JP2774273B2 - Image forming method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming method in which an exposing unit and a developing unit are installed to face each other with a photoconductor interposed therebetween, and a toner image is formed simultaneously with image exposure. A pulse voltage applying means for applying a pulse voltage to the sleeve to be applied is provided, and a pulse voltage is applied to the sleeve at the time of image exposure to form an image and perform contrast development during another period. Image formation. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method in which a toner image is formed on a photoconductor at the same time as image exposure, and display or transfer is performed. Development, optical printers, and copiers generally perform recording using electrophotography, and perform recording by processes such as charging, exposure, development, and transfer. In the charging step, a corotron which performs charging by corona discharge is used, which requires a high voltage and has a problem that harmful ozone is generated. Therefore, an image forming method that does not generate harmful ozone and can form an image at a low voltage is desired. FIG. 4 is a view for explaining an image forming method that does not generate such ozone and does not use a corona charger capable of forming an image at a low voltage. In this image forming method, as shown in FIG. 4, a transparent conductive layer 112 made of ITO or the like is provided on a transparent substrate 111, and a photosensitive member 113 made of CdS or the like having a thickness of, for example, 65 μm is provided thereon. Further, a conductive magnetic toner developing device 116 is disposed opposite to a recording film 115 provided with a white insulating layer 114 having a certain resistance value, and a voltage is applied between the developing device 116 and the transparent conductive layer 112. While, the light source 117 composed of a semiconductor laser or the like,
Image exposure is performed from the transparent substrate 111 side by a polygon scanner 118, an fθ lens 119, and the like. By this image exposure, the developing machine 116 and the recording medium film 1
After a voltage is applied between the transparent conductive layer 112 and the fifteen transparent conductive layers 112, the toner is electrostatically attached to a portion of the photosensitive layer 113 whose resistance value has been reduced by light irradiation. On the other hand, since the thickness of the insulating layer 114 is sufficiently large in the part where the light is not irradiated, the electrostatic adhesion between the insulating layer 114 and the toner is weak, and the toner is not deposited on the recording film 115. Will not adhere. Therefore, a toner image 120 corresponding to the image exposure is formed. After image formation, the charge induced by light irradiation and the charge induced by the toner are discharged through the surface layer in one cycle of image display, and are magnetically attracted and collected by the developing device 116 at the next image formation. Is done. In this case, since the image exposure is performed from the transparent substrate 111 side of the recording film 115,
The toner collection, image exposure, and development can be performed simultaneously. Such an image forming method is known in JP-A-57-119375. However, the conventional image forming apparatus as shown in FIG. 4 has an advantage of not using a corona discharger, but forms an image by utilizing a difference in cloning force acting on toner between an exposed portion and a non-exposed portion. The photoreceptor layer 113
Must be thicker. However, the thick photoreceptor layer 113
Is difficult to form to a uniform thickness. In addition, there is a disadvantage that the use of a large amount of material increases the cost by increasing the thickness of the photoconductor layer. Further, as the thickness of the photoconductor layer 113 increases, the voltage applied between the transparent conductive film 112 of the recording film 115 and the developing device 116 needs to be increased, and the photosensitivity decreases. [Prior art] Therefore, a new image forming method capable of forming an image on a low-voltage, high-sensitivity and thin photoreceptor without using a corona discharger by improving all of the above-mentioned conventional drawbacks has been developed. Has been proposed. As the image forming method, two kinds of methods as shown in FIGS. 5 and 6 can be considered depending on the mobility of the photoconductor used. FIG. 5 shows a photoreceptor having a low mobility, for example,
It is a method that can be applied to non-polluting and inexpensive organic photoreceptors. FIG. 6 shows a method for relatively high-mobility photoreceptors, for example, high-speed type organic photoreceptors, Se photoreceptors, and CdS photoreceptors. It is a method that can be applied. First, an outline of the proposed principle of FIG. 5 will be described. The photoconductor 124 includes a transparent substrate 121, a transparent conductive film 122, and a photoconductive layer 1.
23 are sequentially laminated, and the transparent conductive layer 123 is connected to the ground. Reference numeral 125 denotes first developing (solid toner developing) means, specifically, a configuration in which a non-magnetic sleeve is provided on the surface of a magnet roller, and a carrier made of conductive magnetic toner or conductive iron powder And a so-called magnetic brush developing machine. A developing bias voltage is applied between the sleeve of the developing machine and the transparent conductive film by the power supply 126. Reference numeral 127 denotes a uniform solid toner layer formed in a photoconductor shape. 128 is an image exposure means, specifically, a cell hook lens and an LED.
It is an LED array optical system composed of an array. Reference numeral 129 denotes a photocarrier near the surface of the photoreceptor layer, which becomes a latent image charge. Reference numeral 130 denotes a toner in an exposed portion. 131 is a second developing (contrast developing) means for collecting the toner in the non-exposed area,
Specifically, it is a magnetic brush developing machine similar to that used for forming a uniform solid toner layer. A voltage having a polarity opposite to the developing bias voltage of the first developing device is applied to the second developing device by a power supply 132. Reference numeral 133 denotes a toner image from which the non-exposed portion toner has been removed. Next, an image forming procedure will be described. In FIG. 5, a uniform bias toner layer is formed on the surface of the photoconductor by applying a developing bias to the developing device 125 and conveying the toner. Image exposure is performed by the image exposure device 128 from the transparent substrate side of the photoconductor 124. In the exposed portion, the carrier of the photocarrier generated in the photoconductive layer and having the polarity opposite to that of the solid toner layer 127 moves toward the surface and becomes a latent image charge. Next, the toner is conveyed by the developing device 131 connected to the reverse bias voltage, and the toner 134 in the non-exposed portion is
Is collected in the developing device 131 by electrostatic force. At this time, the toner 130 in the image portion is also slightly recovered, but most of the toner remains on the photoconductor due to the electrostatic binding force between the latent image charge 129 and the toner charge, and a toner image is formed. If necessary, the toner image is transferred to a normal transfer unit 135.
After the transfer to the recording paper 136, the latent image charge on the photoreceptor is removed by a light neutralizer 137 or the like, and collected by the first developing device. The next image formation is performed simultaneously with the collection of the residual toner. By repeating the above process, continuous recording is performed. Next, the outline of the second proposed principle shown in FIG. 6 will be described. FIG. 6 differs from FIG. 5 in that an image exposure and development process for simultaneously performing solid toner development and image exposure is employed. For this reason, in the exposed area during image exposure and development, the photoconductor capacity apparently increases, so that the amount of toner adhered to the exposed area increases, and a toner image with a certain level of contrast is obtained between the exposed area and the non-exposed area. Can be It can be seen that the method shown in FIG. 6 is advantageous for the photoconductor having such a high moving speed. [Problems to be Solved by the Invention] However, in the image forming method as shown in FIGS. 5 and 6, it is necessary to perform two types of development, that is, solid toner development and contrast development. Has the disadvantage that it becomes complicated. Therefore, in the present invention, even if the image forming method adopts the above-described process and does not use the corona discharger, it is possible to perform one development without performing two developments of solid toner development and contrast development at the time of image formation. An object of the present invention is to provide an image forming method capable of performing development without fogging on a developing machine, thereby simplifying the configuration of the developing machine. [Means for Solving the Problems] FIG. 1 is a diagram for explaining the principle of the image forming method according to the present invention. In the figure, reference numeral 1 denotes a photoconductor, which is formed by sequentially laminating a transparent substrate 1a, a transparent or translucent conductive layer 1b connected to the ground, and a photoconductive layer 1c. A toner 6 having a magnetic sleeve 2a and a magnet roller 2b, which is positively or negatively charged (negative in FIG. 1) toward the photoreceptor 1;
5 is an image exposure means, and is a transparent substrate 1a
A device that irradiates light corresponding to recorded information onto the photoreceptor 1 from the side to perform image exposure. Reference numeral 7 denotes pulse voltage applying means.
A first voltage value, which is a negative voltage value for moving the negatively charged toner 6 from the developing device 2 side to the photoreceptor 1 and attaching it to the photoreceptor 1
And a second voltage value 7a which is a positive voltage value for recovering the toner 6 adhering on the photoreceptor 1 to the developing device 2 side.
Is applied to the sleeve 2a with a pulse voltage (referred to as a recording pulse) set to the voltage value 7b. The pulse voltage applying means 7 is configured to apply the first voltage value 7a to the sleeve 2a at the time of image exposure by the image exposing means 5, and to always apply the second voltage value 7b to the sleeve 2a. ing. [Operation] In the above-described configuration, image formation is performed as follows. First, at the time of non-toner image formation, the second
Is applied to prevent the toner 6 from adhering to the non-toner image forming portion. Then, at the time of forming a toner image, the toner 6 is caused to adhere to the photoreceptor 1 by applying the first voltage value 7a to the sleeve 2a simultaneously with the image exposure by the image exposure means 5. That is, by applying the first voltage value 7a, the photosensitive member 1
The toner adheres to both the exposed portion and the non-exposed portion. But,
In the exposure section, photocarriers are generated in the photoconductive layer 1c by image exposure, and of the photocarriers, carriers (+) having a polarity opposite to the first voltage value 7a move to the vicinity of the surface of the photoconductive layer 1c. Since the latent image charge 8 is used, the latent image charge 8 apparently increases the capacity of the photoconductor, so that the amount of adhered toner increases. Next, the recording pulse is turned off, that is, to the second voltage value 7b, and the sleeve 2a is kept at a potential opposite to that of the recording pulse. Then, by applying the first voltage value 7a to the sleeve 2a, the toner adhering to the exposed portion and the non-exposed portion on the photoreceptor 1 is collected by the developing device 2. However, at this time, most of the toner remains on the photoreceptor 1 in the exposed portion due to the electrostatic restraining force of the latent image charges 8 and the toner charges formed in the photoconductive layer 1c. Along with the movement of the photoconductor 1, a recording pulse is applied at the same time as image exposure for the next new recording, and the adhesion and collection of the toner on the photoconductor 1 are repeatedly performed as described above. . As described above, by applying the recording pulse, the toner is attached and collected at the same time as the image exposure, and the toner attached to the non-exposed portion, which is the background portion, can be collected.
When the photoconductor 1 leaves the development area, a toner image 3 without fog is obtained. Embodiment FIG. 2 is a schematic configuration diagram when the image forming method according to the present invention is applied to an image recording apparatus. In the figure, reference numeral 21 denotes a photosensitive drum on which a transparent conductive film (21b) is vacuum-deposited on a transparent glass drum 21a, and a Se-based photosensitive member is further deposited. A magnetic brush developing machine 22 and a transfer roller 30 composed of a conductive rubber roller are arranged around the photosensitive drum 21. The magnetic brush developing machine 22 applies a recording pulse 27 to the transfer roller 30 and applies a transfer voltage (+ 500V) 31 to the transfer roller 30. Are respectively applied. The magnetic brush developing device 22 includes a non-magnetic sleeve 22a and a magnet roller 22b, and conveys the conductive magnetic toner 26 in a direction opposite to the traveling direction of the photosensitive drum 21 by the relative rotation of both. On the other hand, an LED exposure system 25 including a 240 dpi LED array 25a and a selfoc lens 25b is provided inside the photosensitive drum 21 at a position facing the magnetic brush developing machine 22.
Further, an LED array bar 24 is provided as a charge elimination light source. Next, a recording procedure of the image recording apparatus shown in FIG. 2 will be described. First, the photosensitive drum 21 is rotated at a peripheral speed of 50 mm / s, for example, in the direction of the arrow in the figure. The image exposure is performed by the LED optical system 25 while the toner is transported by the magnetic brush developing machine 22. At this time, a recording pulse is applied to the sleeve 25a in synchronization with the image exposure. The recording pulse applied at this time is shown in FIG. The recording voltage value is -250 V and the OFF state is 30 V. Recording cycle is 240dpi
(9.4 dots / mm), the recording speed is determined to be 2.1 ms from a peripheral speed of 50 mm / s. The recording pulse width was 0.1 ms. As a result, the duty ratio of the recording pulse becomes 4.8%. Photocarriers are generated in the image area by the image exposure and the application of the recording pulse, and move to the surface of the photoreceptor to form a latent image charge 28. Further, while the image exposure is being performed, the application of the recording pulse is completed,
The potential of the sleeve is fixed at 30V. As a result, the toner in the background portion is electrostatically collected and an image is formed. As described above, the duty ratio of the recording pulse is 4.8%, which can be converted into the amount of movement of the photosensitive drum.
It is 5 μm for 106 μm. This value is sufficiently small that the toner hardly adheres. The toner image 23 formed as described above is transferred onto the recording paper 29 by the transfer roller 30, and becomes a toner image 32 on the recording paper. Thereafter, the image is fixed to the recording paper 29 by a fixing device (not shown), and permanent image recording is performed. Residual toner 33 remaining on photoreceptor drum 21 without being transferred
Is discharged by the LED array bar 24 and the electrostatic coupling force is weakened. The toner 34 thus neutralized is collected by the magnetic brush developing machine 22 and used again for recording. The above procedure is repeated, and continuous recording is performed. According to this embodiment, there is an effect that recording can be performed at a low voltage by using a simple developing device having a single-stage roller configuration. As another embodiment of the present invention, a case using a two-component developer composed of a carrier and a toner will be described. The configuration of the applied image recording apparatus is the same as that of the embodiment shown in FIG. In this embodiment, the carrier is a resin carrier in which about 80% of magnetic powder is mixed in the resin. The particle size is 15μm,
The resistivity is 10 ⁵ Ωcm. In addition, iron powder, ferrite carrier and the like can be used as the carrier. As the toner, an insulating toner having a particle size of 10 to 15 μm was used. Recording is possible at a developer toner concentration of 20 to 40% by weight. In the present embodiment, the value of the recording pulse is suitably from -500 to -600 V, and from 30 to 60 V in the OFF state. According to this embodiment, in the above-described embodiment, the transfer characteristics at high humidity may be deteriorated, but there is an advantage that stable transfer characteristics can be obtained by using the insulating toner. As still another embodiment, the residual toner on the photoreceptor is
A configuration in which a cleaner such as a brush or a blade is provided and removed may be employed. Further, the present invention can be applied to a display in which a toner image on a photoconductor is directly viewed without performing transfer to a recording sheet. In these embodiments, the shape of the photoconductor is not limited to a drum, and a photoconductor layer may be formed on an endless film. Alternatively, a photoconductor in which an insulating layer is provided on a photoconductive layer can be used. In this case, since the photoconductive layer is protected by the insulating layer, there is an advantage that the life of the photoconductor can be extended. Further, there is an advantage that the latent image charge and the toner form a complete electric double layer by the insulating layer, and a more uniform toner image can be obtained as compared with the case where only the photoconductive layer is used. Further, the photoconductive layer material is not limited to the selenium-based photoconductor, but
-A photosensitive member having high mobility such as SiCdS can be used. In addition, laser, liquid crystal shutter, E
It is also possible to use an optical system using L or the like. [Effect of the Invention] According to the present invention, the sleeve of the developing machine at the time of image exposure,
By applying a pulse-like recording voltage and maintaining a potential (contrast development potential) of the opposite polarity to the recording voltage at other times, it becomes possible to perform image formation and contrast development with a single-stage developing machine, thus simplifying the process. A low-voltage image forming method can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram for explaining the principle of the present invention, FIG. 2 is a block diagram showing one embodiment of the present invention, FIG. 3 is a diagram showing a recording pulse waveform in the embodiment, FIG. 4 is an explanatory view of a conventional example, FIG. 5 is a view for explaining a first conventional example, and FIG. 6 is a view for explaining a second conventional example. In the figure, 1 is a photoconductor, 1a is a transparent substrate, 1b is a transparent or translucent conductive layer, 1c is a photoconductive layer, 2 is a developing machine, 2a is a sleeve, 2b is a magnet roller, 3 is a toner image, 5 is Image exposure means, 6 is toner, 7 is pulse voltage applying means, and 8 is latent image charge.

   ────────────────────────────────────────────────── ─── Continuation of front page       (56) References JP-A-60-101570 (JP, A)                 JP-A-57-202568 (JP, A)                 JP-A-50-30537 (JP, A)                 JP-A-60-22146 (JP, A)

Claims (1)

(57) [Claims] A rotatable photoconductor (1) in which at least a transparent or translucent conductive layer (1b) and a photoconductive layer (1c) are sequentially laminated on a cylindrical transparent substrate (1a); and a conductive non-magnetic sleeve ( 2a) and Mcnet Laura (2b)
A developing device (2) disposed outside the photoconductor (1), for supplying a positively or negatively charged toner (6) onto the photoconductive layer (1c); The photoconductor (1) is disposed inside the photoconductor (1) so as to face the developing device (2) via the transparent substrate (1a), the conductive layer (1b), and the photoconductive layer (1c). Image exposure means (5)
A first voltage value (7a) for moving the toner (6) from the developing device (2) side to the photoconductor (1) and attaching the toner (6) to the photoconductive layer (1c); A second voltage value (7) having a polarity opposite to the first voltage value (7a) for collecting the toner (6) adhered on the layer (1c) to the developing machine (2) side.
b) the pulse voltage set in the sleeve (2a)
And a pulse-shaped voltage applying means (7) for applying a voltage to the photoconductive layer (1c) of the photoconductor (1) in a rotating state. The pulse-like voltage applying means (7) sets the sleeve (2a) to the first voltage value (7a) to deposit the toner (6) on the photoconductive layer (1c); Before the end of the image exposure, the pulse voltage applying means (7) changes the voltage value of the sleeve (2a) to the first voltage value (7a).
To the second voltage value (7b) to collect the toner adhered to at least the non-exposed portion of the photoconductive layer other than the exposed portion of the toner (6) adhered at the time of setting the first voltage. And this step is repeated for each image exposure to form a toner image (3) on the photoconductive layer (1c).
Forming an image. 2. The image forming method according to claim 1, wherein the pulse voltage applying unit applies the first voltage value for a time shorter than the image exposure time.