JPH0228864B2 - - Google Patents

Description

[Detailed description of the invention]

[Object of the Invention] (Industrial Application Field) The present invention relates to a multicolor recording device that can be used in electrophotography to obtain multicolor recorded images. (Prior Art) Multicolor recording technology using electrophotography has a long history, and various methods have been proposed and disclosed. Among these, technologies that have recently received particular attention include methods that use light-emitting elements such as laser oscillators and light-emitting diode (hereinafter referred to as LED) arrays, or methods that use liquid crystal or Some devices use an optical system that writes digitized optical information using an optical switching element using the Farade effect. The reason why these technologies are considered to be effective for multicolor recording is the first
Furthermore, there is no longer a restriction on process speed caused by a mismatch between the light intensity of each color information obtained by color separation of an original and the spectral sensitivity of the photoreceptor, which has been considered one of the major technical difficulties in multicolor electrophotography. Second
Additionally, various S/N improvements are possible through electrical processing. Thirdly, it is possible to perform many applied processes by linking with a computer, such as electrical image processing such as image information editing. In electrophotographic devices that use these methods of writing digitized image information onto photoreceptors,
Generally, reversal development is performed to visualize the portion irradiated with the exposure beam. This reduces the load on the laser oscillator and LED that serve as the light source, and
This is because the burden on the accuracy of the scanning optical system can be reduced. The basic method of multicolor electrophotography is to repeat the charging, image exposure, and development steps as many times as the number of colors to be used. The first method is to arrange devices for charging, image exposure, and development processes in the number of required colors, and the first method is to arrange only developing devices in the number of colors to be used, and the charging and image exposure devices are arranged in a photosensitive manner. It is broadly divided into the second method, which uses repeated rotation of the body. The first method requires a large device, but the recording time is short, and it is a method that has high expectations from a practical standpoint. Normally, when reproducing colors, various intermediate colors can be obtained by adjusting the mixing ratio of three primary colors (cyan, magenta, and yellow), but controlling these adjustments is relatively difficult. The reason for this is that when a second toner image is formed on the first toner image once formed on the photoreceptor, when exposure is performed to control the adhesion amount, the corona-charged toner image is damaged by the electrostatic charge on the photoreceptor. This is because the phenomenon of loss of binding force and scattering becomes noticeable. This causes smearing of character images, etc., making it unusable, and many devices generally avoid this by using the second method described above. However, as described above, it is necessary to solve these problems in order to realize a practical multicolor recording device. (Problems to be Solved by the Invention) The present invention has been made to solve various problems related to the reproduction of intermediate colors by conventional exposure control. It is an object of the present invention to provide a multi-color recording device capable of reproducing intermediate colors in a short time without using a multi-color recording device and using inexpensive means. [Structure of the Invention] (Means for Solving the Problems) The present invention provides a multicolor recording device that forms a multicolor recorded image on an image carrier by repeating charging, image exposure, and development steps multiple times. , a recharging means is provided which recharges only a specific area of the image carrier to a predetermined potential in the second and subsequent charging steps, and whose output is selectively controlled. (Function) By selectively controlling the output of the recharging means that performs the second and subsequent charging steps, and by configuring the recharging means to recharge only a specific area of the image carrier, It becomes possible to reproduce intermediate colors in a short time using inexpensive means without using the conventional method of reproducing intermediate colors by controlling the exposure amount. (Example) Hereinafter, an example of the present invention will be described with reference to the drawings. FIG. 1 shows a multicolor recording apparatus according to the present invention. That is, 1 is a main body of the apparatus, and approximately in the center of the main body 1, a photoreceptor (image carrier) 2 of, for example, a drum-shaped selenium-tellurium alloy is rotatably disposed. The photoreceptor 2 is rotated (at a circumferential speed of, for example, 160 [ mm/s]). And photoreceptor 2
Around the 1st charging corona device 4, 1st LED
Array 5, first developing device 6, second charging corona device 7, second LED array 8, second developing device 9, third
Charging corona device 10, third LED array 11, third developing device 12, pre-transfer corona device 13, transfer corona device 14, peeling guide 15, static elimination lamp 16, and fur brush cleaning device 17
are arranged in this order along the rotation direction Z of the photoreceptor 2. Here, the first charging corona device 4 is
A desired voltage (for example, a voltage of about 6.5 [KV]) is applied, and after the photoconductor 2 starts rotating, the photoconductor 2
Uniformly charge the surface to, for example, 1000 [V]. The second and third charging corona devices 7 and 10 are activated or deactivated by either an instruction from an external device or a manual operation from the operation panel 18. 1st to 3rd LED array 5, 8, 11
The light-emitting point is scan-controlled in accordance with an image signal from an external device, so that the surface of the photoreceptor 2 is imagewise exposed and a desired signal is recorded as an electrostatic latent image. The first to third developing devices 6, 9, and 12 contain cyan toner, magenta toner, and yellow toner, respectively, and reversely develop the electrostatic latent image on the surface of the photoreceptor 2 (i.e., the first or 3rd LED
The exposed areas of arrays 5, 8, and 11 are developed). In the lower right side of the figure of the main body 1, there is an insertion slot 20 of a cassette 19 for storing recording paper, a cassette holder 21, and a view of the inside of the cassette 19 inserted into the cassette holder 21 through the insertion opening 20. A paper feed roller 22 that feeds out the recording paper one sheet at a time by rolling contact with the recording paper, and a transfer corona device 14 that transfers the recording paper sent out by the paper feeding roller 22 to the photoconductor 2 in synchronization with the rotation of the photoconductor 2. A paper feed section 25 is provided, which includes a pair of registration rollers 23 and a guide plate 24, which feed the paper to a transfer position between the two. In addition, in the upper right side of the figure of the main body 1, there is a paper ejection port 26 for ejecting recording paper on which an image has been recorded to the outside of the main body 1, and a paper ejection port 26 that protrudes from the paper ejection port 26 to the outside of the main body 1. A paper ejection section 29 is provided, which includes a paper ejection tray 27 for receiving recording paper, and a pair of paper ejection rollers 28 disposed inside the main body 1 of the paper ejection port 26. Further, a fixing device 30 is provided adjacent to the paper ejection roller 28, and this fixing device 30 and the peeling guide 1
A conveyor belt 32 is stretched between a pair of rollers 31 in order to convey the recording paper peeled off from the photoreceptor 2 by a peeling guide 15 to a fixing device 30. In the figure, numeral 33 is a high-voltage power supply for the first to third charging corona devices 4, 7, and 10, and numeral 34 is a printed circuit board in which a processing circuit for processing signals from the image input section 3 is incorporated. . In such a configuration, when the photoreceptor 2 is rotated in the direction of the arrow Z shown in the figure, the surface of the photoreceptor 2 is uniformly charged by the first charging corona device 4, and then is charged by the first LED array 5. Image exposed to photoreceptor 2
An electrostatic latent image is formed on the surface. This electrostatic latent image is developed by the first developing device 6, and cyan toner is adhered thereto. After development by the first developing device 6, the photoconductor 2 is recharged by the second charging corona device 7, or imagewise exposed by the second LED array 8 without being recharged to form an electrostatic latent image. be done. This electrostatic latent image is developed by the second developing device 9, and magenta toner is attached thereto. After development by the second developing device 9, the photoreceptor 2 is further recharged by the third charging corona device 10, or imagewise exposed by the third LED array 11 without being recharged to form an electrostatic latent image. It is formed. This electrostatic latent image is developed by the third developing device 12 and yellow toner is adhered thereto. After development by the third developing device 12, the photoreceptor 2 to which the cyan toner, magenta toner, and yellow toner are attached is returned to a uniform charge amount by the pre-transfer corona device 13. On the other hand, in synchronization with such rotation of the photoreceptor 2,
A recording paper is supplied to a transfer position by the paper feeding section 25 and brought into contact with the photoreceptor 2, and the toner images of the respective colors are transferred onto the recording paper by the transfer corona device 14. After the transfer, the recording paper is peeled off from the surface of the photoreceptor 2 by a peeling guide 15 and conveyed to a fixing device 30 by a conveyor belt 32, where the transferred toner image is fixed. After fixing, the recording paper is discharged onto a paper discharge tray 27 via a paper discharge port 26 by a paper discharge roller 28. On the other hand, the photoreceptor 2 from which the recording paper has been peeled is irradiated with light by the charge removal lamp 16 to remove the charge, and then cleaned by the fur brush cleaning device 17 and prepared for the next recording. Next, the first to third charging corona devices 4, 7, 10, the first to third LED arrays 5, 8, 11, and the first to third developing devices 6, 9, which are the main parts of the present invention. , 12 will be explained in more detail. As mentioned above, the photoreceptor 2 is first charged uniformly by the first charging corona device 4, and then the photoreceptor 2 is charged uniformly by the first charging corona device 4.
An electrostatic latent image is formed by image exposure by the 1LED array 5, and this electrostatic latent image is further developed in reverse by the first developing device 6, and cyan toner is adhered thereto. After the reversal development by the first developing device 6, the second developing device 6
The charging corona device 7 is selectively activated or deactivated by either an instruction from an external device or a manual operation from the operation panel 18. FIG. 2a shows the surface potential V of the photoreceptor 2 after reversal development by the first developing device 6, and when the second charging corona device 7 is in operation, the photoreceptor 2 is It is charged again to a desired potential (for example, the original potential V _p by the first charging corona device 4).
That is, as shown in FIG. 2b, a portion A (40 indicates cyan toner)
The potential V _R is returned to the original potential V _p by the second charging corona device 7 . On the other hand, the portion B that was not subjected to the first image exposure (the portion on which the electrostatic latent image was not formed) hardly changed even when recharging by the second charging corona device 7, and remained at the original potential V. _p is maintained. Then, when imagewise exposed by the second LED array 8, the surface potential of the photoreceptor 2 is selectively attenuated (electrostatic potential image is formed). Therefore, when the second developing device 9 develops the image, magenta toner is applied to the area where the electrostatic latent image is formed (the area where the surface potential of the photoconductor 2 is attenuated more than V _p ). is attached. On the other hand, when the second belt corona device 7 is inactive, the photoreceptor 2 is exposed imagewise by the second LED array 8 while maintaining the surface potential state shown in FIG. 2a. Therefore, in the photoreceptor 2, the portion where the electrostatic latent image is formed by image exposure other than the portion A to which the cyan toner 40 is attached is in a potential state lower than V _p , and the second developing device 9, magenta toner is attached to the portions to which the cyan toner 40 is attached and to the portions where the electrostatic latent image is formed. That is, in this embodiment, if recharging is not performed by the second charging corona device 7, the developed color on the photoreceptor 2 will be two colors: blue and magenta, which are a mixture of cyan and magenta. When the photoreceptor 2 becomes colored and is recharged, the developed colors on the photoreceptor 2 become two colors: a single color of cyan and a single color of magenta. Similarly, even when the third charging corona device 10 is in operation or inactive, the third LED array 11 and the third developing device 12 perform image exposure and
A developing step is performed. Therefore, in this embodiment, the second and third
By controlling the operation or non-operation of the charging corona devices 7, 10, and also controlling the operation of the first to third developing devices 6, 9, 12,
Seven colors obtained from the three colors as shown in FIG. 3 can be combined, and as a result, multicolor recording consisting of any three of these seven colors is possible. The alphanumeric characters in the figure were used as symbols corresponding to the respective colors. Here, examples of recorded colors obtained by activating (on) or inactivating (off) the first to third charging corona devices 4, 7, and 10 are shown in the table below.

[Table] In addition to the table above, it is also possible to change the order of the colors of each developing device, and to enable (on) or inactive (off) the developing devices themselves, resulting in various color combinations being reproduced. Needless to say, it is set. Also, the colors used are cyan,
It is not necessary to be limited to magenta and yellow, and by selecting and using various colors in advance, it is possible to obtain a color reproduction range that more closely matches the purpose. Note that these process sequences are controlled by the operation panel 18 or an external device (for example, a computer).
An instruction signal from the image input unit 3 connected to the image input unit 3 is programmed by these processing circuits (built into the printed circuit board 34) and sent to the second and third charging corona devices 7 and 10. It is designed to control the operation of the connected high-voltage power supply 33, and the relationship between the content of these electrical controls and color reproduction is programmed in advance. Next, the charging device 51 used as the second and third charging corona devices 7 and 10 will be described in detail with reference to FIG. 4. As shown in FIGS. 2a and 2b, this charging device 51 charges the potential difference generated by the first image exposure by the first LED array 5 to the non-exposed area B (where an electrostatic latent image is formed) where the potential is high. (parts that are missing)
is held as it is, and exposed area A with low potential is
(The part where the electrostatic latent image is formed) has a selective charging function to return it to the same potential as the non-exposed part B.
It is composed of a conductive cylindrical shield 52 and a corona electrode 53 provided within the cylindrical shield 52, and the corona electrode 53 is connected to the high voltage power supply 3.
Connected to 3. In addition, 54 in the figure is the high voltage power supply 33.
This is a switching control section that performs switching control. The output of the high voltage power supply 33 is, for example, an AC voltage having a frequency of about 400 to 1000 Hz, and has a voltage waveform as shown in _FIG . It can be adjusted independently along with the peak value V _AC . By using such a charging device 51 as the second charging corona device 7, as shown in FIG. _R returns to the original potential _Vp , for example, as shown by the dashed line _in FIG. Charging only a specific area (portion A), so-called selective charging, is achieved by increasing the output voltage V _AC of the high voltage power supply 33,
This is possible by appropriately combining the values of V _DC and adjusting the voltage to a predetermined potential. In this example, V _AC is approximately 7 [KV], V _DC is approximately 1 [KV], and V _p is 1000 [V] and V _R is 150 [V]. There is. Furthermore, as the second and third charging corona devices 7 and 10, not only the charging device 51 shown in FIG. 4 but also a charging device 55 as shown in FIG. 6, for example, can be used. This charging device 55 includes a conductive shield 56 and a 2
This is a scorotron charging device consisting of a book corona electrode 57 and a conductive mesh grid 58 provided at the discharge opening of the shield 56. Then, a predetermined DC voltage is applied to the grid 58 from the DC power supply 59, a corona generating voltage is applied to the corona electrode 57 from the high voltage power supply 60, and the applied voltage value is adjusted in the same manner as in the above method to selectively charge the grid. It is possible to do this. Next, the first to third developing devices 6, 9, and 12 used in this embodiment will be explained. Generally known developing devices can be used as the first to third developing devices 6, 9, and 12, but
If new toner is exchanged when reproducing the unfixed toner image on the photoreceptor 2,
Since troubles due to color mixture occur in the recorded image or in the developing device, a preferred method is required that does not cause color mixture. Further, the developing devices used as the first to third developing devices 6, 9, and 12 have slightly different structures depending on their mounting positions, but the basic elements are the same. FIG. 7 shows the first to third developing devices 6, 9, 12.
This figure shows an example of a developing device used as a developing device.
That is, 71 is a casing, and this casing 71 has an opening 72 at a portion facing the photoreceptor 2 . A portion of the housing 71 is exposed through an opening 72, and is placed in a non-contact state with the photoreceptor 2, for example, while maintaining a development distance of 100 to 400 [μm] and facing the photoreceptor 2 closely. An electrically conductive cylindrical roll (developing roll) 73 and fur brushes 74 and 75 which are brought into rotational contact with the developing roll 73 are arranged.
Further, the other end of an elastic blade 76, one end of which is in contact with the developing roll 73, is supported on the inner wall near the opening 72 of the housing 71. Developing roll 73
The fur brushes 74 and 75 are rotationally driven by a motor (not shown), and the developing roll 73
A developing bias voltage is applied from a bias power supply 77. Note that toner 78 is housed in the housing 71. In such a configuration, when the developing roll 73 and the fur brushes 74 and 75 are rotated, the toner 78 is rubbed by the fur brushes 74 and 75, and is frictionally charged and transferred to the developing roll 7.
3, forming a thin toner layer. The formed toner thin layer is regulated to an appropriate thickness by an elastic blade 76 and conveyed to a developing area. The thin toner layer that has reached the developing area is ejected onto the surface of the photoreceptor 2 from the portion where it reaches the ejection starting electric field. That is, development is performed by an electric field formed by the electrostatic latent image potential of the photoreceptor 2 and the development bias voltage. Since this developing device has no mechanical contact with the photoreceptor 2 as described above,
Mixed colors and recorded images are transferred to the next developing process (second developing device 9
or the developing process by the third developing device 12), and is suitable for multicolor development. As explained above, according to the above embodiment, a plurality of developing devices using different color toners arranged around the photoreceptor are provided with recharging devices capable of output control, and the outputs of these recharging devices are selected. By controlling the image forming apparatus, it is possible to selectively obtain a monochrome record of each developing device and a different intermediate color record by combining the monochrome colors of each developing device in a short time. Therefore, it is possible to record more color reproductions than the number of developing devices without using optical means, and it is also possible to obtain a product with excellent functionality at a low price and without changing the structure. It should be noted that the present invention is not limited to the above-mentioned embodiments, and the reproducibility can be changed depending on, for example, the number and color of developing devices, and whether or not image exposure is performed at each station. Further, in the embodiment described above, a multicolor recorded image can be obtained by one rotation of the photoreceptor, but the present invention is not limited to this. May be transcribed. Furthermore, it goes without saying that the recharging device does not have to take only the two values of activation (on) and non-activation (off), but can also strengthen or weaken its output value within a range that does not cause any problems. . [Effects of the Invention] As detailed above, according to the present invention, a multicolor recording is possible that can reproduce intermediate colors in a short time using inexpensive means without using the conventional method of reproducing intermediate colors by controlling the exposure amount. equipment can be provided.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention, in which Fig. 1 is a longitudinal sectional front view of a multicolor recording device, Fig. 2 is a drawing explaining the action of the recharging means, and Fig. 3 is a drawing explaining color combinations. Fig. 4 is a block diagram of the recharging means, Fig. 5 is an output voltage waveform diagram of the recharging means in Fig. 4, Fig. 6 is another block diagram of the recharging means, and Fig. 7 is a diagram of the developing means. FIG. 2... Photoreceptor (image carrier), 4... First charging corona device (charging means), 5, 8, 11... First
or third LED array (image exposure means), 7, 10
...Second and third charging corona devices (recharging means),
6, 9, 12...first to third developing devices (developing means).

Claims (1)

[Scope of Claims] 1. In a multicolor recording device that forms a multicolor recorded image on an image carrier by repeating charging, image exposure, and development steps multiple times, the image carrier is a recharging means for recharging only a specific area of the image carrier to a predetermined potential and whose output is selectively controlled; means for selectively switching between a first mode and a second mode for forming a mixed color recorded image formed by combining these monochromatic recorded images, corresponding to the mode selected by the means;
A multicolor recording device comprising: means for forming a monochrome or mixed color recorded image on the image carrier. 2. Claim 1, wherein the recharging means is an eccentric AC corona charging device.
The multicolor recording device described in Section 1. 3. The multicolor recording device according to claim 1, wherein the recharging means is a scorotron charging device. 4. Any one of claims 1 to 3, characterized in that it is equipped with a plurality of image exposure means and development means for performing an image exposure step and a development step, and the operations thereof are selectively controlled. The described multicolor recording device.