JPH0438349B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an image recording device that forms a multicolor image by superimposing a plurality of toner images on an image support.
Used for electrophotography, facsimiles, laser printers, computer output, etc.

[Prior art]

In a conventional multicolor image recording apparatus, a multicolor toner image is formed on a recording paper by repeating charging, exposure, development, and transfer steps for each component color. For example, an electrostatic latent image is formed in each of the above steps using separated light of blue, green, red, etc. obtained through a color separation filter, and developed with yellow, magenta, cyan, and if necessary black toner to form toners for each color. is formed, and each color toner image is transferred onto recording paper. In this way, a plurality of toner images are superimposed on the recording paper to form a multicolor toner image, which is then sent to a fixing device and fixed by pressure or heat.

In such an image recording apparatus, in addition to forming a plurality of toner images, the recording efficiency is extremely poor because each toner image is transferred individually, and for example, the recording time is three or four times longer than that of a black and white image recording apparatus. In addition, there are problems such as the need for a transfer drum to transfer each toner image, which increases the size of the apparatus, and the difficulty in guaranteeing positional shift accuracy due to repeated operations.

In order to improve this problem, for example, in the specifications of Japanese Patent Application No. 183152/1983 and Japanese Patent Application No. 184381/1983, a plurality of toner agents are superimposed on an image support to form a multicolor toner image. An image forming apparatus has been proposed in which a fixed image is obtained by transferring the image onto recording paper and conveying it to a fixing device. In this image recording apparatus, a DC bias is applied to the developing device for obtaining a toner image to use a reversal development method, and an AC bias is applied from the second time onwards to use a non-contact development method.

The principle of image formation in the image recording apparatus described in the above specification will be explained below with reference to the flowchart shown in FIG. In FIG. 3, E is the positive surface potential applied to the surface of the photoreceptor, PH is the image exposed area of the photoreceptor,
DA is the unexposed area of the photoreceptor, Dup is the increase in potential caused by the adhesion of positive band toner to the exposed area PH during the first development, and Cup is the potential of the exposed area caused by the second charging. Indicates the increase.

The photoreceptor is uniformly charged by a scorotron charger and given a constant positive surface potential E, which decreases to near zero potential at the exposure portion PH by the first image exposure. Here, for the developing device,
By applying a positive DC bias almost close to the surface potential E and performing so-called reversal development, the positively charged toner T in the developing device is transferred to the exposed area where the potential is relatively low.
The toner particles come to adhere to the PH, and a first toner image is formed. In the area where the toner image is formed, the potential increases by Dup due to the adhesion of the positively charged toner T, but then the second charging is performed by the charger, and the potential further increases by Cup. As in the non-exposed area DA, a potential close to the initial surface potential E is obtained. Next, a second imagewise exposure is performed on the surface of the photoreceptor on which a uniform surface potential E has been obtained to form an electrostatic latent image, and a second visible image is obtained through a similar development operation. . By repeating the above process, a multicolor toner image in which a plurality of toner images are superimposed on the photoreceptor is obtained, which is transferred to recording paper and then conveyed to a fixing device and fixed. On the other hand, the photoreceptor after fixing is subjected to removal of residual charges and cleaning of residual toner, and then prepared for the next multicolor image formation.

In the image recording apparatus described in the above-mentioned specification, the transfer drum is not required and the apparatus becomes compact. In addition, when using the reversal development method, only the area to which the toner adheres needs to be exposed, and in the case of regular development, This method has the advantage that the life of the photoreceptor is extended because it is not necessary to expose the background portion without any gaps. In addition, when a non-contact development method is adopted, problems such as damage to the previous toner image and color mixing of toners resulting in disordered color balance are eliminated.

By the way, in the image forming apparatus described above, the next transfer and fixing cannot be performed until after the image support has been rotated a plurality of times to form a plurality of toner images. Therefore, it is desirable to form the plurality of toner images at high speed so that transfer and fixing can proceed quickly. However, the fixing device has a limit in increasing the linear speed due to heat capacity, and the fixing device and the conveying device attached thereto are operated at a relatively low speed, which affects the overall image forming process at a high speed. The reality is that this cannot be achieved.

[Problem that the invention seeks to solve]

The problem to be solved by the present invention is that in an image recording device that superimposes a plurality of toner images on an image support, multicolor toner images can be formed at higher speed without damaging the fixed image, and as a result, multicolor toner images can be formed at higher speed without damaging the fixed image. An object of the present invention is to provide an image recording device that can efficiently form color images.

[Measures to solve the problem]

The above problem arises when there is a charging means around the image support.
An image recording apparatus that includes an exposure means, a plurality of developing means, and a transfer means, and superimposes a multicolor toner image on the image support by multiple rotations of the image support, the multicolor toner image The linear velocity of the image support when forming the multicolor toner image is set to be higher than the linear velocity of the means for fixing the recording paper onto which the multicolor toner image is transferred, and This is achieved by an image recording apparatus characterized in that after the toner image is formed, the linear velocity of the image support is made to match the linear velocity at which the fixing means performs fixing.

Further, the above problem can be solved by disposing a charging means, an exposing means, a plurality of developing means, and a transfer means around the image support, and by multiple rotations of the image support, multiple colors are produced on the image support. An image recording device for superimposing toner images, wherein the linear velocity of the image support when forming the multicolor toner image performs fixing of the recording paper onto which the multicolor toner image is transferred. The linear velocity of the image support is set to be higher than the actual linear velocity, and the linear velocity of the image support is made to match the linear velocity at which the fixing means performs fixing during the formation of the multicolor toner image. This is achieved by an image recording device that

[Effect]

In the image recording apparatus having the above configuration, charging is performed multiple times in order to form a plurality of toner images on the image support.
Image exposure and development are repeated to form superimposed multicolor toner images. In order to speed up image formation, it is preferable that the plurality of developing devices for carrying out the development a plurality of times employ a so-called non-contact developing method in which alternating current voltage is applied to the developing devices to cause toner to fly and develop. On the other hand, the multicolor toner image is transferred onto a recording paper by a transfer device, and then transported by a conveyor and sent to a fixing device to be fixed. The speed is set to be a few times lower than the linear speed of the image support on which the toner image is formed.

Therefore, before the multicolor toner image reaches the fixing device, it is necessary to match the linear velocity of the fixing device at some point. Examples of the method for matching the linear velocities include the following cases.

(Case 1) After a plurality of toner images are superimposed on the image support to form a multicolor toner image, the linear speed of the image support is reduced to match the linear speed of the fixing device. . Thereafter, the multicolor toner image is transferred onto the recording paper by a transfer device, and transported to a fixing device by a conveyor.

(Case 2), the linear velocity of the image support is reduced to match the linear velocity of the fixing device before the overlapping of the plurality of toner images on the image support is completed. For example, after the three-color toner images of yellow, magenta, and cyan are superimposed, the linear speed of the image support is reduced to match the linear speed of the fixing device.
Next, a black toner image is formed on the image support at a reduced linear speed, and is transferred and fixed at the same linear speed.

As mentioned above, a multicolor toner image is formed at high speed by superimposing a plurality of toner images on an image support.
The linear speed is switched to a linear speed suitable for fixing at appropriate times before and after the formation of the multicolor toner image. Therefore, not only the efficiency of forming multicolor images is greatly improved, but also the desired fixation is achieved, so that high-quality images can be obtained under high efficiency.

〔Example〕

The present invention will be explained below with reference to Examples, but the embodiments of the present invention are not limited thereto.

Example 1 Figures 1 and 2 are diagrams explaining this example, and 1 is a drum-shaped selenium photoreceptor with a circumferential speed of 480 mm/sec.
is rotated in the direction of the arrow. Reference numeral 2 denotes a scorotron charger, and the charger 2 uniformly charges the surface of the photoreceptor 1 to +600V. Reference numeral 3 denotes a known helium-neon laser device, from which a laser beam 4 having a dot density of 16 dots/mm is modulated by an external yellow image signal and is irradiated onto the photoreceptor 1 to perform image exposure. to form an electrostatic charge image. This electrostatic charge image is first developed by a developing device 5 containing yellow toner to form a yellow toner image. Next, photoreceptor 1
After the surface is neutralized as necessary, it is recharged to +600V by the scorotron charger 2 and imagewise exposed to laser light 4 modulated by a magenta signal to form an electrostatic charge image. This electrostatic charge image is transferred to a second image by a developing device 6 containing magenta toner.
Repeated development is performed to form a magenta toner image superimposed on the yellow toner image. Similarly, a cyan toner image is formed after image exposure by laser light based on the cyan image signal and black image signal, and third and fourth development by the developing device 7 containing cyan toner and the developing device 8 containing black toner. , black toner images are formed in a superimposed manner to obtain a multicolor toner image.

Next, in this embodiment, before the multicolor toner image is transferred onto the recording paper P, the photoreceptor 1 is moved at a circumferential speed of 120 mm/sec.
The speed is reduced to match the linear speed of the fixing device. In this way, the multicolor toner image is transferred onto the recording paper P conveyed at 120 mm/sec by the transfer electrode 11, and separated from the photoreceptor 1 by the separation electrode 12.
The image is conveyed by a conveyor 13 that moves at 120 mm/sec, and is heated and fixed by a fixing device 14. On the other hand, after the transfer, the photoreceptor 1 is neutralized by a pre-cleaning static eliminator 15, and then residual toner is removed by a cleaning blade 16, which was released during toner image formation, and is prepared for the next image formation.

Next, the structure and operation of the developing device used in the image recording apparatus shown in FIG. 1 will be explained based on FIG. 2. Since the developing devices 5, 6, 7, and 8 basically have the same structure, the developing device 5 is shown in FIG. 2 as a representative example. The developing device 5 contains 50% by weight of magnetite dispersed in the resin with an average particle size of 20 μm.
m, magnetization 30 emu/g, resistivity 10 ¹⁴ Ωcm or more carrier, average particle size of styrene-acrylic resin with 10 parts by weight of benzidine derivative as yellow pigment and positive charge control nigrosine dye as charge control agent. 25% by weight of 10μm non-magnetic toner
A mixed developer D is stored therein.

The sleeve 20 of the developing device 5 is made of an aluminum cylinder with a diameter of 30 mm, and is rotated in the direction of arrow G at a speed of 50 rpm. The magnetic body 21 has six N and S magnetic poles, has a magnetic flux density of 1000 Gauss, and is rotated in the direction of arrow F at a speed of 2000 rpm. The developer D is conveyed by the sleeve 20 and the magnet 21, and is regulated by the film thickness regulating blade 22 to a thickness of 0.5
A developer layer with a thickness of mm is formed. After this developer layer develops an electrostatic charge image in a development area E where the gap between the sleeve 20 and the photoreceptor 1 is 0.8 mm, it is scraped off by a doctor blade 23 and collected in a developer reservoir 25. This developer reservoir has a stirrer 2.
4 is provided to uniformly mix the developer. When the developer in the developer reservoir 25 runs out of toner, the toner T in the hopper 26 is replenished in a fixed quantity by the replenishment roller 27.

28 is a power source for applying DC bias and AC bias to the sleeve, and 29 is a protective resistor. In the developing device 5, +500V is applied as a DC bias, and +500V is applied as an AC bias.
2KV is applied at 2KHz. By applying such an AC bias voltage, non-contact development is achieved, and disturbance of the color balance of a multicolor image is prevented. Furthermore, since the development time is controlled simply by turning on and off the alternating current bias, unnecessary development is prevented, toner is saved, and wear and tear on the photoreceptor is prevented. In addition, particularly in the case of a non-contact method, high-speed development becomes possible, which has the advantage of achieving high-speed development when forming multicolor toner images.

Although the developing devices 6, 7, and 8 have the same structure as described above, the toner contained therein and the bias voltage applied to the sleeve 20 are different. In the developing device 6, a toner containing Rhodamine B as a magenta pigment is used, and a DC bias of +500V and an AC bias of 1.8KV at 2KHz are applied. In developing devices 7 and 8, toner containing copper phthalocyanine as a cyan pigment and toner containing carbon black as a black pigment are used, and the bias voltages are both +500V DC bias and 2KHz.
An AC bias of 1.8KV was used.

As described above, a multicolor toner image is formed at 480
Since multicolor images are formed at a high linear velocity of mm/sec, an image recording apparatus is provided in which a multicolor image can be recorded at approximately the same speed as a normal black and white image, and which also has excellent fixing performance. In addition, toner images of each color formed using a reversal development method and a non-contact development method are superimposed on the photoreceptor 1 to form a multicolor toner image, and this is transferred to recording paper at once, which improves image quality and color. A well-balanced multicolor image can be obtained.

〔Effect of the invention〕

As explained above, in an image recording apparatus that forms a multicolor toner image by superimposing a plurality of toner images on an image support, the multicolor toner image is formed at high speed, while fixing is performed at an appropriate rate according to heat capacity. By making it possible to record a multicolor image at a high speed, the efficiency of recording a multicolor image can be increased, and desired fixation can be achieved and a high quality image can be obtained. Furthermore, since a plurality of toner images are transferred onto the recording paper at the same time, the apparatus can be made compact, and since there is no displacement of the toner images, a clear multicolor image can be obtained. Moreover, by preferably using a non-contact developing method, many effects can be achieved, such as achieving even faster production of multicolor toner images.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a main part of an image recording apparatus for explaining an embodiment, FIG. 2 is a cross-sectional view of a developing device of the image recording apparatus shown in FIG. 1, and FIG. 3 is for explaining the image forming principle of the image recording apparatus. Showing a flowchart. 1... Drum-shaped selenium photoreceptor, 2... Scorotron charger, 5, 6, 7, 8... Developing device, 9...
...Pre-transfer charger, 10...Pre-transfer static elimination lamp, 1
DESCRIPTION OF SYMBOLS 1... Transfer electrode, 12... Separation electrode, 13... Transport body, 14... Fixing device, 20... Sleeve, 2
1... Magnet body, 22... Film thickness regulating blade, 28
...Bias power supply, E...Development area, D...Developer, T...Toner, P...Recording paper.

Claims (1)

[Scope of Claims] 1. A charging device, an exposing device, a plurality of developing devices, and a transfer device are disposed around an image support, and multiple rotations of the image support result in multiple rotations on the image support. An image recording device for superimposing color toner images, wherein the linear velocity of the image support when forming the multicolor toner image is such that the linear velocity of the image support is faster than the fixing means for fixing the recording paper onto which the multicolor toner image is transferred. The linear velocity of the image support is set to be higher than the linear velocity when performing fixing, and after the multicolor toner image is formed, the linear velocity of the image support is made to match the linear velocity when fixing is performed by the fixing means. An image recording device characterized by: 2. A charging means, an exposure means, a plurality of developing means, and a transfer means are arranged around the image support, and multicolor toner images are superimposed on the image support by multiple rotations of the image support. The image recording device is characterized in that the linear velocity of the image support when forming the multicolor toner image is higher than the linear velocity of the means for fixing the recording paper onto which the multicolor toner image is transferred. An image recording apparatus characterized in that the linear velocity of the image support body is set to be large while forming the multicolor toner image, and the linear velocity of the image support body is made to match the linear velocity when the fixing means performs fixing.