JPS60200266A - Image forming device - Google Patents

Abstract

PURPOSE:To enable simple changeover of a copying mode by exchanging the cartridge of an image forming device provided with a developing device and exposing part meeting the mode. CONSTITUTION:A catridge of the made for copying a positive original picture image to a positive image is exchanged with a cartridge 13' having a developing device 17' and an exposing part 44' for an N-P mode in the processing state in the N-P mode for copying the negative picture to the positive image after setting the film of said picture. The exposing part 44' has no function for blank exposing and is provided with a stationary light shielding plate 37 between an image exposing path and an exposing lamp to prevent the turning rund of lamp light. A changeover switch is held changed over to th N-P mode side. If copying is made after setting in the above-mentioned way, blank exposing is not made as the plate 37 is held closed and since the switch is held set to the N-P mode side, the polarity of the voltage impressed to an electrifier for transfer changes over and the quantity of light from a light source for image exposing is so controlled as to meet the N-P mode.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus, such as a microfilm league printer, in which copying modes can be easily switched.

A microfilm league printer enlarges and projects an original image taken on a microfilm onto a screen for observation, and also obtains a hard copy of the image using electrophotography. The original image captured on microfilm may be a positive image or a negative image. In either case, it is difficult to see the copied hard copy unless it is a positive image, so it is preferable to copy it into a positive image, whether it is a positive original or a negative original. P-P
mode) and mode for copying from a negative original image to a positive image (
There is no device that allows the user to freely and easily select the NP mode.

By the way, in image forming apparatuses that apply electrophotography, such as league printers, in pp mode development, in which charged charges remain on the unexposed portions of the photoreceptor, charged charges are removed. In areas where the developer toner remains, the developing toner adheres to the photoreceptor, so that unnecessary areas are developed and the toner is wasted.

In order to prevent this, so-called blank exposure, in which uniform light is applied to the photoreceptor, is performed except during image exposure. On the other hand, in N-P mode development (reversal development), toner adheres to the exposed surface of the photoconductor, but toner does not adhere to areas that are not exposed to light and have residual charges, so blank exposure is unnecessary. Therefore, it is necessary to perform blank fog light in the P-P mode and to avoid blank exposure when switching to the N-P mode.

The present invention has been made in view of the above, and an object of the present invention is to provide an image forming apparatus that can switch between PP mode and NP mode with an extremely simple configuration.

In order to achieve this object, the present invention forms an electrostatic latent image by imagewise exposure on a charged photoreceptor, and develops the electrostatic latent image with a toner charged with a polarity opposite to that of the electrostatic latent image. A mode for copying to a positive image.

In an image forming apparatus capable of selecting a mode in which a toner charged with the same polarity as the charged charge of the electrostatic latent image is developed and a positive image is copied from a negative original image, at least a developing device of the toner with the opposite polarity or the same is used. Replacing an image forming device cartridge that is equipped with a polar toner developer and an exposure section that has a blank exposure function that irradiates the photoreceptor with uniform light when the image is not exposed, or an exposure section that does not have this function. The image forming apparatus is characterized in that the copying mode can be selected by doing so.

Examples of the present invention will be described in detail below.

FIG. 1 shows an image forming apparatus to which the present invention can be applied.

This figure shows a schematic configuration of a league printer.

The apparatus shown in the figure includes a film illumination light source 1, a condenser lens 2, a field lens 3. Film F, projection lens 5
is the projection part. A mirror 7117' and a screen 8 are used to observe the original image on the film F in the league section. In addition, 7' is a number matching mirror for adjusting the front and back of the image. The image light from the projection unit is sent to the scanning mirror lO・1
1 and is also projected onto the copying section. The copying section is equipped with process equipment for electrophotographic image formation.

13 is a process equipment cartridge, which has a blank exposure section 4;
I am enjoying 4. 20 is a transfer charger, 21 is a copy paper cassette, and 22 is a register roller.

23.6232 is a paper feed roller, and 25 is a fixing device.

FIG. 2 shows details of the main parts of this league printer, and shows the state when a positive original film is set and processed in the P-P mode.

The cartridge 13 can be inserted and removed in the front direction along a rail 28 attached to the chassis of the printer main body. Inside it, there is a photoreceptor 15. Corona charger 16, developer 17
, a cleaner 18 is attached integrally or detachably. Since this cartridge 13 performs PP mode development, the charging polarity of the toner supplied by the developing device 17 is opposite to that of the corona charger 16. The blank exposure section 44 includes a lamp 19, a shutter member 30, a solenoid 32, a rotating light shielding plate 37, and a spring 39.
etc. are attached to the housing. 46 is an optical path opening for image exposure. The shutter member 30 is supported on the main body chassis by a rotating shaft 31, and is attached by a spring 39 when the scanning mirror 10/11 moves in the opposite direction to the scanning direction or when it is outside the image exposure scanning area such as in a league state. It is held at the position shown by the solid line so as to close the image exposure path.

The lower surface of the shutter member 30 is a reflective surface. Also 1
During image exposure scanning, the shutter member 30 is rotated by energization of the solenoid 32, and is stopped by a stopper 35 at a position indicated by a chain line. This opens the image exposure path and also
Close the blank exposure path from 9. This energization is performed depending on the length of the copy paper. Reference numeral 37 denotes a rotating light-shielding plate, which is supported on the main body chassis by a shaft 38, opened to open a blank exposure path in the P-P mode, and supported by a stopper 35. Note that the light from the lamp 19 passes through the pre-exposure window 42 and hits the photoreceptor 15 after image formation, thereby extinguishing any remaining charges. The rotating light shielding plate 37 is open in the vicinity facing the window 42 so as not to prevent the light from the lamp 19 from going toward M42. 47048 is a copy paper guide plate, and P is copy paper.

FIG. 5 is an external perspective view of the cartridge 13. A protrusion 49 for operating a changeover switch 40 attached to the main body of the device is fixed at the outer inner part. Changeover switch 40
is for switching the image forming process conditions depending on the copy mode. Note that 52 is a socket cap of the lamp 19, and 53 is a power supply connector for the lamp 19 and the solenoid 32.

FIG. 4 is an operating circuit block diagram of process conditions that are changed by the switch 40 when changing the mode.

In the figure, reference numeral 60 denotes a circuit which generates one signal in either the P-P mode or the N-P mode by being switched by the switch 40. 62 is a high-voltage power supply for the transfer charger 20, and has a polarity suitable for transferring developing toner in the PP mode. 63 is also a high-voltage power supply, but it has a polarity suitable for transferring developing toner in the N-P mode, and has a polarity opposite to that of the high-voltage power supply 62. Reference numeral 61 denotes a high voltage relay, which relays electricity to either the high voltage power source 62 or the high voltage power source 63 to the transfer charger 20 in response to a signal from the circuit 6o.

Reference numeral 65 denotes a circuit for controlling the amount of light from the lamp, which controls the light source 1 to have an appropriate exposure performance in either the P-P mode or the N-P mode in response to a signal from the circuit 60. 66 is an external variable circuit that adjusts the light source l according to the density Φ contrast of the original film image.
A signal for changing the amount of light is sent to the circuit 65.

In such a league printer, when projecting onto the screen 8, the scanning mirror to@tt is at a home position H away from the optical path from the projection lens 5 to the screen 8. When making a copy, it is driven by a drive source (not shown) to advance into the optical path, and while scanning the original image on the film F, projects it onto the rotating photoreceptor 15. Note that the scanning speed at this time is the same as the rotational speed of the photoreceptor 15. Also,
The scanning mirrors 10 and 11 are orthogonal to each other, and 0 is the intersection point, starting from the home position H, and moving from 0□ to 02
The original image is scanned at a constant speed. The light from the scanning mirror 11 passes through the opening 46 of the blank exposure section 44 and is irradiated onto the photoreceptor 15 .

In the copying section, copies are made in P-P mode according to the normal electrophotographic process. At this time, the light from the pre-exposure lamp 19 passes through the window 42 and irradiates the photoreceptor 15, and at the same time, the one-turn light shielding plate 37 opens a blank exposure path, so the shutter member 30 at the position shown by the solid line in FIG. Photoreceptor 1 hits the reflective surface of
It is reflected in the direction of 5 and blank exposure is performed. Since the changeover switch 40 is pressed by the protrusion 49, it is switched to the P-P mode. Therefore, a voltage with a polarity suitable for the PP mode is applied to the transfer charger 20. Further, the light intensity of the lamp 1 is also controlled to match the P-P mode.

Next, a description will be given of when a negative original film is set and processed in the NP mode. The state at this time is shown in FIG. To perform processing in the NP mode, the cartridge 13 having the developing device 17 in the PP mode is replaced with a cartridge 13 having the developing device 17' in the NP mode. The exposure section 44 does not have a blank exposure function, and a fixed light shielding plate 37 is provided between the image exposure path and the pre-exposure lamp 19 to prevent the light from the lamp 19 from going around. Also cartridge 13
Since there is no protrusion provided on the outside of the switch 40 for operating the changeover switch 40, the switch 40 is switched to the NP mode. The rest of the structure inside the Naori-Trilli 13' is the same as the cartridge 13.

With the copying section set up in this way, you can easily
According to the process, the negative original image is copied in N-P mode. At this time, since the rotary light shielding plate 37 is closed, the light from the pre-exposure lamp 19 is not blank exposed even when the shutter 30 is at the position indicated by the solid line in the figure.
has been switched to the N-P mode side, so the transfer charger 2
The applied voltage polarity with respect to 0 is switched, and the light amount of the image exposure light source 1 is controlled to be suitable for the NP mode.

As explained above, according to the present invention, P-P mode, N
- Simply by replacing and attaching/detaching a cartridge suitable for the P mode, blank exposure can be performed as needed, and appropriate process conditions can be selected. The switching mechanism has an extremely simple structure. By making it into a cartridge, parts can be placed with high precision, and in the event of a failure, the entire cartridge can be replaced, providing excellent serviceability. Furthermore, since the exposure section is integrated with the cartridge, it can be easily installed and there is no chance of incorrect installation.

Naori-Trilli may be equipped with an electric circuit that matches each process condition.The pre-exposure lamp should be installed on the main body of the device and used in both P-P mode and N-P mode. Can be done.

In addition, the cartridge may be configured so that the color of the developing toner can be selected as appropriate at the same time as the P-P mode and N-P mode are changed.In this case, the color of the copy can be changed at the same time as the mode selection, increasing versatility. becomes more widespread.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a league printer to which the present invention is applicable, Fig. 2 is an enlarged view of the main parts of a league printer to which the present invention is applied, and Fig. 3 is the same diagram as above when the cartridge is replaced.
FIG. 4 is a block diagram of an operating circuit under process conditions, and FIG. 5 is an external perspective view of the cartridge. 13/13' is an image forming device cartridge, 17/17
' is a developing device, 19 is a lamp, 3o is a shutter member, 37
4o is a changeover switch, and 44 and 44' are exposure parts.

Claims (1)

[Claims] (1) A mode in which an electrostatic latent image is formed by imagewise exposure on a charged photoreceptor, and the electrostatic latent image is developed with a toner charged with a polarity opposite to that of the electrostatic latent image, thereby copying a positive original image into a positive image; Developing a toner charged to the same polarity as the electrostatic latent image,
In an image forming apparatus capable of selecting a mode for copying a positive image from a negative original image, at least a developing device using toner of opposite polarity or a developing device using toner of the same polarity, and uniform light when the image is not exposed. By replacing the cartridge of the image forming device, which is equipped with an exposure section having a blank exposure function for irradiating the photoreceptor with a blank exposure function, or an exposure section without this function. An image forming apparatus characterized in that the copy mode can be selected.