JPS60147754A - Color printer for multicolor printing - Google Patents

Abstract

PURPOSE:To increase the adhering force of toner to an electrostatic latent image and to obtain a printed picture having stable density by forming an electrostatic latent image with developing contrast potential approximately similar to the allowable potential of a photosensitive body in each toner development of each color. CONSTITUTION:A toner feeding rool 22 and a developing roll 23 are arranged in a developing device 30b having a toner feeding port 24. The developing roll 23 is set up contactlessly with a photosensitive drum 5 and the roll 23 is connected to a power supply terminal having prescribed potential V0. The drum 5 has exposing parts of black, red and blue on positions A, B, C respectively. The exposing parts A-C are exposed by receiving optical beams 1 modulated by black, red and blue picture signals through an optical system constituted by a lens system, a rotary polyhedral mirror 4, an exposing mirror 20, and reflecting mirrors 19a- 19d. An electrostatic latent image with the developing contrast potential approximately similar to the allowable potential of the photosensitive body is formed in each toner development of each color, so that the adhering force of the toner is increased and a printed picture with stable density can be obtained.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a multicolor shicolor printer that achieves high speed by obtaining a multicolor shicolor print with one rotation of a photoreceptor. The present invention relates to a multicolor color printer that can increase the potential difference in a non-image area (hereinafter referred to as development contrast potential) to the allowable potential of a photoreceptor.

(Background Art) For example, a printer having a structure shown in FIG. 1(a) has been proposed as a printer capable of producing multicolor prints by rotating a photosensitive drum once in order to increase printing speed. This multicolor color printer has a scanning system including a lens 51 that sends scanning light 50 to a photosensitive drum 5 after scanning a document, and a photosensitive drum 5 that is exposed to the scanning light 50. (A charged corotron 9 in →, a red filter 10 that receives white light from a white light lamp 52 and transmits only red light, a charged corotron 11 in (g), and develops an electrostatic latent image on the photosensitive drum 5. a black toner developing section 12 and a red toner developing section 13;
A pre-transfer corotron 14 (c) that adjusts the polarity of the toner to facilitate transfer, a transfer corotron 15 that transfers the image onto the paper 7, and a cleaner 16 that removes the toner after transfer are provided. . A paper feed tray 8 for feeding paper to the transfer section 6 is provided at the front stage of the transfer corotron 15.
A transport belt 17 and a fixing section 18 are provided downstream of the transfer section 6. The photosensitive drum 5 is shown in Figure 1 (=)
As shown in (1), it is composed of three layers, the upper layer is a non-red sensitive material 5a that transmits red light and is not sensitive to red light, the middle layer is a red sensitive material 5b that is sensitive to red light, and the lower layer is a non-red sensitive material 5a that is sensitive to red light. For example, the substrate 5c is made of aluminum.

In the above configuration, the operation will be explained based on FIG. 1(B).As a first step, as shown in FIG. Charging processing is performed in (c) using the charging corotron 9, and after the above charging processing, when white light A from the white light lamp 52 is irradiated onto the surface of the photosensitive drum 50 through the red filter 10, the white light transmitted through the red filter 10- is The red light component passes through the non-red sensitive material 5a and makes the red sensitive material 5b conductive. As a result, the photosensitive drum 5
The same amount of charge (→ is attracted to the red sensitive material 5b part of the red sensitive material 5b by the charge of (→) on the surface. As a second step,
As shown in Figure (b) (3), the surface of the photoreceptor 5 is charged with a charging corotron 11 (→) at a voltage weaker than that of the corotron 9 described above.

As a result, the charge of (→ on the surface of the photosensitive drum 5 is
Since the amount of charge corresponding to the amount of charge disappears, in order to maintain a balance between the amount of charge of (→ on the surface of the photosensitive drum 5 and the amount of charge of (→) in the red sensitive material 5b, the amount of charge of 0 on the surface of the photosensitive drum 5 Charges (→) are collected in the substrate 5c of the photosensitive drum 5 by the amount that is insufficient.As a third step, as shown in FIG. 1 (b) (4)
As shown in FIG.
1. Expose with scanning light C based on the red image and white light C in the non-image area. As a result, as shown in FIG. 1 (→ (5)), when viewed from the surface of the photosensitive drum 50 while the area receiving the scanning light a remains unexposed, an electric field based on the charges in (→ In the area exposed by the scanning light, the red sensitive material 5b becomes conductive and remains on the substrate 5c. The same amount of charge (→) as the charge (→) in the red sensitive material 5b remains on the photosensitive material 5a.As a result, when viewed from the surface of the photosensitive drum 5, an electric field based on the charge (→) acts. In the exposed area, both the sensitive materials 5a and 5b become conductive (→(
→ All charges disappear. As the fourth stage, the developing section 1
According to 2.13, as shown in Figure 1 (b) (6),
When the corresponding parts of the black toner 12a charged to (-) and the red toner i3a charged to (1) are developed, the parts exposed to the scanning light a will be (→
The black toner 12a of (→) adheres to the area exposed by the scanning light, and the red toner 13g of (→) adheres to the area exposed by the scanning light.As a fifth step, as shown in FIG. Adjust the polarity using Transfer Corotro/14 ((
+) red toner 13a changes to ().

The developed toners 12a and 13a whose polarity has been adjusted by the pre-transfer 7 arcotron 14 are transferred by the transfer corotron 15 at the transfer section 6, and then conveyed by the transport belt 17 and fixed by the fixing section 18. be discharged.

However, according to this multicolor printing shicolor printer, as shown in FIG.
Volts) so the polarity is set to be opposite, so
The black and red development conolast potentials can only be raised to a level that is approximately half the allowable potential (Vl - Vs) of the photosensitive drum, and therefore the adhesion force of the toner to the electrostatic latent image cannot be increased. First, it has the disadvantage that a printed image with stable density cannot be obtained.

(Objects and Structure of the Present Invention) The present invention has been made in view of the above, and in order to increase the adhesion of toner to an electrostatic latent image and obtain a stable printed image, toner of each color is used. The present invention provides a multicolor color printer that forms an electrostatic latent image with a development contrast potential approximately close to the permissible potential of a photoreceptor for each development.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.

(Example) Figure 2 shows an example of the present invention, and the same parts as in Figure 1 (A) are indicated by the same reference numerals, so duplicate explanation will be omitted, but modulation is performed according to one image signal. a laser oscillator 2 that oscillates the light beam 1, a lens 3 that focuses the light beam 1, and a rotating polygon mirror 4 that diffuses the light beam 1 in the scanning direction.
A photosensitive drum 5 is provided below which is exposed to the light beam 1. Around the photosensitive drum 5 are a charging corotron 9& for developing black toner, a focusing toner developing device 30a, and a charging corotron 9b for developing red 7 toner.
A red toner developing machine 30b, a charging corotron 9C for developing blue toner, and a blue toner developing machine 30e are provided, and among the three developing machines, the red toner developing machine 30b,
The blue toner developing device 30e has a non-contact developing structure. As shown in FIG. 3, the non-contact developing method has a configuration in which a developing machine 30b having a toner supply port 24 is provided with a toner supply roll 22 and a developing roll 23. are in a non-contact state with a predetermined gap between them, and the developing roll 23 is connected to the positive terminal of a power source having a predetermined potential Vo.

The photosensitive drum 5 has black, red, and blue exposed areas at positions A, B, and O, respectively. Each exposure section A, B, 0 is a laser oscillator 2
Modulated by black, red, and blue image signals output from
The light is exposed by receiving the light through an optical system configured as shown in FIG. The laser oscillator 2 and the exposure mirror 20 are controlled by a control section 31.

In the above configuration, the operation is shown in Fig. 4 (1) to (9).
5(A) to 5(F), in the first step, as shown in FIG. 4(1), the photosensitive drum 5 is transferred to the black toner charging corotron 9a (→ charging Potential■
Charge it to 1 (Figure 5 (a)). In the second step, as shown in FIG. 4(2), exposure is performed using a light beam 1a modulated with a black image signal.

The electric charge (g) of the black image portion E on the photosensitive drum 5 is eliminated, and the potential is lowered to {circle around (2)}. As a third step, as shown in FIG. 4(3), the potential of the black toner developing device 30a is
The black toner 12a charged to E from the developing roll of
It adheres to the parts (Fig. 5 (b)). In the fourth step, as shown in FIG. 4(4), the photosensitive drum 5 is charged to the band 11L position (g) 1 by the red toner charging corotron 9b (FIG. 5(c)). As the fifth step, Figure 4 (
5), the light beam 1 modulated with the red image signal
By b! 7 exposure, and the red image portion G on the photosensitive drum 5←
) is dissipated and the potential is lowered to k V x.

As a sixth step, as shown in FIG. 4 (6), the red toner 12b charged to (G) from the developing roll 23 (FIG. 3) with the potential V of the red toner developing device 30b adheres to the 0 part. (see Figure 5)). 7th stage and Figure 4 (7)
As shown in ← by charging corotron 9c for blue toner.
) to a charging potential ■l (Figure 5 (e)). 8th
As a step, as shown in FIG. 4 (8), exposure is performed by a light beam IC modulated by the blue image signal, and the electric charge (G) of the blue image signal portion H on the photosensitive drum 5 disappears, resulting in a potential of 2
decrease to. In the ninth step, as shown in FIG. 4(9), the blue toner 12c charged to (G) from the developing roll of the K toner developing device 30a, which has a potential of V, adheres to the H portion. Note that area F remains as a non-image subcommittee. As a result of repeating charging, R'8 light, and development as described above, the maximum potential (VB-V2) allowed by the photosensitive drum 5 can be used as the development contrast of each color. Also.

Since the red toner developing machine 30b and the blue toner developing machine 30c employ a non-contact developing system, it is possible to prevent toner peeling due to contact between the developing roll 23 and the photosensitive drum 5. Furthermore, in the case of the present invention, since all the toners of each color are charged to the same polarity, polarity adjustment using a britransfer corotron is not necessary.

(Effects of the Invention) As explained above, according to the multicolor color printer according to the present invention, an electrostatic latent image with a development contrast potential approximately approximate to the allowable potential of the photoconductor is formed each time each color toner is developed. This increases the adhesion of the toner to the electrostatic latent image.

Printed images with stable density can be obtained.

[Brief explanation of drawings]

An explanatory diagram showing the printing process of one printer and two, Figure 1 (
C) is an explanatory diagram showing the contrast potential for each color toner in a conventional multicolor color printer, Figure 2 is an explanatory diagram of the structure of a multicolor color printer according to the present invention, and Figure 3 is a developing machine using a non-contact developing method. 4(1)-(9) are explanatory diagrams showing the printing process of the multi-color printer of the present invention, and FIGS. 5(A)-(9).
5) is an explanatory diagram showing the contrast potential for each color toner in each step of FIG. 4. Explanation of symbols 1...Light beam, 2...Laser oscillator, 4...Rotating polygon mirror, 9m, 9b, 9c...Charged corotron,
19... Reflection mirror, 20... Exposure mirror. 30a, 30b, 30c... developing machines. Patent applicant Fuji Xerox Co., Ltd. Agent Patent attorney Shin Matsubara 2 Patent attorney Kiyoshi Muraki Patent attorney Hei 1) Yudo Tadashi Patent attorney Atsushi Ueshima - Patent attorney Hitoshi Suzuki Figure 1 C-in (No. Figure 5

Claims (1)

[Scope of Claims] A plurality of charging means arranged according to the number of colors of the multicolor printing sheet, and a plurality of charging means provided correspondingly to the plurality of charging means, modulated by each color signal of the multicolor printing sheet, with a multiplication beam. a plurality of exposure means for forming an electrostatic latent image corresponding to each color by exposure; and a plurality of developers provided corresponding to the plurality of exposure means, respectively, for developing the electrostatic latent image with a corresponding color toner. means, wherein the band 1 means charges the photoreceptor with a potential substantially close to the allowable potential thereof, and the exposing means charges the photoreceptor with a developing contrast potential substantially close to the allowable potential by exposure with the light beam. A multicolor color printer characterized by forming an electrostatic latent image