inexpensive optical unit for a copying machine having simple constitution and capable of restraining temperature rise caused by an exposing lamp and the staining of a mirror or a lens to the minimum without setting a thermistor in the vicinity of a contact glass. CONSTITUTION: This optical unit for a copying machine is provided with the contact glass, the exposing lamp for exposing an original on the contact glass, a mirror and a lens for guiding reflected light from the original to a photoreceptor 12, and an exposing lamp cooling fan; and a temperature detecting means 21 is set in the vicinity of the photoreceptor 12 and the driving of the cooling fan is decided according to whether the driving of a copying machine main body is on or off and whether the detected result of the detecting means 21 attains set temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical unit of a copying machine equipped with a cooling fan for suppressing a temperature rise due to an exposure lamp for illuminating a document.

[0002]

2. Description of the Related Art In an optical unit of a copying machine, an exposure lamp for reading a document is indispensable, and a halogen lamp is generally used as the exposure lamp in view of its size, cost, light amount, and the like. Most used However, the halogen lamp has a large amount of heat generation, and when the copying operation is continuously performed, the temperature inside the contact glass and the optical unit rises, which adversely affects the parts inside the unit and the user is burned. Since a problem may occur, most optical units are provided with cooling fans for forced air cooling. on the other hand,
In this optical unit, a mirror, a lens, etc. are arranged, and dust or dust in the air is carried by the air blown by the cooling fan, and if they adhere, density unevenness or the like occurs in the formed copy image, The optimum image may not be obtained. Therefore, in order to solve the above two problems, in a recent copying machine, as shown in FIG. 8, a thermistor 5 is installed in the vicinity of the contact glass 6, and its output exceeds a preset temperature. Only in this case, the cooling fan 4 is turned on, and the sucked outside air flows in the direction of the arrow, passes through the portion of the halogen lamp 1, and is exhausted. (In the figure, 2 is the first scanner,
Reference numeral 3 is a second scanner. ) By adopting this method, the contamination of the mirror and the lens can be reduced and the temperature rise can be prevented.

[0003]

However, in the optical unit of the conventional copying machine described above, the thermistor 5 must be installed near the contact glass 6, so that the cost of the thermistor 5 is extra and space is limited. However, there was a problem that it could not be installed on a small machine with little room. Therefore, the present invention solves the above-mentioned conventional problems and can minimize the temperature rise of the exposure lamp and the contamination of the mirror and the lens without installing a thermistor near the contact glass. It is an object to provide an optical unit of a copying machine which has a simple structure at low cost.

[0004]

The gist of the present invention resides in that, in claim 1, a contact glass on which an original is placed, an exposure lamp for exposing the original on the contact glass, and its reflected light are provided. In an optical unit of a copying machine including a mirror and a lens for guiding the photoconductor, and a cooling fan for cooling the exposure lamp, a temperature detecting means for detecting the temperature of the photoconductor is provided near the photoconductor. ,
The drive of the cooling fan is determined according to whether the drive of the main body of the copying machine is turned on or off, and whether the detection result of the temperature detection means has reached a set temperature.
The set temperature is set in two or more steps according to the size of the original, and in claim 3, the set temperature is set to be higher during double-sided copying than during single-sided copying. It is that you are.

[0005]

Therefore, according to the first aspect of the present invention, the cooling fan for cooling the exposure lamp is driven, whether the driving of the main body of the copying machine is turned on or off, and the detection result of the temperature detection means reaches the set temperature. Whether or not the cooling fan blows more than necessary to prevent the mirrors, lenses, etc. from becoming dirty with dust and dust, and the temperature rise of the optical unit and contact glass is also prevented by deciding whether or not the temperature will rise. It Further, in the present invention, the set temperature is set in two or more stages according to the size of the original document. For example, if the original size is small, the calorific value is low. It is prevented that the air is blown as described above, and has the same effect as that of claim 1. Further, in claim 3, the temperature of the photoconductor rises more rapidly during double-sided copying than in single-sided copying. Therefore, the set temperature during double-sided copying is set higher than during single-sided copying. Has the same effect as.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, the image forming unit 10 is arranged above the paper feeding unit 11, and the image forming unit 1
An ADF (Automatic Document Feeder) 17 is arranged above 0.

A contact glass 6 is arranged on the upper surface of the image forming unit 10. On the lower surface side of the contact glass 6, a halogen lamp 1 which is an exposure lamp for irradiating an original with light, and an original image on a photosensitive drum 12 (described later). ), A mirror 7, a lens 8, an optical unit 9 including a cooling fan 4 for cooling the vicinity of the halogen lamp 1, and the like, and a photoconductor drum for forming an electrostatic latent image of an original document under the optical unit 9. 12. A developing unit 13 and a transfer unit 14 for transferring the toner image developed by the developing unit 13 onto a transfer sheet are arranged around the photosensitive drum 12, and the transfer image is fixed on the downstream side of the transfer unit 14. The fixing unit 15 is provided below the fixing unit 15 and the double-sided unit 16 for double-sided copying is arranged.

As shown in FIG. 2, a drum thermistor 21, which is a temperature detecting means for detecting the temperature of the photosensitive drum 12, collects the toner remaining on the photosensitive drum 12, and a cleaning brush 22 and a cleaning blade 23.
It is arranged at a position close to the photoconductor drum 12 upstream of the cleaning unit 25 having the above. The main control in this configuration is as shown in FIG.
1, the main control unit 3 for controlling the drum thermistor 21 and the like
0 and an optical control unit 40 for controlling the cooling fan 4, the document size sensor 32, etc., and the main control unit 30 and the optical control unit 40 mutually exchange information.
In the above configuration, the original image obtained by irradiating the original on the contact glass 6 with light from the halogen lamp 1 is emitted onto the photosensitive drum 12 via the mirror 7 and the lens 8, and the toner image is formed by the developing unit 13. It is formed.
On the other hand, the transfer paper sent from the paper supply unit 11 is guided to below the photoconductor drum 12 through the conveyance path, and the toner image is transferred by the transfer unit 14. Then, after the toner image is fused on the transfer paper by the fixing unit 15, the transfer paper is ejected to the outside of the machine.

When the double-sided copy mode is selected, the transfer sheets are stacked on the double-sided unit 16 and fed again to the photosensitive drum 12 side with the front and back sides reversed. Regarding the relationship between the temperature of the contact glass 6 and the temperature of the photosensitive drum 12 during continuous copying, as shown in FIG.
Contact glass 6 temperature Tg is t ₀ (contact glass 5
When the thermistor output (not shown) in the vicinity reaches t ₀ ), the cooling fan 4 is turned on to prevent the temperature from rising as shown by the broken line. Also in this embodiment, similarly, the photosensitive drum temperature Td gradually rises as shown in the figure, so that the photosensitive drum temperature Td, that is, the output of the drum thermistor 21 becomes t ₁ . By the way, turning on the cooling fan 4 prevents the temperature from rising.

Next, depending on the size of the original, the cooling fan 4
A case of changing the driving temperature of will be described. As shown in FIG. 5, even when the copy time is the same, when the document size is A3, the rising curve of the contact glass temperature Tg is gentler than in the case of A4, and the photosensitive drum temperature Td is t ₁ as in A4. When the cooling fan 4 is turned on, air is blown into the optical unit 11 more than necessary, which results in hastening the dirt on the mirror 7 and the like. To prevent this, A4
When the size is smaller than A3, the photosensitive drum temperature Td
Turns on the cooling fan 4 at t ₂ (t ₁ <t ₂ ).

Further, as shown in FIG. 6, during double-sided copying, the transfer sheet heated once through the fixing unit 15 comes into contact with the photosensitive drum 12 again. Rise sharply compared. Therefore, when the photosensitive drum temperature Td becomes t ₃ (t ₁ <t ₃ ), the cooling fan 4 is turned on.

Next, the processing procedure of this embodiment will be described with reference to a flow chart. As shown in FIG. 7, first, it is judged whether or not the copy is in the single-sided mode, and if it is the double-sided mode and the photosensitive drum temperature Td is t ₃ , the cooling fan is turned on when the main motor is on. 4 is turned on (steps 1, 2, 6, 7). Alternatively, when the copy is in the single-sided mode, the document size is A4 or larger and the photosensitive drum temperature Td
If t is t ₂ , the cooling fan 4 is turned on when the main motor is on (steps 1, 3, 4, 6, 7).
If the copy is in the single-sided mode and the document size is A4 or smaller and the photosensitive drum temperature Td is t ₁ , the cooling fan 4 is turned on when the main motor is turned on (steps 1, 3, 5,). 6, 7).

[0013]

As described above, according to the first aspect of the present invention, the temperature detecting means for detecting the temperature of the photoconductor is provided in the vicinity of the photoconductor, and the cooling fan is driven by the drive of the main body of the copying machine. Since it is determined depending on the on / off state and whether the detection result of the temperature detecting means has reached the set temperature, it is possible to prevent the temperature rise of the optical unit and the contact glass at low cost, and more than necessary. It is possible to prevent the air from being blown to, and to minimize the dirt on the mirror, the lens and the like. Further, according to claim 2, since the set temperature is set in two or more stages according to the size of the document, it is possible to prevent air from being blown more than necessary, and the same effect as that of claim 1 is obtained. Can be expected. According to claim 3, the set temperature is set to that for double-sided copying.
Since it is set higher than that for single-sided copying, the same effect as that of claim 2 can be expected.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an entire system including an optical unit of a copying machine according to an embodiment of the present invention.

FIG. 2 is a configuration diagram in the vicinity of a photoconductor showing an arrangement of temperature detection means.

FIG. 3 is a block diagram showing a control system of this embodiment.

FIG. 4 is a characteristic diagram showing a relationship between a contact glass temperature and a photosensitive member temperature.

FIG. 5 is a characteristic diagram showing a difference in temperature rise of a photoconductor depending on a document size.

FIG. 6 is a characteristic diagram showing a difference in temperature rise of a photoconductor between single-sided copying and double-sided copying.

FIG. 7 is a flowchart showing a processing procedure of an operation.

FIG. 8 is a schematic configuration diagram showing an optical unit of a conventional copying machine.

[Explanation of reference numerals] 1 exposure lamp 4 cooling fan 6 contact glass 7 mirror 8 lens 21 temperature detection means

Claims (3)

[Claims] 1. A contact glass on which an original is placed, and an exposure lamp which exposes the original on the contact glass.
An optical unit of a copying machine, comprising a mirror and a lens for guiding the reflected light to a photoconductor, and a cooling fan for cooling the exposure lamp, a temperature detecting device for detecting the temperature of the photoconductor in the vicinity of the photoconductor. Means is provided, and the driving of the cooling fan is determined according to on / off of driving of the main body of the copying machine and whether the detection result of the temperature detecting means has reached a set temperature. Optical unit. 2. The set temperature is set in two or more stages according to the size of the original document.
The optical unit of the described copying machine. 3. The set temperature is that for double-sided copying,
2. The optical unit of a copying machine according to claim 1, wherein the optical unit is set to a height higher than that for single-sided copying.