JPS6157964A - Electrophotographic copying and printer device - Google Patents

Abstract

PURPOSE:To obtain images of high quality in the copy mode as well as the print mode by deflecting positively the overall electrification polarity of a toner to the side suitable for development in the print mode. CONSTITUTION:A bias voltage higher than that in the copy mode is applied to a developing roll 24 by a bias power source 30 to stick a toner 36 having a positive polarity to an exposed part, which has hardly an electric charge, without sticking the toner to an electrified part 32 on a photosensitive body 10, thereby performing reversal development. In this case, a one-component magnetic toner whose overall electrification polarity is deflected to the electrification polarity side of the toner contributed to development in the print mode is used. When the print mode is selected, a reversal exposed image of a picture signal 20 is formed on the photosensitive body 10, which is electrified uniformly by an electrifier 12, by an optical image scanner 18 for printer. Next, reversal development is performed while applying a bias voltage approximately equal to that of the electrified part on the photosensitive body, which is not subjected to reversal exposure, to a developing roll 24 by the developing bias power source 30 for printer.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an electrophotographic copying printer having a copying surface and a printer function. I do.

Conventional technology In recent years, electrophotographic processes have been used to develop copying exposure devices and laser scanning devices for irradiating the surface of a charged photoreceptor with light (<Q) that corresponds to the image of a document such as a general publication. ,
For example, an electrophotographic copying printer device having two optical image input systems, such as a liquid crystal screttering device and an LED array, such as an optical image scanning device for a printer for irradiating a photoreceptor recording area in accordance with an image signal, has been proposed in 1995, for example. -195265.

In the copy mode, normal development is normally performed, but in the print mode, it is preferable to perform reversal development in which toner is attached to the exposed areas (bright areas) of the photoreceptor. One of the reasons for this is that if normal image exposure is performed using an optical image scanning device for a printer and then normal development is performed, there is a risk of staining the background of the image due to uneven light irradiation. In most cases even in type copy printers, forward development is carried out in the copy mode, and reverse development is carried out in the print mode.

Problems to be Solved by the Invention In conventional electrophotographic copy printer devices, there was a problem in that the print image obtained in the print mode was less likely to be 80 degrees than the copy image obtained in the copy mode. .

The reasons for this are (1) Optical image scanning Z for printers.
1 semiconductor lede is 780 to 800 μm, 1. The EDr is 600 to 700t1m and -19 (longer wavelength side than the sensitivity range of the D-m photoreceptor), (2) the optical image is scanned with fine dots to obtain high resolution image quality. (3) In order to obtain a certain degree of scanning speed, although it is also related to resolution, 10~
100~11-(7) It is thought that there is a loss due to modulating the light at a high speed of 7, and it is difficult to give a sufficient amount of exposure to the photoreceptor in the bearint mode compared to the exposure in the copy mode, so the latent image This is thought to be due to the fact that the electrostatic contrast is smaller in the copy mode and in the relative bearint mode.

As roughly described above, it is preferable to perform forward development in copy mode and reverse development in print mode.
Although such a method has actually been carried out, a preferred normal/reversible developing system has not been proposed so far.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide an electrophotographic copying printer that can produce high-quality images in the print mode in the copy mode.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a copying exposure device for irradiating the surface of a charged photoreceptor with a light image corresponding to the image of an original. , an optical image scanning device for printers that irradiates the surface of a photoreceptor charged according to an image signal, and a one-component magnetic toner that visualizes the electrostatic latent image formed on the surface of the photoreceptor. In an electrophotographic copying printer device, which is equipped with a developing unit to be used and a power supply device that applies developing biases of different potentials in a copy mode and a print mode, and performs forward development in the copy mode and reverse development in the print mode. Provided is a Nobuko photocopy printer device characterized in that the overall charging polarity of the one-component magnetic toner is biased to the side that matches the polarity of the toner adhering to the surface of the photoreceptor during a print mode.

In this way, by actively biasing the overall charging polarity of the toner to the side that is suitable for development in print mode,
In copy mode, you can obtain high-quality images in print mode.

The present invention will be explained in detail below with reference to the drawings. Referring first to FIG. 2, this figure is a graph showing the relationship between development potential and development density.

The development @ potential is indicated by the difference between the latent image potential (18) and the development bias potential V8, where (V-V8) is a positive region indicates normal development, and a negative region indicates reverse development. In this case, of course, a P-type photoconductor with a positive latent image potential on the photoconductor is used, and if an N-type photoconductor with a negative charging polarity is used, normal rotation and reversal will be reversed. Become.

Hereinafter, in the present invention tfAta, unless otherwise specified, a P-type photoreceptor having positive charging polarity will be explained.

The graph in FIG. 2(a) shows that one-component magnetic toner has MJ m
This shows the development curve when the toner itself is almost completely uncharged, or even if the toner is insulating, the charging polarity inside the toner is balanced and the overall toner charge is almost zero. The shape is almost symmetrical in the inversion region and the inversion region, and the slope of the rise is almost the same. The graph in (b) shows the development curve when the one-component magnetic toner has high resistance or insulation with a volume resistivity of 1012 Ωcm or more, and its charge polarity is biased towards the positive polarity side. , the development curve has a steeper slope in the reversal region where positive polarity toner contributes to development than in the normal rotation region. On the contrary, the graph (C) shows a case where the toner has a charge polarity that is biased toward the negative polarity as a whole, and the development curve around 1 is large in the normal rotation region where the negative polarity toner contributes to development.

Next, referring to FIG. 1, this figure shows the state of adhesion of toner on a photoreceptor having a positive latent image charge, (
a) shows the adhesion state of λ toner in normal development in the copy mode, and <1)) shows the adhesion state of toner in reverse development in the print mode.

Referring to FIG. 1(a), the electrostatic latent image 3 on the photoreceptor 10h
2 is developed while applying a bias voltage to the developing roll 24 by a bias power supply 28, and a negative toner 34 adheres to the latent image 32. Referring to FIG. 1(b), reversal development in the print mode is shown, and by applying a larger bias voltage to the developing roll 24 by the bias power supply 30 than in the copy mode, the charged portion on the photoreceptor 10 is 3
In No. 2, no toner was attached, but a positive polarity toner F-36 was attached to the exposed area, which had almost no charge, to perform C reversal development. In this case, the overall charge polarity of the toner used is biased toward the side of the charge polarity of the toner that contributes to development during print mode in order to particularly improve the image quality in print mode. I did it.
Since a component magnetic toner is used, a toner having a development curve shown in FIG. 2 (1)) is used. Using toner having such general charging polarity, normal development with a gentle slope of the development curve is performed in the copy mode, and reverse development with a steep slope of the development curve is performed in the print mode. This is a major feature of the present invention.

Next, referring to FIG. 3, an electrophotographic copy printer to which the principles of the present invention are applied will be described.

In FIG. 3, numeral 12 is a charging device that charges the photoreceptor 10, and numeral 14 is a charging device that charges the photoreceptor 10 in a manner similar to
A copying exposure device 18 is used in print mode to form an image on the photoreceptor 10, which forms an image corresponding to the image signal 2o.
This is an optical image scanning device for a printer formed on the top. Current t! J
The A device 22 uses one-component magnetic toner,
The current roll 24 is rotatably supported by a housing (not shown). The developing roll 24 is connected to a developing bias power source 28 for nine copies or a developing bias power source 11iI30 for a printer through a developing bias switching device 26, and a developing bias suitable for each is applied. The bias voltage in print mode is usually higher than the bias voltage in copy mode. 38 transfers the developed image on the photoreceptor to transfer paper 401. : A transfer device for transferring, and 42 is a fixing device. 44 is a cleaning device for cleaning the residual toner image on the photoreceptor.

Operation The operation of the electrophotographic copy printer of the present invention shown as an example in FIG. 3 will be explained below. When the copy mode is selected, the copy exposure device 14 exposes the original 16 onto the photoreceptor 10, which is uniformly charged by the charging device 12, and an electrostatic latent image corresponding to the original is placed on the photoreceptor. It is formed.

This electrostatic latent image is developed by the TA image roll 24 while applying a bias voltage from the bias power supply 28, and the negatively charged toner adheres to the positively charged latent image portion on the photoreceptor, resulting in the electrostatic latent image. The river legend will be held. The developed image is then transferred onto a transfer paper 40 by a transfer device 38, and the transferred image on the transfer paper 40 is fixed by a fixing device 42 to become a permanent image. - The residual toner image on the photoreceptor is clear (product device 4)
4, and one copy cycle is completed.

When the print mode is selected, an inverted exposure image of the image signal 20 is formed by the printer optical image scanning device 18 on the photoreceptor 10 that has been uniformly charged by the charging device 12. Next, reversal development is performed while applying a bias voltage comparable to that of the charged portion on the photoreceptor that has not been subjected to reversal exposure to the developing roll 24 from the printer developing bias power supply 30. When developing is performed while applying a bias voltage in this manner, the positively charged IC toner adheres to the reversely exposed portion of the photoreceptor, and the static IPIa on the photoreceptor is reversely developed. The toner image on the photoreceptor that has been reversely developed by the developing device 22 is transferred to a transfer sheet 40 by a transfer device 38, and the toner image on the transfer sheet is then fixed by a fixing device 42 to become a permanent image. The Zanuma toner image on the photoreceptor is cleaned by a cleaning device 44, completing one print cycle.

EXAMPLES Specific examples will be explained below in order to clarify the characteristics of the present invention and confirm its effects.

Using a one-component magnetic toner consisting of 451 parts of a binder resin made of a polar oligomer containing an amino group and a styrene polymer, 0.8 parts by weight of nigrosine as a charging agent, and 55 parts by weight of magnetite as a magnetic powder, An electrostatic latent image on a 5IB-Te photoreceptor used for positive electrode charging was developed. The fact that this toner has overall positive charging characteristics means that the thickness of the toner on the installed developing roll is approximately 0.5 cm.
It was confirmed that the Nn toner spikes had a potential of about +120V. In normal rotation development in copy mode, v3-v
A transfer density of 1.2 on the Tokiso paper with 8 = so ○■ is obtained, and in reversal development in print mode, the same 1.2 is obtained by 1σ at the transfer m degree when V - V8 = -450V, and a positive Images with sufficiently high 'cJ degrees could be obtained in both transfer development and reversal development.

In the above section 2, we have explained the photoreceptor used for positive polarity charging, but when using a photoreceptor used for negative polarity charging such as an organic photoreceptor, the charging polarity of the toner should be changed to negative polarity as a whole. I need to let you investigate. In this case, the binder resin is a well-known styrene polymer, vinyl polymer, polyester, etc., and the magnetic powder is magnetite, etc. Furthermore, carbon black, silica, etc. are used as a charging agent.

Effects of the Invention The present invention biases the overall charging polarity of the one-component magnetic toner to the side that matches the polarity of the toner adhering to the surface of the photoreceptor during print mode, so that the following effects can be achieved. .

(1) In copy mode, gradation is good and a wide variety of originals such as photographs and halftones can be reproduced. (2
) In the print mode, a clear print image with a high 8n degree and no fog can be obtained.

(3) The output of the optical image scanning device for printers can be reduced.
(4) High-speed printing is possible without using a special high-sensitivity photoreceptor. (5) A copy printer device with good image quality suitable for both copying and printing is realized.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the toner adhesion state on the photoreceptor according to the present invention, (a) shows the toner adhesion state in normal rotation development in the copy mode, and (b) shows the toner adhesion state in the print mode. It shows the state of toner adhesion during reversal development. FIG. 2 is a graph showing the relationship between the development potential and the development density. (a) shows the case where the toner charge is almost zero overall, and (b) shows the case where the charge polarity of the toner is overall positive. (C) shows a case where the charged polarity of the toner is generally biased towards the negative polarity side. FIG. 3 is a schematic diagram of an electrophotographic copying printer utilizing the principles of the present invention. 10: Sensitive light rest 14: Exposure device for copying 18: Optical image scanning device for printer 22: Developing device 24: Developing roll 28: Developing bias power supply for copying

Claims (3)

[Claims] (1) An exposure device for copying that irradiates the surface of a charged photoconductor with a light image corresponding to the image of a document, and a light image scanning device for a printer that irradiates the surface of a photoconductor that is charged according to an image signal. a developing device that uses a one-component magnetic toner for visualizing an electrostatic latent image formed on the surface of a photoreceptor;
In an electrophotographic copying printer device, which is equipped with a power supply device that applies developing biases of different potentials in copy mode and print mode, and performs forward development in copy mode and reverse development in print mode, one-component magnetic toner is An electrophotographic copy printer device characterized in that the overall charge polarity is biased to the side that matches the polarity of toner adhering to the surface of a photoreceptor during a print mode. (2) The electrophotographic copy printer apparatus according to claim 1, wherein the overall charging polarity of the one-component magnetic toner matches the charging polarity of the binder resin itself of the toner. (3) The overall charging polarity of the one-component magnetic toner matches the charging polarity of the entire binder resin including additives added to the binder resin of the toner. electrophotographic printer equipment.