JPS59152462A - Two-color electrophotographic copying apparatus - Google Patents

Abstract

PURPOSE:To prevent waste of toner and adhesion of a carrier to a photosensitive body by stopping electrostatic charging when trouble is detected in primary or secondary charging, and destaticizing a photosensitive body by uniform illumination. CONSTITUTION:When the wire of a charger 22 for secondary electrostatic charging is broken during discharge and secondary charging is intercepted, the trouble is detected by a trailing edge of a detection signal II. Hereupon, primary and secondary charging control signals are turned off and a destaticizing lamp control signal is turned on by a control circuit, and at the same time, a control signal of a trouble display device is turned on. As a result, the supply of power to the chargers 21, 22 for primary and secondary charging are stopped, and the trouble is displayed on a trouble display device 302. A destaticizing lamp 303 is lighted to uniformly illuminate a photosensitive body and to destaticize it, thus preventing waste of a toner and adhesion of a carrier.

Description

[Detailed description of the invention] (Technical field) The present invention relates to a two-color electrophotographic copying apparatus.

(Prior art) Two photoconductive layers are laminated on a drum-shaped or belt-shaped conductive substrate, and one photoconductive layer mainly becomes a conductor when irradiated with light of a specific color. Using the prepared photoreceptor, apply 7:□t to this D photoreceptor, and then
．． A two-color electrophotographic method having a step of achieving primary and secondary charging is known (see, for example, Japanese Patent Laid-Open No. 54-56445).

Recently, a two-color electrophotographic system has been proposed that uses a photoreceptor as described above and a conventional electrophotographic photoreceptor.

Figure A'1 schematically shows the main parts of an example of such two-color electrophotographic copying using two photoreceptors.

The present invention relates at least to a two-color electrophotographic copying system using a photoreceptor having a photoconductive layer as described above. For example, we will explain the two-machine copying process in a simple manner, and also explain the problem that the present invention aims to solve. For the sake of concreteness of explanation, it is assumed that the two colors p='rw and the colors of the image are black and red.

In the figure, number 1 is the device glass, number 2 is the lamp, number +4-3.4,5,6,7.8 is the mirror, number 9 is the half mirror, number 9 is the half mirror, number 1 is the red filter. -,
The phase code FC indicates a red cut filter, respectively.

Further, numeral 10 indicates a photoconductor for black images, and numeral 20 indicates a photoconductor for red images.

The photoreceptor 1.0 is a normal electrophotographic photoreceptor having a temperature of 0.degree. C. and a 1NG photoconductive layer provided on a conductive substrate. Also, photoreceptor 20&'! ,, has a structure in which two photoconductive layers are provided on a conductive substrate.

11 around the light body 1O is a charger,
Reference numeral 12 indicates a developing device, and reference numeral 13 indicates a cleaner.

Around the photoreceptor 2Q'71, the reference numeral 21 indicates a charger for primary charging, the reference numeral 22 indicates a charger for secondary charging, the reference numeral 23by indicates a 1-image arrangement, and the reference numeral 24 indicates a cleaner.

Also, reference numeral 30 is a transfer belt, 31, 32° 33,
Reference numeral 34 indicates a charger, and reference numeral 35 indicates a fixing device.

In addition, the code O is a red/black two-color original, the code S is a recording medium,
For example, plain paper is shown.

. . . - The mirror 9 can selectively take the attitude shown by the solid line and the attitude shown by the broken line in the figure. Further, the red filter FR and the red cut filter FC can be selectively set in the optical path.

As shown in Figure 1, place the mirror 9 in the position shown by the solid line, place the red filter FR in the optical path, and place the original O on the original placing glass L. , when rung 2 is emitted, the reflected light from original O is reflected by mirrors 3, 4, 5.
．． The lens L goes to the nozzle mirror 9, and is divided into two optical paths by the half mirror 9, one of which passes through the red filter FR and mirror 6 to the optical body 0, and the other goes to the mirror 7. 8 and then photoreceptor 20. Then, by the action of the lens L, the original O is placed on each photoreceptor 10.20.
A slit-shaped image is formed.

Therefore, while rotating the photoreceptors 10 and 20 in the directions of the arrows, the mirror 3 and the mirror 3 are integrally moved to the right in the directions of the arrows, that is, in FIG. The F document O is slit-scanned, and at the same time, the mirror '-4°5 is also moved to the right as a unit at a speed of 1/27 of the moving speed of the mirror 3.
), the photoreceptor io.

20 can be slit exposed at the same time.

Prior to slit exposure, the 10 photoreceptors are uniformly charged to a predetermined polarity, for example negative polarity, by a Charcher 11.
Then, it undergoes slit exposure. Photoreceptor tuk, <Th
The emitted light becomes red light by passing through the red filter F'R, so when it forms an image on the photoreceptor 10'2, the red image on the original O blends into the background. Put it away. Part 1) Due to the slit exposure, the photoreceptor l
An electrostatic latent image corresponding only to the black image on the original O is formed on O.

This electrostatic latent image is developed with a positively charged black colorant by the image forming apparatus 12 at 50C. Thus, photoreceptor I
A black visible image corresponding to the fi fi one-color image on the original 0 is obtained on the original 0.

On the other hand, the photoreceptor 20 has a structure in which photoconductive layers P1 and P2 are layered on a conductive base BS, as shown in Figure 2. The light guide multilayers PI and P2 are #
The degree is different, and when irradiating the red light body 20 (C),
Only the photoconductive layer Pl'73 is mainly made into a conductor.

Conductivity 1) There is a rectifying property for holes between the base BS and the photoconductive layer P1. Then, when primary charging of negative polarity is performed by the Charcher 21 shown in Figure 1, an electric double layer is formed via the photoconductive layer P2, as shown in Figure 2 (1). In this state, the photoconductive layer P2 is said to be charged.
When the charger 22 shown in the figure performs positive charging, the photoconductive layers P1 and P2 appear as shown in Figure 2 (...).
In reality, the two are charged in opposite directions.

The opposite directions mean that the electric double layer formed through each photoconductive layer has a +6 +6 direction, so the directions are lI\T. 2 sea urchins).

! 1・ψinterval 1 has a 200 surface 'Flj, ('', after the first charge, it is 1f property/]-12th band? After 11, it is close to O, or there is... (''゛Slightly 1 Adjust the secondary charge (in the cylinder) so that it is completely reversed.
Therefore, after secondary charging.

Let's take the surface potential of the photoreceptor. This ensures that the absolute values of the charging type 07G of each photoconductive layer are different from each other.

Continuing, the exposure (*20 is exposed to the slit ρ′i light, and this state is shown in Figure 2 (Ill>). The part M corresponding to the black image N of the original 00 is not exposed, and therefore this part The surface potential of remains at the secondary charge?rrrO potential. P1, P2) charging state (resolved, this ψ) region 1) surface potential is (J6) Meanwhile, the region corresponding to the red image R is exposed to red light, and the photoconductor 1 Pl is charged The situation is resolved and the surface potential becomes negative at this location, so eventually the photoreceptor 2
0, an electrostatic latent image corresponding to i/fi is formed only for the red image R on the original O.

Therefore, this electrostatic latent image is transferred to the developing device 23 (-1H□ 1
If the image is developed using the positively charged red toner TR (Fig. I-2), a red visible image corresponding to only the red image on the original O is obtained on the photoreceptor 20 (Fig. I-2). I
v)).

Thus, a black visible image and a red visible image are obtained on the photoreceptor 10.20, respectively.

These black and red visible images are transferred onto the recording medium S in alignment with each other.

That is, the recording medium S is conveyed from the right side of the figure 1, and the charger 31 tells the transfer belt 30 to lift it up.
As a result, the mold is statically attached to the transfer belt 30.

The transfer belt 30 conveys the recording medium while rotating counterclockwise.

The red visible image on the photoreceptor 20 first appears on the charger 32.
is transferred onto the recording medium S, and then transferred onto the photoreceptor l.
The black visible image on O is transferred by charger 33.

2 color glare 1'9 to 11! ,lJSa1Also, the recording medium S is
51'jllll' 4 and 6 (not shown) separate from the belt 3o, 2 colors of EiJ shoes, 1 elephant,''
;'U1 fixing device; 35 fixes the image and discharges it out of the device.

After the inner image transfer '4', the photoreceptors 10.20 are each cleaned of residual toner by a cleaner 13.24.

On the other hand, the transfer belt 30 is neutralized by the charger 34.

In this way, a two-color copy corresponding to the two-color original can be obtained.

1, replace the red filter FR, put a red cut filter FC into the optical path, stop the rotation of the photoconductor 2 (J'71) and the warm-up movement around the photoconductor 20, and then close the device. If you perform the belly copy process on the remaining part), the red color on the original 0
It is possible to copy a two-color black image using only one black color.

By the way, the problem is as follows. In other words, the photoreceptor 20, which has a two-layer photoconductive layer, is charged with primary and secondary charges with opposite polarities, but what will happen if an abnormality occurs in these primary and secondary charges? .

If we consider the case where the process proceeds without secondary charging for some reason, in this case, the photoreceptor 2
0 suddenly receives the image bar tip from the situation in Figures 1 and 2 (1), and as shown in Figures 3 and 2 (V), the negative polarity corresponds to G black image N and red image R on original O. An electrostatic latent image is formed, and this image is removed using red toner TR as shown in Figures 1 and 2 (
As shown in Vl), a red visible image corresponding to the black image N and the red image R is formed. Then, the black image corresponding image of the copy image obtained on the recording medium becomes a mixture of red toner and black toner, resulting in an extremely unsightly color. Instead, the red toner that forms a visible red image corresponding to the black image on the photoreceptor 2o is wasted in vain.

Conversely, what happens when the process progresses without primary charging and only secondary charging occurs?

In this case, positive electrostatic charge 1 formed on the light body 20
Since the latent image and the red toner have the same polarity, no development takes place, but if the developer is a two-component powder, the carrier charged with the opposite polarity to the toner will adhere to the photoreceptor.

A part of the gear is transferred onto the recording medium S and enters the fixing device N, causing damage to the recording medium S.

Also, some of the particles may get into the cleaner, damaging the cleaner's performance, or get between the blade and the photoconductor, damaging the photoconductor.

Japanese Patent Application Publication No. 54-5644? Using only a photoreceptor having a photoconductive layer (i.e., a two-layer process) as disclosed in No. The photoreceptor is 2 to 1 [φ is formed → 1, and this is often reversed to 2 (φ toner makes one shell image), and 1i1L, so the gear is also positive and negative. 111g, -, 1m M+': Carry'' The problem is the inefficient consumption of toner, as well as the problem of primary and secondary charging. It can also occur in some cases.

(Purpose) Therefore, the present invention can effectively prevent the occurrence of problem 17). The purpose is to provide a two-color electrophotographic copy system #.

(Structure) The present invention will be explained below. The present invention can also be applied to a two-color electrophotographic system that uses only a reflector having two layers of prism and T-bis, and can also be applied to a two-color electrophotographic method using only a reflector having two layers, or two e-photographs as shown in Fig. A.1. It can also be applied to two-color electrophotographic methods.

In any case, a photoreceptor having at least two photoconductive layers is used.

Now, the two-color electrophotographic copying apparatus of the present invention has the following features: 1. Bottle.
It has two detection means, a charging stop means for stopping primary and secondary charging, and an optical static elimination means.

The 1/10 detection means detects the zero charging current for primary charging, and the second detection means detects the charging current for secondary charging.

The charging stop means stops the power supply to each charger for primary and secondary charging when at least one of the current values detected by the detection means of iLi and J□2 differs from a set value, and stops the primary and secondary charging. Stop both.

The optical charge eliminating means prevents image exposure between the secondary charging section, that is, the section where secondary charging is performed and the developing section. , '4'+ , A
・2n detection means f)・Charging 71 by one side at the longest
Process 1) When an abnormality, that is, a difference from the set value is detected, the charged photoreceptor portion is evenly removed in a slit shape.

Hereinafter, a description will be given based on a specific implementation ψ11.

Figure A.3 shows schematically an implementation of the present invention applied to the method shown in Figure 1 (+lj f/f/difficulty, part 7 necessary for stickiness 1). Same 7] The equipment is the same as in Figure 1.1 '7) 1 layer No. 1 is used (・. Also, the parts not shown in the figure, the 5'C system, the photoreceptor 10 and its surroundings) The vessels, etc. are the same as in Figure 3.1.The bottle and figure 3 are marked with U.
[To explain the symbols that appear, E1 is the power supply for the charger 21 for primary charging, E2 is the power supply for the charger 22 for secondary charging, and E3 is the static elimination lamp as optical static elimination means. 3
The power supply for 03, code DI is ``4□ lg) ``7'') current detection circuit, code D2 is 1 year
As a detection means g) Current detection circuit, 300 is a current value discrimination circuit, 302 is a control circuit, 302 is an abnormality indicator, and M is a drive motor.

Power supplies E1, E2, E3, abnormality indicator 302. The motor M etc. are controlled by a control circuit 301.

The current detection circuits M DI and D2 detect charging currents of primary charging and secondary charging, respectively.

The current value determination circuit 300 compares the detected current values detected by the current detection circuits Di and D2 with the set values of the charging currents for primary and secondary charging, and determines whether the detected current values are different from the set values. .

The current value discrimination circuit 300 and the control circuit 301 constitute charging stopping means.

Now, how to implement the present invention will be explained with reference to Figure 4.

-4' The left half of Figure 4 shows Thailand and mink in normal condition. The primary and secondary charging control signals are generated by the control circuit 1 and charger 2 by the power supplies El and E2.
1.Controls power supply to 22. It goes without saying that the ax is standing up. Incidentally, the time T is the time of ■copy cycle.

Detection signal 1. Is l the band detected by the current detection circuits DJ and D2? ■1 There is a signal that displays the number 1 of the songs.

Now, in a case where the wire of the charger 22 for secondary charging breaks during discharge,
If we consider the case where the secondary charging is interrupted midway, the timing in case 7) is shown in the right half of Figure A'4.

1, detection 1H311'J) By the falling edge, the secondary band 1H311'J) is detected, and as a result, the control 1 circuit immediately switches between the primary and secondary 1 current control circuits. 11 signal and turn it off, and the static elimination lamp control signal is turned off. At the same time, the -e47r+display control 1j bar code is also turned off.

This results in 7 years of char for primary and secondary hypnotic sleep.
22 stops, both the primary and secondary widebands stop, and there is no abnormality indication on the abnormality indicator 302.

In addition, the static elimination wrap 303 lights up slightly, indicating that the photoconductor is abnormally charged. , Uniform 11 (One ray of light is used to remove static electricity. This causes the toner to be expended. It's a wasteful consumption.)
Adhesion is also prevented.

In general, the recording medium is already in the process of being conveyed, so the device's drive motor M17')
The operation continues as is for the duration of the copy cycle, the recording medium is ejected, and after the prescribed copying process is completed, the operation of the device is stopped. Note that the erase lamp can also be used as the static elimination wrap 303. In that case, all erase lamps are turned on in case of abnormality.

(Effects) As described above, in the two-color electrophotographic copying apparatus according to the present invention,
Toner consumption is zero due to abnormalities in primary and secondary charging,
Adhesion of carrier to the photoreceptor is prevented.

[Brief Description of the Drawings] 114□ Figures 1 and 2 are for explaining the two-color electron process, and Figures 1 and 3 are for explaining the parts necessary for explaining one embodiment of the present invention. only, schematically illustrated front view;
FIG. 4 is a timing chart for explaining the above embodiment.

Claims (1)

[Claims] Two photoconductive layers are laminated on a drum-shaped or belt-shaped conductive substrate.
On the other hand, at least a photoreceptor prepared such that the photoconductive layer is mainly a conductor is used. A two-color copying apparatus having a step of performing primary and secondary charging of opposite polarities on a light body, the detection means for detecting the charging current of the primary charging. , a total of 27] detection means for detecting the charging N current of the secondary charging, and when at least one of the current values detected by the detection means differs from the set value,
A means for stopping both primary and secondary charging is provided between the secondary charging section and the developing section, and when an abnormality in the above-mentioned charging current is detected, the part of the photoreceptor where the charging abnormality has occurred is transferred to the slit. 1. A two-color electrophotographic copying apparatus, characterized in that it has a photo-static eliminating means for uniformly irradiating the image.