JPS61179429A - Platen cooling device - Google Patents

Abstract

PURPOSE:To reduce the staining of a platen, etc., with dust by providing a control means which drives a fan which cools the platen heated by a light source for exposure a specific time after copying operation is started. CONSTITUTION:When copying operation is started with a copy start button 26 while an original 11 is mounted on the platen 2, a CPU21 starts measuring the copy time and monitors whether the measured time reaches a specific time, e.g. four minutes or not. When the copying operation is completed within the specific time, a copy stand-by mode is entered. When not, the CPU supplies a driving signal to a fan driving circuit 25. Consequently, the fan 17 begins to be driven and the platen 2 is cooled. When the driving motor for the photosen sitive body 10 stops after the copying operation,the fan 17 also stops. Thus, the fan is not driven when the copying operation is completed within the specific time, so the staining of the platen, etc., with dust, etc., is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a platen cooling device in an electronic copying machine.

"Prior Art" In an electronic copying machine, an original is placed on a platen, and an image is created through the steps of forming an electrostatic latent image by exposure, developing, transferring, and fixing.

FIG. 4 shows an example of such a conventional electronic copying machine.

In this electronic copying machine, a platen 2 is provided on the top of a main body 1. An exposure section 3 is provided below the platen 1. The exposure section 3 includes a lamp 4, first to third mirrors 5 to 7, a lens 8, a fourth mirror 9, and the like. A drum-shaped photoreceptor 10 is provided below the exposure section 3 .

When making copies using this electronic copying machine, first
A document 11 is placed on the platen cover 12 and pressed down. When a copy start button on an operation panel (not shown) is pressed in this state, the photoreceptor 10 is rotated in the direction of the arrow, and its surface is charged by the charger 13. Thereafter, when the lamp 4 is turned on at a predetermined timing and is moved together with the first mirror 5 in the direction indicated by the arrow, the reflected light from the document 11 placed on the platen 1 is transmitted to the first to third mirrors. 5-7,
The photoreceptor I passes through the lens 8 and the fourth mirror 9, respectively.
An image is formed on O to form an electrostatic latent image. At this time, the second and third mirrors 6.7 are moved in the direction of the arrow at half the moving speed of the lamp 4, and the photoreceptor 10 is moved from the original 11.
so that the optical distance to always remains constant. The electrostatic latent image is developed at a location facing the developing device 14, and a toner image is formed.

On the other hand, paper 1 fed out from a paper cassette (not shown)
5 is transported as shown by arrow B by a transport device, also not shown, and is sent between the photoreceptor lO and a transfer device 16 provided opposite thereto. At this time, transfer device 1
6, the toner image on the photoreceptor 10 is transferred onto the paper 15. The paper 15 after the transfer is peeled off from the photoreceptor 10, sent to a fixing device (not shown), fixed thereon, and then discharged to a discharge tray (also not shown).

By the way, in such an electronic copying machine, the exposure lamp 4
Various lamps are used for this purpose, one of which is a halogen lamp. Halogen lamps have many advantages: they have a high color temperature, and their initial brightness and color temperature remain stable throughout their lifespan.In addition, their light energy rises quickly at startup, and they are stable during lighting. has advantages. However, with halogen lamps, most of the electrical energy is turned into heat, which increases the temperature inside the copying machine and causes various problems. One of them is an increase in the temperature of the platen.

If the temperature of the platen becomes abnormally high, there is a risk that an operator may get burned by touching it, and the platen itself may be damaged. Therefore, as shown in FIG. 4, the platen 2 is cooled by installing a fan 17 near the platen 2 and driving the fan 17 from the time when copying starts until a certain period of time has elapsed after copying ends. This is commonly done. In addition, various measures have been taken to improve the cooling effect (for example, Utility Model Application No. 54-243).
No. 42, Utility Model No. 53-110130, Utility Model No. 53-1
No. 11731, No. 115040, No. 115040, No. 115040, No. 5
No. 6-74456, Jitko No. 57-8024, Special Publication No. 5
No. 7-12153).

By the way, in such a conventional electronic copying machine, the fan 17
When the is driven, dirt and dust move along with the air flow generated at that time, and end up adhering to the platen 2, the mirror of the exposure section 3, and the like. Therefore, a filter (not shown) is provided in front of the fan 17 to remove dirt and dust.

"Problems to be Solved by the Invention" As described above, in the conventional electronic copying machine, dirt and dust are removed by a filter provided in front of the fan 17. However, since it is not possible to remove dirt, dust, paper powder, toner, etc. existing on the discharge side of the fan 17, there is a problem in that these adhere to the platen 2 and the like, resulting in inferior image quality.

In view of the above circumstances, it is an object of the present invention to provide a platen cooling device that can considerably reduce the adhesion of dust and the like to the platen and the like.

"Means for Solving the Problem" In the present invention, the platen cooling device is provided with a control means for driving a fan for cooling the platen when a predetermined period of time has elapsed after the start of copying, and the copying is completed within the predetermined period of time. The fan is not driven when the process ends within the specified time.

Here, the predetermined time will be explained with reference to FIG. 3. FIG. 3 shows the temperature change of the platen during continuous copying.

In this figure, the curve shown by the dashed line represents the temperature change of the platen when the fan is not used.

The dotted curve represents the temperature change of the platen when the fan is driven simultaneously with the start of copying.

The curve shown by the solid line represents the temperature change of the platen when the fan is driven 4 minutes after the start of copying.

As is clear from this figure, the temperature of the platen changes in almost the same way when the fan is driven 4 minutes after the start of copying as when it is driven simultaneously with the start of copying.

Therefore, the above-mentioned predetermined time refers to a certain period of time when the temperature of the platen changes almost in the same way even if the fan is driven a certain time after the start of copying, as when it is started at the same time as the start of copying. .

Incidentally, although it depends on the model, one copying operation is often completed within four minutes after it starts. For example, 1 page of manuscript is 1
When the number of copies is 20 or less, such as when making five copies or making three copies of five originals, the work is often completed within one minute from the start. Furthermore, for example, when copying 15 copies of 5 originals or 4 copies of 20 originals, the work is often completed within 4 minutes from the start. For this reason, one copying operation is often completed within four minutes from the start.

Therefore, if the predetermined time is set to 4 minutes, for example, most of the copying work will be completed within this time. For this reason, the frequency of driving the fan is drastically reduced, and as a result, the adhesion of dust and the like to the platen and the like is considerably reduced. And 4
The temperature of the platen does not become abnormally high in about 1 minute, and safety is sufficiently ensured.

"Example" The present invention will be described in detail with reference to Examples below.

FIG. 1 shows the main parts of the electric circuit of a platen cooling device in one embodiment of the present invention.

A CP[J (central processing unit) 21 is connected to a read-only memory 23, a random access memory 24$, and a fan drive circuit 25 through a data bus 22, respectively. This platen cooling device is provided with a copy start button 26 of an electronic copying machine as an input means.
Data is input through a data bus 22.

Next, the operation of this platen cooling device will be explained with reference to a flowchart (FIG. 2) and FIG. 4.

If the electronic copying machine is in copy standby mode, C
The PU 21 monitors whether or not the copy start button 16 is pressed (step ■). When the original 11 is placed on the platen 2 and the copy start button 26 is pressed (Y) to start copying, the CPU 21 starts measuring the copying time (step ■), and the time t is set to a predetermined time to ( For example, 4 minutes) is monitored (step ■). If copying is not completed within the specified time and 1 = 10, (
N), the electronic copying machine enters copy standby mode.

If the copying is not completed within the predetermined time and 1=10, the CPU 21 executes the fan drive circuit 2.
A drive signal is supplied to 5. As a result, from this point in time, that is, after a predetermined time (4 minutes) has elapsed, the fan 17 starts to be driven, and the platen 2 is cooled. When the copying is completed and the motor (not shown) for rotating the photoreceptor 10 stops, the fan 17 also stops, and the electronic copying machine enters a copying standby mode.

"Effects of the Invention" As explained above, according to the present invention, the fan is not driven when copying is completed within a predetermined time, so it is possible to reduce the possibility of the platen, etc. becoming dirty with dust, etc. . Moreover, since most copying operations are often completed within the predetermined time (for example, 4 minutes), it is possible to considerably reduce the amount of dirt on the platen and the like. Therefore, the platen and the like are less likely to be contaminated with dust and the like, and poor image quality caused by this can be satisfactorily prevented for a long period of time.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the main parts of the electric circuit of a platen cooling device in an embodiment of the present invention, Fig. 2 is a flowchart for explaining the operation of the cooling device, and Fig. 3 is a continuous copy of the Figure 4 shows the temperature change of the platen when
The figure is a partial schematic diagram showing an example of a conventional electronic copying machine. 2...Platen, 4...Lamp, 5-7.9...Mirror, 8...Lens, lO...Photoconductor, 11...Manuscript, 17...Fan, 21...CPU. 25...Fan drive circuit, 26...Copy start button. Applicant Fuji Xerox Co., Ltd. Agent Patent Attorney Umeo Yamauchi Figure 4 Figure 2

Claims (1)

[Claims] The apparatus includes a platen on which a document is placed, a fan for cooling the platen heated by lighting of an exposure light source, and a control means for driving the fan when a predetermined time has elapsed from the start of copying. A platen cooling device featuring: