JPS6239402Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic apparatus, and more particularly to an electrophotographic apparatus that can switch between two types of copying modes: two-color copying and monochrome copying.

Conventionally, various methods for multicolor copying and two-color copying have been proposed. For example, as in JP-A No. 51-146832, primary charging, irradiation of a light image that blocks the chromatic colors to be reproduced on the original, secondary charging with the opposite polarity to the primary charging, irradiation of a chromatic light image to be reproduced, There is a method of obtaining a two-color copy by sequentially performing the steps of developing one predetermined color, irradiating white light, and developing other colors.

The present invention provides a device that can easily switch between two-color copying and single-color copying in one device, whereas conventional two-color copying or multi-color copying and monochrome copying, such as black copying, were performed separately. is intended to provide.

In conventional two-color or multicolor copying, a filter is always installed in the optical path to emit an optical image that blocks the light of one chromatic color of the original. The present invention has achieved the above object by creating a structure that allows the filter to be moved between the optical path and outside the optical path without permanently installing the filter in the optical path.

The details of the present invention will be described with reference to embodiments shown in the drawings.

In the figure, a photoconductor 1 having an insulating layer provided on a photoconductive layer, for example a photoconductor drum, is adjacent to a primary charger 2, a secondary charger, and a secondary charger sequentially in the direction of movement of the photoconductor 1, for example in the rotation direction of the photoconductor drum 1. A container 3, an exposure light source 4, and a developing device 5 are arranged.

The secondary charger 3 is disposed in the optical path of a commonly used optical system (not shown) that exposes and irradiates the photoreceptor 1 with a light image of a document. Therefore, irradiation of the photoreceptor 1 with a light image and charging by the secondary charger 3 can be performed simultaneously at the same location.

The secondary charger 3 includes a filter 6 that is movable between a position where the optical path is blocked and a position where the optical path is opened.
is located. In the example shown in the figure, filter 6
consists of two filter parts 6a and 6b, which are fixed to rotatably supported shafts 7 and 8, respectively,
Gears 9 and 10 are fixed to the shafts 7 and 8, respectively. The gears 9 and 10 mesh with each other, and when one of the shafts 9 or 10 rotates, the filter parts 6a and 6b open and close synchronously. In the open position, both filter portions 6a and 6b are parallel to the optical path, as shown by the chain lines, and do not impede the passage of light. The exposure optical path is divided into two optical paths at filter portions 6a and 6b. A thread 11 is fixed to one of the shafts 9 and 10, one end of which is fixed to the thread 11, and the other end of the wound thread 12 is connected to a switching lever 13. The switching lever 13 is supported by a support shaft 14 so as to be tiltable between a first mode position shown by a solid line and a second mode position shown by a chain line. Switching lever 13
The spring 15 is in a state where tension is applied to the thread 12.
is empowered by.

Two-color copying is performed in the first mode position;
In the mode position, monochrome copying is performed. When the switching lever 13 is in the first mode position shown by the solid line, the filter 6 is in a state of blocking the optical path as shown by the solid line, and when the switching lever 13 is moved to the second mode position, the filter 6 is in the state of blocking the optical path shown by the chain line. Rotate to open position.

The switching lever 13 operates the switch 16 in either the first mode position or the second mode position, in the example shown in the figure, in the second mode position, and the wire in the rear half of the secondary charger 3 is controlled by an appropriate control circuit. 19b is operated to the closed state. The wire 19a in the front half of the secondary charger 3 is applied with a polarity opposite to that of the primary charger or an AC voltage regardless of the operation of the switching lever 13, but the wire 19b in the rear half is applied when the switch 18 is closed. Only when this occurs, the high voltage generator 18 applies a high voltage of opposite polarity to the primary charging or alternating current to generate corona discharge.

The developing device 5 has developing sections 5a and 5b for each color, for example, in two-color development, the developing section 5a has a red toner and the developing section 5b has a black toner. The exposure light source 4 has developing sections 5a and 5.
placed between b.

When the switching lever 13 is moved to the second mode position and a command for monochrome copying is sent by the switch 16 to the developing device through the control device, the developing sections other than the developing section 5b containing black toner, for example, become inactive. For example, in dry development, the magnetic brushes other than the developing section 5b are moved so as not to come into contact with the surface of the photoreceptor 1, or the rotation of the magnetic brushes is stopped, and in the case of wet development, the magnetic brushes other than the developing section 5b are moved so as not to touch the surface of the photoreceptor 1. The developing roll is separated from the photoreceptor 1 to prevent developer from being supplied to the photoreceptor 1.

The operation of this device will be explained.

In the case of monochrome copying, the switching lever 13 is moved to the second mode position shown by the chain line. The movement of the switching lever 13 is transmitted to the bobbin 11 via the thread 12.
is rotated. The gears 9 and 1 are rotated by the rotation of the bobbin winder 11.
0, the filters 6a, 6b are moved to the second mode position shown by the dashed line.

The photoreceptor 1, which rotates in the direction of the arrow in response to a copy command, is primarily charged by a primary charger 2. Figure 2a
As shown in the figure, the surface of the insulating layer 1a of the photoreceptor 1 is charged with a primary charge (positive polarity in the example shown), and the photoconductive layer 1
A charge having a polarity opposite to that of the insulating layer 1a (negative in the figure) is induced in b.

The primarily charged photoreceptor 1 is exposed to an optical image beam by an exposure optical system that passes through a secondary charger 3 .
At this time, the switching lever 13 is operating the switch 16, and voltage is applied to the rear wire of the secondary charger 3 by closing the switching switch 17. Therefore, to the secondary charger 3, a high voltage of opposite polarity or alternating current is applied to the first half wire 19a and the second half wire 19b. Note that voltage is not applied to the secondary charger 3 simultaneously with the movement of the switching lever 13, but is applied through a relay circuit in accordance with a predetermined sequence as the photoreceptor moves.
The secondary charger 3 is set so that a voltage is applied simultaneously with the photoimage exposure.

As shown in FIG. 2b, in the photoreceptor 1, the resistance of the photoconductive layer decreases in the portion corresponding to the white area A of the original, and the negative charge induced in the photoconductive layer escapes, causing a positive primary charge on the surface of the insulating layer. The charge is eliminated by secondary reverse polarity charging. Although the resistance of the photoconductive layer 1b slightly decreases and the negative charges escape in a portion corresponding to the red area B of the original, some negative charges still remain in the photoconductive layer 1b. The potential on the surface of the insulating layer has a value close to zero. Since no light comes from the original to the black area C of the original, the resistance of the photoconductive layer does not decrease and negative charges are retained, and the potential on the surface of the insulating layer has a value close to zero.

The photoreceptor 1 on which the latent optical image is formed is transferred to the developing device 5
Developed by At this time, the switching lever 13 operates the switch 16, and the developing section 5a containing toner of a color other than the desired color, for example, the red developing section 5a, is inactive, so that the photoreceptor 1 is not developed by the developing section 5a. As shown in FIG. 2C, negative charges that are not restrained by the surface charges of the insulating layer escape from the photoconductive layer as shown in FIG. 2C. A positive surface potential is generated in areas B and C of the photoreceptor, and black toner of negative polarity adheres to the areas B and C of the photoreceptor due to development in the developing section 5b.

The developed photoreceptor is transferred to the transfer paper 2 at the transfer position.
0 under the action of the transfer charger 21, then the static electricity is removed by the static eliminator 22, the cleaning device 23 performs cleaning, and the process from the primary charging is repeated again.

Next, in the case of two-color copying, the switching lever 13 is moved to the first mode position shown by the solid line, and the filter 6
a and 6b are set to block the optical path in the secondary charger 3. At this time, the switching lever 13
The switch 16 is deactivated, and both the developing sections 5a and 5b are set to the operational state. The rear wire 19b of the secondary charger 3 is connected to the changeover switch 17.
No voltage is applied due to the opening of the terminal.

In response to a copy command, the photoreceptor 1 is charged by the primary charger 2 as shown in FIG. 3a, as in the case of monochrome copying.

The primary charged photoreceptor 1 is exposed to a light image through a filter 6, for example, a filter 6a that blocks the transmission of red color, for example, a cyan filter, and at the same time, the front half wire 19a of the secondary charger 3 is connected to the primary charger 2. Charging is performed with reverse polarity or alternating voltage.

In the photoreceptor 1, as shown in FIG. 3B, the charge of the photoconductive layer in the area A escapes, and the primary charge on the surface of the insulating layer disappears due to the secondary charge. Furthermore, since the photoconductive layer in regions B and C is shielded from light, the resistance of the photoconductive layer does not decrease, and the potential on the surface of the insulating layer approaches zero while the induced negative charge in the photoconductive layer is maintained.

The photoreceptor 1 is then exposed to a light image through a filter 6b, such as a red filter, which passes a desired color, such as red. At this time, it is not charged.

In the photoreceptor 1, as shown in FIG. 3c, regions A and C are similar to those in FIG. The rest run away. As a result, only region B has a positive surface potential. This photoreceptor 1
is developed with red toner in the developing section 5a of the developing device 5 as shown in FIG. 3d. Since the surface potential of area C is zero, red toner does not adhere to area C.

The red-developed photoreceptor 1 is exposed to light by the exposure light source 4, and among the negative charges on the photoconductive layer in the region C, charges that are not restrained by the positive charges on the surface of the insulating layer escape, and the surface potential of the photoreceptor becomes positive.

The area C of the photoreceptor 1 is developed with black toner by the developing section 5b of the developing device 5, as shown in FIG. 3e. A two-color image is thus produced.

The image on the photoreceptor 1 is transferred to the transfer paper 20 at the transfer position.
After that, the image is transferred to a single color, and then static electricity is removed, cleaned, and charged again in the same way as in the case of a single color.

With this invention, the simple structure of providing a structure that moves between a position where the optical path of the filter is blocked and a position where it is not blocked, and a structure that switches a part of the developing section between an operating state and a non-operating state makes it possible to produce monochromatic images. It is now possible to switch between copying and two-color copying.

According to the present invention, since the filter can be switched and moved, good image quality can be obtained both in monochrome copying and in two-color copying. In addition, if the light is not passed through a filter, the amount of exposure will be large under the same illumination conditions, so by switching the filter, the moving speed of the optical system and photoreceptor can be increased. It is now possible to increase the copy speed compared to copy mode 1. If you do not change the copy speed, you can increase the aperture value (lower value) of the copying lens to narrow down the aperture, which increases the depth of focus, making it possible to clearly copy even solid objects with irregularities on the original in the second copy mode. can.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory diagram of the main parts of the copying apparatus according to the present invention, FIG. 2 is a diagram showing changes in the charge of the photoreceptor in the case of monochrome copying, and a to c are diagrams showing the copying process in order, and FIG. FIG. 3 is a diagram showing changes in the charge on the photoreceptor in the case of two-color copying, and a to e are diagrams showing the respective copying steps in order. 1... Photoreceptor, 2... Primary charger, 3... Secondary charger, 4... Exposure light source, 5... Development device,
5a, 5b...Developing section, 6...Filter, 6
a, 6b... Filter part, 19a... Front wire, 19b... Rear wire, 20... Transfer paper,
21...Transfer charger, 23...Cleaning.

Claims (1)

[Scope of utility model registration request] a primary charger, an exposure optical system, a secondary charger, a developing device having a developing section for each color, an exposure light source provided between the developing sections for each color, and a transfer means; In an electrophotographic apparatus capable of two-color copying on a photoreceptor having a cleaning means and an insulating layer provided on a photoconductive layer, the secondary charger is divided into two parts, a front wire and a rear wire. a secondary charger is disposed in the optical path of the exposure optical system; a filter of the exposure optical system is movably disposed between a position where the optical path is blocked and a position where it is not blocked; The filter is formed into two filter parts corresponding to the division of the secondary charger, and the optical path is divided into two according to the two filter parts, and one of the divided parts of the secondary charger is divided into two parts. An electrophotographic device capable of switching between monochrome copying and two-color copying, characterized in that high voltage application is controlled on and off according to the movement of a filter portion of a wire.