JPS622300B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a copying machine, and more particularly to a structure for preventing temperature rise due to an exposure lamp of a copying machine that sequentially exposes a photoconductor by irradiating a copy original conveyed in one direction with an exposure lamp. .

Generally, in this type of copying machine, the original to be copied is conveyed in one direction on an original platen made of a transparent plate such as glass using transport rollers, and the original surface is illuminated by an exposure lamp from the underside of the original platen. However, as the copy document is conveyed, the document image is sequentially exposed on the surface of the photoreceptor.

However, since this type of copying machine uses a high-intensity exposure lamp such as a halogen lamp, it also emits a large amount of heat rays, causing a problem of temperature rise around the document transport section, especially on the glass surface of the document table.
In particular, when copy documents are continuously fed into the document transport section, the time from when the exposure lamp turns off when the previous copy document passes until it is turned on when the next copy document is inserted becomes extremely short, causing the temperature to rise. is remarkable.

In order to prevent such a temperature rise, conventional measures have been taken, such as installing heat-absorbing glass between the exposure lamp and the document glass, or providing an air blower to cool the document glass surface. There is.

However, as the heat ray absorption efficiency of the heat ray absorption glass increases, the heat insulation effect increases, but on the other hand, the amount of light required for exposure also decreases. Therefore, in order to obtain a predetermined amount of light, it is necessary to take measures such as increasing the input voltage to the exposure lamp, which adversely affects the life of the exposure lamp. Moreover, low-priced materials with low heat ray absorption efficiency are extremely weak in terms of heat insulation. Further, in the case where a blowing means is provided to cool the document table glass, special means such as a fan or a duct for blowing air are required, and the cooling effect is not as high as expected.

On the other hand, in order to allow time for the exposure lamp to cool down, it is conceivable to turn on an insertion prohibition lamp that prohibits the insertion of the next copy document, but it is possible to insert a copy document even while the lamp is lit. Therefore, it is not always possible to reliably prevent a temperature rise.

The present invention has been made in view of the above drawbacks.
In order to prevent the glass surface temperature of the exposure section from rising above a predetermined value after the exposure lamp is turned off due to the conveyance of the copy document, a blocking means is provided to prevent the exposure lamp from being turned on next time for a predetermined period of time. Accordingly, it is an object of the present invention to provide a copying machine that prevents a rise in temperature around the document conveying section, particularly on the glass surface of the document table, by providing cooling time for the exposure lamp.

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

1 and 2A and 2B show a first embodiment of the present invention, in which a photosensitive drum 2 is located approximately in the center of the main body 1.
is installed so as to be rotatably driven in a counterclockwise direction, and a well-known charging charger 3, a transfer roller 5, an eraser lamp 6, and an image forming optical system 7 are arranged around it. The image forming optical system 7 includes an exposure lamp 8, a first
~Third mirrors 9a, 9b, 9c, projection lens 1
0 and slit 11. The illumination light from the exposure lamp 8 is reflected by the original image surface of the copy original 34a that is conveyed to the right on the original platen glass 32 as described below, and is reflected by the first mirror 9a, the projection lens 10, the second, and the third The light is reflected by the mirrors 9b and 9c, and is sequentially exposed to the surface of the photosensitive drum 2 through the slit 11.

Also, on the left side of the main body 1 is a roll of copy paper 12.
Paper feed cassette 13 and cooling fan 1 containing
4. On the right side, a developing device 15 using a liquid developer, a fixing device 16 composed of a heat roller 17 and a pressure belt 18 are installed, respectively.

The paper conveyance path includes a pair of paper feed rollers 19, conveyance rollers 20a and 20b, a squeeze roller 21, and a guide plate 2.
A cutter 23 is installed immediately after the paper feed roller 19, and a separation claw 24 is installed immediately after the transfer roller 5. These devices and members are well-known.

The fixing device 16 is configured to eject the copy paper 12 from the bottom of the main body 1 in order to effectively utilize the heat of the heat roller 17. Therefore, a removable installation stand (not shown) equipped with a tray (not shown) is provided below the main body 1.

The document conveyance means 25 is installed on the upper surface of the main body 1, and includes a document conveyance roller 26 that is rotationally driven.
a, 26b, 26c and driven rollers 27a, 27
b, 27c, a document insertion prohibition guide 29 provided so as to be removable in and out of the document insertion section 28, a solenoid 30 for driving the guide 29, a document detection switch _SW1 provided immediately after the document transport roller 26a, and a document ejection A document table glass 32 is installed between document transport rollers 26b and 26c.

When the copy document 34a is not fed into the document conveyance means 25, the switch _SW1 is in an off state, the solenoid 30 is also turned off, and the document insertion prohibition guide 29 is retracted from the document insertion section 28.

In this state, when the print switch (not shown) is turned on, the document transport rollers 26a, 26b, 26
c is driven, and the copy original 34a is inserted from the original insertion section 28 and is transported to the right by the original transport roller 26a and the driven roller 27a. At the same time that the leading edge of the copy document 34a turns on the switch SW ₁ , the exposure lamp 8 lights up, and as shown in FIG. 29 enters the document insertion section 28 and prevents the insertion of the next copy document 34b as shown in FIG.

The copy document 34a is conveyed by document conveyance rollers 26a, 26b, 26c and driven rollers 27a, 27b, 27c while climbing over this guide 29,
The exposure lamp 8 is placed on the original table glass 32 as described above.
After receiving illumination from the original, the document is discharged onto the document discharge guide plate 31. The rear edge of the copy document 34a is the switch.
When the user leaves SW ₁ , the switch SW ₁ turns off, but the timer 33 operates for t ₁ + t ₂ hours after the switch SW ₁ turns off, the solenoid 30 remains on, and the document insertion prohibition guide 29 closes the document insertion section. 28. On the other hand, the exposure lamp 8 is turned off when the rear end of the copy document 34a passes through the document table glass 32 by the operation of an appropriate delay circuit. When the set time of the timer 33 has elapsed, the solenoid 30 is turned off, the document insertion prohibition guide 29 is retracted from the document insertion section 28, and the next copy document 34b can be inserted. Next copy manuscript 34
When the tip of b turns on switch SW ₁ , the exposure lamp 8 lights up again.

That is, as shown in FIG. 2B, the solenoid 30
operates while the switch SW ₁ is on and the timer set time, and prevents the exposure lamp 8 from being turned on again for a predetermined period of time, and prevents the exposure lamp 8 from increasing the temperature of the transport unit, especially the document glass 32. To prevent.

3 and 4 show a second embodiment, in which the document transport roller 26a on the document insertion section 28 side is connected to the copy document 34.
After the completion of the conveyance, the drive is stopped for a certain period of time to prevent the next copy document from being conveyed, and a time period is set in which the exposure lamp 8 is turned off for that period of time to prevent the temperature of the conveyance section, especially the document table glass 32, from rising. It is something.

That is, the switch SW ₁ is used as a first detection switch, and a second detection switch SW ₂ is provided behind the document transport roller 26c, another document transport roller 26d and a driven roller 27d are provided, and the document transport rollers 26b, 26c are provided. , 26d and coaxially fixed sprockets 35b, 35c, 35d.
A drive belt 37 is independently stretched between a sprocket 35a fixed coaxially to the document conveying roller 26a and a clutch 36 coaxially fixed to the sprocket 35b.

The clutch 36 is turned on while the second detection switch SW ₂ is in the off state, that is, while the copy document 34 is not detected, and the document conveyance roller 26a is
It can be rotated together with b, 26c, and 26d. While the second detection switch _SW2 is on, that is, while detecting the copy original 34, it is turned off, and the original transport roller 26a rotates idly.

Therefore, when the first copy original 34 is inserted, the exposure lamp 8 lights up when the first detection switch SW ₁ is turned on, and the exposure lamp 8 lights up when the second detection switch SW ₂ is turned on. The clutch 36 is turned off, and the document conveying roller 26a rotates idly. In this state, the second copy document 34 cannot be conveyed successively. The exposure lamp 8 is arranged so that the rear end of the copy document 34 passes the first detection switch SW ₁ and the document platen glass 32
The light will be turned off when it passes. When the rear end of the copy document 34 passes the second detection switch _SW2 , the clutch 36 is turned on, the document conveyance roller 26a is driven to rotate, and the second copy document 34 can be conveyed.

After the exposure lamp 8 is turned off as described above,
The light is kept off until the rear end of the first copy original 34 passes the second detection switch _SW2 and the leading edge of the second copy original 34 turns on the first switch _SW1 . The existence of this light-off time prevents the exposure lamp 8 from rising in temperature.

Further, as a signal for turning off the clutch 36, as shown in _FIG . The clutch 3 is activated for a certain period of time preset in the timer 33.
6 may be turned off, the rotational drive of the document conveyance roller 26a is stopped, and the second copy document 34 may not be conveyed. At this time, the second detection switch _SW2 , the conveyance roller 26d, and the driven roller 27d shown in FIG. 3 are unnecessary.

Alternatively, if the second copy original is inserted after the first copy original, the time interval between the insertions is within a certain period of time after the exposure lamp 8 that illuminated the first copy original goes out. In this case, if the second copy original is conveyed without turning on the exposure lamp 8, the second copy original shown in FIGS. 3 and 4, which stops the second copy original, The detection switch _SW2 , clutch 36, etc. are not required.

Further, in this case, it is necessary to avoid feeding copy paper only when the exposure lamp 8 is off.

As is clear from the above explanation, in order to prevent the glass surface temperature of the exposure section from exceeding a predetermined value after the exposure lamp is turned off as the copy document is transported, the exposure lamp is turned on next. Since the device is equipped with a blocking means to prevent this from occurring for a specified period of time,
While a plurality of originals are inserted and transported, it is possible to reliably provide a period of time during which the exposure lamp is not turned on and cooled down, and it is possible to prevent a rise in temperature around the original transporting section, especially on the original platen glass. Moreover, there is no need to use heat-absorbing glass that reduces the amount of light or air blowing means that unnecessarily increases the size of the copying machine as in the conventional methods, and the temperature rise is more reliably achieved than simply turning on the copy document insertion prohibition lamp. It can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view showing the first embodiment of the present invention, FIG. 2 A and B are a circuit diagram and time chart of the one shown in FIG. 1, and FIG. FIG. 4 is a schematic diagram of the drive system of the one shown in FIG. 3, and FIGS. 5A and 5B are a circuit diagram and a time chart of another embodiment. 1... Copying machine main body, 2... Photosensitive drum, 8...
...Exposure lamp, 25...Document transport means, 26a,
26b, 26c, 26d...Document transport roller, 2
8...Document insertion section, 29...Document insertion prohibition guide, 30...Solenoid, 33...Timer, 3
4, 34a, 34b...copy original, 36...clutch, 37...drive belt, _SW1 , _SW2 ...detection switch.

Claims (1)

[Claims] 1. In a copying machine that sequentially exposes a photoconductor by irradiating a copy document transported in one direction with an exposure lamp,
means for detecting the leading edge of the copy document being conveyed before the exposure position and turning on an exposure lamp accordingly; means for turning off the exposure lamp when the copy document passes the exposure position; and means for turning off the exposure lamp when the copy document passes the exposure position. and means for preventing the copy original from being conveyed to the detection position in order to prevent the exposure lamp from being turned on as the leading edge of the copy original is detected for a predetermined period of time. Copy machine.