JPS6343752B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention mainly relates to a side erase device for an electrostatic latent image on a photoreceptor in an electrophotographic copying machine.

Prior Art Generally, in an electrophotographic copying machine, a pressure plate presses an original to make a copy. In the case of sheet originals where the pressure plate can be closed against the contact glass, the back side of the pressure plate is white and light is reflected from areas outside the document, exposing the entire area of the photoreceptor, so it is compatible with originals on the surface of the photoreceptor. The toner will not adhere in a dense manner outside the area. However, in the case of a thick original such as a so-called book original, copying is performed with the pressure plate open, resulting in so-called black solid areas where toner is strongly adhered to the side portions of the surface of the photoreceptor. This is because when the pressure plate is open, reflected light from areas outside the original does not come, so the electrostatic latent image formed on the photoreceptor remains unexposed on the image area corresponding to the original and on both sides. This is because the toner is electrostatically attached to the non-image area. Normally, an electrophotographic copying machine has a cleaning device that cleans the toner remaining on the surface of the photoreceptor after the toner image is transferred to transfer paper, but when copying with an open pressure plate, the photoreceptor The black solid areas on the sides of the body must be cleaned every time. This increases the burden on the cleaning device, shortens its lifespan, and
This causes problems such as high toner consumption and toner scattering inside the machine. Therefore, in order to eliminate the occurrence of solid black areas on the sides of the photoreceptor, partial erasure of the latent image has been practiced.

Such side erasing of the latent image can be achieved relatively easily in the case of a copying machine that only handles copy paper of standard sizes, such as B4 and A4 sizes. However, in copiers that can use paper of any size other than standard sizes as copy paper, for example, in copiers that are equipped with a so-called manual paper feed mechanism in addition to a cassette paper feed mechanism, the sides of the latent image can be erased as desired. This is relatively difficult. This is because the advantage of the manual paper feed mechanism is that even irregularly sized paper can be set and fed. for example,
It is also possible to select some of the erase lamp groups to suit all sizes and emit light.
This requires a linear paper size detection device and a multi-stage erase device capable of randomly partitioning erase lamp groups, resulting in problems such as a complicated circuit and increased costs.

Purpose The present invention provides a paper size detection device and an erase lamp group that can be used without complicating the structure of the paper size detection device and the erase lamp group, even when paper of an irregular size is fed, such as when using a manual paper feed mechanism. It is an object of the present invention to provide a side erase device capable of side erasing an electrostatic latent image on a photoreceptor at an optimal size corresponding to an irregular size.

Configuration The configuration of the present invention will be described below based on one embodiment.

FIG. 1 shows an overall outline of an electrophotographic copying machine that performs side erasing of an electrostatic latent image on a photoreceptor according to the present invention. A indicates the cassette paper feed section, and B indicates the manual paper feed section. The photosensitive drum 1 is rotated by a main drive motor 10 in the direction of the arrow. Around the photosensitive drum 1, a charging charger 2, a side erase device 3, a slit exposure optical system, a developing device 4, a transfer charger 5, a separation charger 6,
A cleaning device 7 is arranged. 8 is a scanner including an exposure lamp 9, which moves back and forth beneath the contact glass 11.

The photosensitive drum 1 is uniformly charged in advance by a charging charger 2. The document on the contact glass 11 is irradiated when the scanner 8 moves back and forth, and the photosensitive drum 1 is exposed to light reflected from the document. Charges on the areas exposed to the light, that is, areas corresponding to the white portions of the document, are erased, while charges on the portions corresponding to the black portions of the document remain as they are, creating a latent image. Concurrently with this, the side erase device 3 erases the non-image portion of the latent image, that is, the area on the side of the photosensitive drum with light. This side-erased latent image passes through a developing device 4 and is developed with toner.

The manual feed section B has a manual feed table 13 that can be tilted out of the machine around a shaft 12.
By tilting 3 out of the machine and opening it, manual feed mode detection switch S1 is turned on.
The cassette paper feed section A and the manual paper feed section B are respectively provided with dedicated paper feed rollers 14 and paper feed clutches 15, which are selectively used. For the toner image on the photoreceptor, a transfer sheet is sent out from the paper feed section A or B to the registration rollers 16 in advance, and waits for it to be sent out from the registration rollers 16.
The presence or absence of transfer paper in this standby state is detected by a paper detection sensor S2.

The transfer paper waiting on the registration roller 16 is
It is sent out by turning on the registration roller drive crack 17. The timing of this clutch ON is synchronized so that the leading edge of the transfer paper coincides with the leading edge of the toner image on the photoreceptor. The superimposed body of the transfer paper and toner image passes through a transfer charger 5 and a separation charger 6, thereby transferring the toner image from the photoreceptor to the transfer paper and separating the paper from the photoreceptor after the transfer. will be carried out. The separated paper is sent to the fixing device 19 through the conveyance path 18, and is ejected outside the machine through the ejection roller 20. When the paper is safely discharged from the machine, the paper detection sensor (discharge switch) S3 provided near the discharge roller 20 is turned off.

After the transfer paper is separated, residual toner is removed from the surface of the photoreceptor by a cleaning device 7, and the photoreceptor surface is used again for the next copying cycle.

In order to determine the size of the paper to be fed, a size identification code 22 made up of, for example, four magnets is attached to the outer frame of the cassette 21 in the cassette paper feeder A, and a size identification code 22 made up of, for example, four magnets is attached to the outer frame of the cassette 21 in the copying machine. A size detection section 23 consisting of four reed switches is provided. In Japan, the standard paper sizes fed in cassettes are mostly A and B, such as A3, B4, A4, and B5.

On the other hand, since the manual paper feed section B has a problem with irregular sizes that cannot be handled by the cassette paper feed section A, in order to guide the side edges of the paper, it is placed on the manual feed table 13 so that it can be moved according to the paper size. It has a fence 24. In this embodiment, as shown in FIG.
Two fences 24a, 24b moving along
When one fence 24a is manually moved, the other fence 24b moves in conjunction with the other fence 24b, and the width between them changes.

In FIG. 4, there is a
Two permanent magnets 26 are provided. 27 is a stopper that limits the movement of the fence 24, and this may be limited by the length of the slot 25 mentioned above. A printed board 28 is provided in the manual feed table 13 in parallel with the upper plate 13', and a plurality of non-contact switches 29 are arranged at regular width positions on the printed board. In this example, three reed switches 29
A, 29B, and 29C are provided at positions corresponding to the longitudinal lengths of A4, B5, and A5 (see FIG. 5).
In this embodiment, the magnet 26 and the reed switch 29
Guide fence 2 by A, 29B, 29C
A fence position detection sensor for detecting the position of No. 4 is configured.

FIG. 5 shows the relationship between the erase area and the light emitting area of the erase device 3 when the photosensitive drum 1 is viewed in cross section along its axis. The erase device 3 leaves an area corresponding to the vertical length of A5 size determined as the minimum width, and sequentially erases the area on both sides of the area.
The light emitting section 30 is divided into areas ○C, ○B, ○A, and ○D with boundaries corresponding to the longitudinal lengths of B5, A4, and B4. Such a light emitting section 30 can be configured by, for example, a light emitting diode array.

These light emitting areas, that is, erase areas ○c, ○b,
○A and ○D are used selectively as follows according to the size of paper being fed. That is, in the case of paper feeding from a cassette, erasing is performed with the same width as the size of the cassette detected by the size detection section 23 described in FIG. 2, or more precisely, the size of the transfer paper in the cassette. Furthermore, in the case of manually fed transfer paper of an irregular size, the erase width is wider than that of the transfer paper so that so-called "white spots" do not occur inside the transfer paper. However, at this time, erasing is performed so that the black solid area other than the transfer paper is minimized as much as possible.

Although the manual paper feed size detection mechanism shown in FIG. , either reed switch 29A, 29
Area 31 where B and 29C are ON (shaded area), and neither reed switch is ON.
OFF area (area not shaded) 32, 33,
34 occurs. This is because the fence 24 of the manual feed table moves linearly and can be set at any position, but since it may be in this OFF area, in order to erase with as few solid black areas as possible, it is necessary to turn on the light emission of the above erase device. Area ○ha, ○ro,
The problem is which area of ○A and ○D should be operated as the erase area. For example, if all reed switches 29A, 29B, and 29C are OFF, it is unclear in which of the three OFF regions 32 the magnet 26 is located, so perhaps erasing is limited to only the outermost region ○2. , when the actual fence position is in the OFF region 34, this does not mean that control has been performed to minimize the black solid portion.

Therefore, in the present invention, the reed switch 29
OFF area 32 outside A, reed switch 39
OFF area 33 between A-29B, reed switch 2
In order to recognize which of the OFF areas between 9B and 29C is, the previous reed switch was ON or
The OFF state is memorized and the erase area is determined by estimating the actual position of the fence 24 based on the combination with the currently detected ON or OFF state of the reed switch. However, since only the previous data is stored, for example, as shown in Fig. 6, if the reed switch 29B was in the ON state last time, then all the reed switches 29A, 29B, and 29C are in the ON state.
Even if data is obtained that it was in the OFF state,
From this alone, it is unclear whether the fence 24 and therefore the magnet 26 have moved to the right or left of the reed switch 29B. Therefore, in this embodiment, emphasis is placed on preventing white spots from appearing in the copy image, and in the case of the outer erase area, that is, in the case of FIG.
○Turn on d.

FIG. 7 shows a specific example of carrying out the method of side erasing a photoreceptor according to the present invention using a microcomputer (not shown).

In the flowchart of FIG. 7a, starting from START, data memories M _H and M _L are first set to zero. M _H means the upper 4 bits of the 8-bit memory, and _ML means the lower 4 bits, as shown in the lower part of FIG. 7d.
Manual feed table 13 is opened and detection switch S1 is activated.
Check whether it is in manual feed mode depending on whether it is turned on. If you are in manual feed mode,
Entering the manual feed detection subroutine shown in FIG. 7c,
Otherwise, proceed to the next step (point Q).

In the manual feed detection subroutine of FIG. 7c,
The program is M _L in data memory M _H and 1 in M _L.
is stored and reed switch 29A is ON.
Set "1" to M _L , "2" if 29B is ON,
If 29C is ON, "4" is stored, and if all reed switches 29 are ON, "0/" is stored. Now, the ON/OFF state data of the reed switch at the previous fence position is stored in the lower 4 bits of the data memory.

Returning to point Q in FIG. 7a, when the print button is turned on, the main drive motor 10 and both the transfer and separation chargers 5 and 6 are turned on, and the timer _T1 is set. After the timer T ₁ has expired, the paper feed clutch 15 for the cassette will be
Turn on and execute the erase drive subroutine. This cassette erase drive subroutine is separate from the manual erase drive subroutine described later, and is based on the paper size directly detected by the size detection unit 23 in FIG. Erase.

However, in the manual feed mode, the manual feed clutch 15 is turned on and the manual feed detection subroutine shown in FIG. 7c is entered again. In this manual feed detection subroutine, the previous data M _L is stored in the upper 4 bits of the data memory, and the lower 4 bits are stored with data (“1”,
``2'', ``4'', or ``0/'') is entered.

The program then proceeds to the manual erase drive subroutine (FIG. 7d).

In the manual erase drive subroutine shown in FIG. 7d, the contents of the data memory, ie, the upper 4 bits and lower 4 bits, are loaded into the accumulator _Acc . Current fence position data (lower bit)
is “0/”, that is, both reed switches 29
Suppose it is in the OFF state. In this case, if the previous fence position data (upper 4 bits) was "1", that is, the read switch 29A was in the ON state, the paper set in manual paper feed section B may be slightly larger or smaller than A4 size. be. Accordingly
When A _cc = 10/, the erase area ○d is lit. This can be done by lighting up the erase area ○a at the same time.
This is because white spots will appear in the image if the paper is larger than A4 size. When the previous fence position data is "0/", that is, when A _cc =0/0/, since it is unknown, only the erase area ○2 is lit for safety.

Similarly, if A _cc = 20/, that is, last time reed switch 29B was ON and this time all reed switches are ON.
When it is OFF, the paper is slightly larger or smaller than B5 size, so to eliminate white spots,
Turn on the erase areas ○I○○ outside the reed switch 29A.

If A _cc = 40/, that is, the previous reed switch 2
When 9C is ON and all are OFF this time, the paper is
Read switch 2 as it is slightly larger than A5 size.
The erase area outside 9B is lit.

Regardless of the previous data, if the current fence position is reed switch 29A,
It is clear that the paper is A4 size, so
When A _cc =11, A _cc =41, and A _cc =0/1, erase areas ○A to ○D immediately adjacent to the read switch 29A are lit. Similarly, A _cc = 12, A _cc =
22. When A _cc = 42 and A _cc = 0/2, the erase areas ○○○○○○d are lit. Also, A _cc = 14, A _cc = 24, A _cc
= 44, A _cc = 0/4, the erase area ○I○Ro○H○ni is lit.

In this way, a predetermined latent image side erase is performed,
Proceeding to point R in FIG. 7a, the program turns on the optical scanner feed clutch (not shown) and turns on the exposure lamp 9. Sukiyana 8 begins to move forward. When the paper has been fed to the paper detection sensor S2, the paper feed clutch 15 is turned OFF. The leading edge of the paper is stopped on the registration rollers 16.
At a predetermined timing, a registration switch (not shown) is turned on and the registration roller drive clutch 1 is turned on.
7 enters, and the paper is sent out to the photosensitive drum 1. After the trailing edge of the paper passes through the paper detection sensor S2,
When the sensor turns off, timer _T2 is set.

In FIG. 7b, when the _T2 timer times up, the scanner feed switch (not shown) is turned off and the scanner return switch (not shown) is turned on to make the scanner 8 move back. At the same time, the exposure lamp 9 is turned off and the registration roller drive clutch 17 is turned off. When the scanner 8 returns to the home position, a home position switch (not shown) is turned on. When the home position switch turns on, turn off the scanner return switch.

In the flow starting from point V, the program turns OFF the paper ejection switch S3, sets timer _T3 , and turns on the main motor 10 after a predetermined period of time.
Turn OFF and both transfer and separation chargers 5 and 6.
OFF and all erase lamps. Then, loop to Figure 7a.

Effects According to the present invention, the fence position detection sensors are not arranged in close contact with each other, but are arranged at intervals, and the light emitting parts do not emit light in a very small area, but only in several areas. It is provided so as to emit light in separate areas, so that the paper size detection device and the erase lamp group can be easily constructed. In this case, if the paper to be fed cannot be detected by these fence position detection sensors because the fence position detection sensors are arranged at intervals, the fence position detection data is determined based on the fence position detection data before the fence movement. Since the position and therefore the paper size are determined and the light emitting section emits light based on this paper size, side erasing can be performed reliably even when paper of an unusual size is fed. I can do it.

[Brief explanation of drawings]

Fig. 1 is an overall schematic diagram of a copying machine to which the side erase method of the present invention is applied, Fig. 2 is an explanatory diagram of a method for detecting the size of the cassette paper feed section, and Fig. 3 is a schematic perspective view of the table portion of the manual paper feed section. Figure 4 is a diagram showing a specific example of the size detection mechanism of the manual paper feed section, and Figure 5 is a diagram showing a specific example of the size detection mechanism of the manual paper feed section.
Figure 6 is an explanatory diagram of the erasing device and the erase area of the photoreceptor, Figure 6 is an explanatory diagram of the ON/OFF area of the fence magnet and reed switch, and Figure 7 is a flowchart showing a specific example of the side erase method of the present invention. It is a diagram. A...Cassette paper feed section, B...Manual paper feed section,
1... Photosensitive drum, 2... Charger for charging,
3... Erase device, 4... Developing device, 5... Transfer charger, 6... Separation charger, 7...
...Cleaning device, 8...Scanner, 9...
Exposure lamp, 13... Manual feed table, 21...
Cassette, 23...Size detection section, 24...Fence, 26...Magnet, 27...Stopper, 28...
...Printed board, 29...Contactless switch (reed switch), 30...Light emitting section.

Claims (1)

[Scope of Claims] 1. The side of an electrostatic latent image on a photoconductor attached to an electrophotographic device that feeds the paper to a photoconductor while guiding the paper by a guide fence that is movable in the width direction of the paper. The erase device is equipped with a light emitting section that is arranged to face a photoreceptor and can emit light in each of several regions divided across the width of the photoreceptor, and the light emitting means is arranged in each region. In a side erase device that erases charges on the side portions of an electrostatic latent image on a photoconductor in accordance with the paper size by selectively emitting light, two devices are arranged at intervals in the width direction of the paper.
A plurality of fence position detection sensors detect the guide fence and output a signal, and when the guide fence is moved in the width direction of the paper and aligned with the side of the paper, one of the plurality of fence position detection sensors is detected. When a guide fence is detected, the paper size is determined based on the signal from the fence position detection sensor, and on the other hand, when none of the plurality of fence position detection sensors detects the guide fence, the paper size is determined based on the signal from the fence position detection sensor. A control means that determines the paper size based on a signal from the fence position detection sensor and causes a light emitting section corresponding to a side portion of the photoreceptor corresponding to an area outside the determined paper size to emit light. Side erase device.