JPH04263269A - Image forming device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus that forms an image by electrostatically adhering a conductive magnetic developer to a recording medium.

0002

[Prior Art] Various devices that form images according to image information have been developed and put into practical use, and some of them use conductive magnetic toner, which is a fine powder developer, to electrostatically charge the toner. There are image forming devices such as printers and display devices that form images by attaching them to recording media.

As an image forming method applied to the above-mentioned apparatus, a method disclosed in, for example, Japanese Patent Publication No. 51-46707 has been proposed. As shown in FIG. 9, the non-magnetic cylinder 5
A rotating magnet 52 that is provided concentrically with the non-magnetic cylinder 50 and rotates at a constant speed holds the conductive magnetic toner 51 on the outer periphery of the cylinder 50.
It is attached to the outer circumferential surface of the cylinder 50 and conveyed by the alternating magnetic field formed by the cylinder 50. Then, the toner 51 is passed through recording electrodes 53 densely arranged along the axial direction on the outer peripheral surface of the non-magnetic cylinder 50, and the conductive layer 54b, A voltage is applied by the recording control unit 55 while physically contacting the recording medium 54 formed by laminating the insulating layer (or dielectric layer) 54a. At this time, by applying a voltage according to the image information between the recording electrode 53 and the conductive layer 54b of the recording medium 54, the toner 51 is attached to the insulating layer 54a of the recording medium 54 to form an image. be.

Further, as an image forming apparatus to which the above image forming method is applied, as shown in FIG.
6a and the driven conveyance roller 56b, the recording electrode 53 is rotated by the rotation of the rotating magnet 52.
The toner 51 is conveyed thereon, and an image is formed by attaching or not attaching the toner 51 according to a signal voltage from a recording control section 55 shown in FIG. For example, when the signal voltage from the recording control section 55 is +30V, the toner 51
Image formation is performed by repeating an operation in which the voltage adheres to the recording medium 53 and does not adhere when the voltage is 0V. An image is displayed on the toner 51 adhering to the recording medium 53 when it passes through the cover glass 57, and then the cleaning member 58 scrapes off the toner 51 from the recording medium 53 and drops it onto the non-magnetic cylinder 50, and conveys it again. and prepare for the next record.

FIG. 9 shows a driver circuit for one pixel of the recording control section 55. For example, when displaying a black image on the recording medium 54, the image signal is set to High, and a recording voltage is applied to the recording electrode 53 by turning on the transistor Tr1 and turning off the transistor Tr2 by the transistor drive circuit 59. do. Furthermore, when displaying a white image on the recording medium 54, the image signal is
OW, and the transistor drive circuit 59 turns off the transistor Tr1 and turns off the transistor Tr2.
By applying N, a recording voltage is applied to the recording electrode 53. In this way, by setting the potential of the recording electrode 53 to 0V, the voltage at which the toner 51 stands up is set to 0V, and adjustment is made so that the toner 51 does not adhere to the non-image forming area of the recording medium 54.

[0006]

However, in the above-mentioned prior art, when displaying a white image, the potential of the recording electrode 53 is set to 0 V to prevent the toner 51 from adhering to the recording medium 53, and the recording medium 54 itself is White was expressed through color. Therefore, when charges are accumulated on the recording medium 54 due to factors such as frictional charging, even if the potential of the toner 51 is 0V, the toner 51 is attracted to the charges on the recording medium 54 and is transferred to the recording medium 54. There was a risk that the white image would become dirty. Generally, when the humidity in the air decreases, the surface resistance of a substance increases, making it more likely to be triboelectrically charged. Therefore, especially during periods when the air is dry, such as in winter, the toner 51 tends to adhere to the recording medium 54 due to static electricity, often resulting in distorted images.

An object of the present invention is to provide an image forming apparatus that can display a clear white image by neutralizing the electrical charges generated on the recording medium depending on the environmental conditions around the recording electrode. be.

[0008]

[Means for Solving the Problems] A typical means for solving the problems of the prior art described above and applied to the embodiments described below is to apply a signal voltage according to image information to relatively move the developer. a recording electrode that is attached to a recording medium that is moved to form an image, a developer supplying means for supplying developer between the recording electrode and the recording medium, and an environmental condition around the recording electrode that is detected. and a control means for controlling a signal voltage applied to the recording electrode to a predetermined value in accordance with a detection signal of the detection means, and the control means has a detection means for controlling a signal voltage applied to the recording electrode to a predetermined value in accordance with a detection signal of the detection means, and the control means has a detection means for controlling the signal voltage applied to the recording electrode to a predetermined value in accordance with the detection signal of the detection means, It is characterized in that a polar signal voltage is applied to the recording electrode.

[0009]

[Operation] According to the above structure, the control means for controlling the signal voltage applied to the recording electrode to a predetermined value is used to remove, for example, residual charges remaining on the recording medium due to previous recording and developer attached to the recording medium. By applying a signal voltage of opposite polarity to the charged charge generated by rubbing etc. during the recording to the recording electrode according to the surrounding environmental conditions detected by the detection means,
Charges generated on the recording medium can be effectively neutralized.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image forming apparatus to which the present invention is applied will be described below with reference to the drawings. In this embodiment, a display device will be described as an image forming device.

FIG. 1 is a schematic cross-sectional view of an image recording section including a control block for applying a recording voltage to a recording electrode, FIG. 2 is a cross-sectional explanatory diagram showing a schematic configuration of an image forming apparatus, and FIG. 3 is a perspective explanatory diagram of a recording electrode. , FIG. 4 is a partially enlarged sectional view of the recording medium, FIG. 5 is a block diagram of applied voltage generation when displaying a white image, and FIG. 6 is a graph showing the relationship between the white image applied voltage and humidity.

First, the general structure of the display device will be explained with reference to FIGS. 2 to 4. In FIG. 2, reference numeral 1 denotes a recording electrode for applying a recording voltage to a conductive magnetic developer (hereinafter referred to as "toner") 2 in accordance with image information. This recording electrode 1 includes a non-magnetic cylinder (hereinafter referred to as "sleeve") 3 which is a developer supply means for supplying toner 2.
is attached along the axial direction on the outer peripheral surface of the

As shown in FIG. 3, the recording electrode 1 has an electrode pattern formed of a plurality of signal lines on a flexible printed circuit board 1a, and each signal line is a recording electrode for applying a recording voltage according to image information. It is connected to the driver 1b. A conductor exposed portion 1c contributing to recording is provided at the tip of the signal line, and each conductor exposed portion 1c is formed corresponding to one pixel in the main scanning direction. The recording electrode 1 other than the exposed conductor portion 1c is covered with an insulating cover film 1e. Further, a plurality of holes 1d are bored in the flexible printed circuit board 1a along the axial direction of the sleeve 3. These holes 1d are
The toner 2 conveyed on the outer periphery of the sleeve 3 passes in the direction of arrow a and reaches the exposed conductor portion 1c. In this embodiment, the recording electrode driver 1b is a VFD driver (Oki Electric MSG11).
63) is used, and the signal line is formed with a copper etching pattern.

As shown in FIG. 2, inside the sleeve 3, a rotating magnet 4 which is rotationally driven by a drive source (not shown) is mounted concentrically around a rotating shaft 4a. As the rotating magnet 4, a cylindrical magnetic roller having 10 to 20 magnetic poles was used, and the maximum magnetic flux density directly above the magnet was about 100 to 200 Gauss. The toner 2 is attached to the outer circumferential surface of the sleeve 3 and conveyed by an alternating magnetic field formed by the rotating magnet 4.

In the vicinity of the recording electrode 1, an endless belt-shaped recording sheet 5, which is a recording medium on which toner 2 is attached to form an image, is arranged with a portion of the recording sheet 5 close to it. The recording sheet 5 is stretched between a driving roller 6a and an auxiliary conveying roller 6b which are arranged in a pair above and below. The drive roller 6a is rotationally driven by a drive motor (not shown) and conveys the recording sheet 5 in the direction of arrow b in FIG.

The recording sheet 5 has, as shown in FIG.
A surface layer 5a made of a transparent material whose main component is a plastic resin such as butyral resin, acrylic resin, nylon resin, or polyester resin; a white layer 5b made of a white inorganic substance and a binder (acrylic resin, plastic resin);
It is constructed by polymerizing a conductive layer 5c on which aluminum or ITO (indium and tin oxide) is vapor-deposited to provide conductivity, and a base material 5d made of a plastic resin such as polyethylene terephthalate, polyethylene, or polypropylene. . Further, a portion of the conductive layer 5c is provided with a conductive portion 5e made of carbon paste and connected to the ground via a resistor. Further, the surface layer 5a and the white layer 5b are electrically insulated, and the white layer 5b contains titanium oxide (TiO2) and aluminum oxide (AlO3) to produce white as the base color of the screen.
) and other inorganic substances are used. The structure of the recording sheet 5 is shown in the table below. (Margin below)

A signal voltage corresponding to image information is applied between the exposed conductor portion 1c of the recording electrode 1 and the conductive layer 5c of the recording sheet 5 using a circuit configuration described later, so that the surface layer 5a of the recording sheet 5 is heated. An image is formed by electrostatically depositing toner 2 thereon.

The toner 2 has a volume resistivity of 103 to 109 Ωcm and an average volume particle diameter of 10 to 12 μm.
m, composition is plastic resin such as acrylic resin, nylon resin, polyethylene, polypropylene, carbon 1-10% (weight ratio), ferrite 40-70%
(weight ratio) was used.

A humidity sensor 7 is a detection means for detecting the temperature and humidity around the recording electrode 1. 8 again
is the recording electrode 1 according to the detection result of the humidity sensor 7.
This is a recording control unit which is a control means for controlling the signal voltage applied to an arbitrary value.

9 is the toner 2 attached to the recording sheet 5.
This is a cleaning brush that serves as a developer removal means to remove developer by rubbing. As the cleaning brush 9, a brush made of carbon fiber having a volume resistivity of 100 to 103 Ωcm was used. The above cleaning brush 9
By rubbing the recording sheet 5 at an appropriate angle and distance, the toner 2 adhering to the recording sheet 5 is scraped onto the sleeve 3.

Reference numeral 10 is a support member for supporting the recording sheet 5 without sagging, and reference numeral 11 is a magnet for collecting and scraping off the toner 2 after image formation.

The toner 2 adhered to the outer periphery of the sleeve 3 by the rotating magnet 4 and conveyed passes through the hole 1d of the substrate 1a and is conveyed onto the exposed conductor portion 1c of the recording electrode 1. The rotating magnet 4 rotates at a rotational speed such that at least one magnetic pole passes directly under the conductor exposed portion 1c for recording at least one main scanning line. Therefore, by applying a recording voltage to the recording electrode 1 according to the image information, the toner 2 can be attached to the recording sheet 5 to form an image. Note that the toner 2 that did not contribute to image formation on the recording electrode 1 falls from the circumferential surface of the sleeve 3, and
The image formed on the recording sheet 5 is not affected. The image formed on the recording sheet 5 is rotated by the rotation of the drive roller 6a so that the recording sheet 5 is rotated by the arrow b in FIG.
direction, and when it passes through the image display section 12, it is displayed externally. Then, the toner 2 adhering to the recording sheet 5 that has passed through the image display section 12 is stripped off by the cleaning brush 9, and the toner 2 falls onto the sleeve 3 and is conveyed again for the next recording. Be prepared.

Next, the driving operation of the recording control section 8 will be explained with reference to the recording voltage generating circuit shown in FIG. A recording voltage VBLACK for displaying a black screen is constantly applied to the recording electrode 1 via the transistor Tr1. Further, 8a is a transistor drive circuit that selectively operates the transistor Tr1 or the transistor Tr2 according to the image signal. Further, the humidity sensor 7 is provided with a bias circuit for applying a recording voltage VWHITE for displaying a white image based on detected humidity data (a function using humidity as a variable), and an AD converter 8b, data ROM8c for conversion, DA converter 8d
, a signal amplifier 8e are connected in sequence, and the recording voltage VWHITE adjusted to a predetermined value is applied to the transistor Tr.
2 to the recording electrode 1.

In the above configuration, when an image signal is input to the transistor drive circuit 8a, if the image signal indicates a black screen display, the transistor Tr1 is turned on and the transistor Tr2 is turned off. At this time, a recording voltage VBLACK is applied to the recording electrode 1, and the toner 2 adheres to the recording sheet 5. Similarly, when the image signal is a white image display, the transistor Tr1 is turned off, the transistor Tr2 is turned on, and the recording voltage VWHITE adjusted according to the humidity data is applied. This recording voltage VWH
The ITE measures the relationship between the charge on the recording sheet 5 and the humidity around the recording electrode 1 in advance, and applies a voltage of opposite polarity through the recording electrode 1 to cancel the charged charge when displaying a white image. It is applied. The relationship between the humidity around the recording electrode 1 and the recording voltage when displaying a white image is shown in the graph of FIG.

The procedure for generating the recording voltage VWHITE when displaying a white image based on the humidity data from the humidity sensor 7 in the recording control section 8 will now be described with reference to FIG. FIG. 5 shows a block diagram of the recording voltage VWHITE generation circuit and a graph of input/output characteristics. In FIG. 5, the relationship between humidity and the output voltage of the humidity sensor 7 is in direct proportion as shown in the graph, and the maximum output voltage VMAX is output at 100% humidity. The output voltage from the humidity sensor 7 is input to the AD converter 8b, which converts the input voltage into an 8-bit digital signal in the range of 0V to VMAX. The output voltage data converted to 8 bits is input to the data conversion ROM8c, and the data conversion ROM
8c outputs 8-bit output voltage data corresponding to digital humidity data according to the graph shown in FIG. (For example, when the humidity is 49%, an output voltage of -2V is applied.)
The t output voltage data is input to the DA converter 8d. The DA converter 8d converts the output voltage data of the data conversion ROM 8c into an analog quantity, and converts the input 8-bit data FFH to VWHITE (-5V in this embodiment) and 00H to 0V, respectively, to the signal amplifier. 8e. The signal amplifier 8e is D
A recording voltage VWHITE is applied to the recording electrode 1 through the transistor Tr2 by amplifying the signal voltage input from the A converter 8d and adjusting the polarity to be opposite to the charge charged in accordance with the humidity.
Apply. By applying an appropriate white image display voltage according to the environmental humidity as described above, the recording sheet 5
The toner 2 can be prevented from adhering to the recording sheet 5 under any environmental conditions, and a clear white image can be displayed.

Next, another embodiment of the recording voltage VWHITE generation circuit for displaying the above-mentioned white image will be described. In the above example, the value of the recording voltage VWHITE was adjusted and applied according to the change in the humidity around the recording electrode 1, but in this example, in addition to this, the value of the recording voltage VWHITE was adjusted according to the charging characteristics of the recording sheet 5 due to a change in temperature. The recording voltage VWHITE is set to MP as described below.
It is calculated by U (microprocessor) and applied to the recording electrode driver 1c.

The graph of FIG. 7 shows the relationship between the correction coefficient ξ of the recording voltage VWHITE for displaying a white image and the temperature change in this embodiment. Even if the humidity is constant, if the temperature changes, the characteristics of the recording sheet 5 and the toner 2 will change, and the amount of residual charge on the recording sheet 5 will change, so the recording voltage VWHITE cannot be specified by humidity alone. Therefore, in this embodiment, a correction coefficient based on temperature changes is prepared in the MPU, and the recording voltage VWHITE is determined by multiplying the recording voltage determined from the humidity shown in the graph of FIG. 6 by the correction coefficient according to the temperature. It is something. The configuration of the recording control section 13 will be described below with reference to FIG. 9.

A recording voltage VBLACK for displaying a black screen is constantly applied to the recording electrode 1 via the transistor Tr1. Further, 13a is a transistor drive circuit that selectively operates the transistor Tr1 or the transistor Tr2 according to the image signal. Further, a humidity sensor 14 and a temperature sensor 15 are provided near the recording electrode 1 to detect the humidity and temperature around the recording electrode 1. The humidity sensor 14 and temperature sensor 15
A bias circuit is provided for applying a recording voltage VWHITE for displaying a white image based on detected humidity and temperature data.

AD converters 13b1 and 13b2 are connected to the humidity sensor 14 and temperature sensor 15, and convert the output voltages of the humidity sensor 14 and temperature sensor 15 into digital signals. Said AD converter 1
The output signals of 3b1 and 13b2 are input to the MPU 13c, and are multiplied by digital data to calculate an appropriate recording voltage VWHITE. In this embodiment, the recording sheet 5 having the configuration shown in FIG. Voltage correction is required. For example, humidity 20%, temperature 3
In the case of 5° C., it becomes 4.5×0.75=3.38V. (The recording voltage at 20% humidity is 4.5 V, and the temperature is 3.
The correction coefficient ξ at 5°C is 0.75) The above MPU13c
The recording voltage calculated is converted into an analog quantity by a DA converter 13d, then amplified by a signal amplifier 13e, and applied to the recording electrode 1 via the transistor Tr2. According to the above configuration, a clear white image can be obtained by applying an appropriate recording voltage even when not only the humidity but also the temperature changes.

[0030]

Effects of the Invention As described above, the present invention uses a control means to control the signal voltage applied to the recording electrode to a predetermined value.
For example, the ambient environmental conditions detected by the detection means are signal voltages of opposite polarity to the charged charges caused by residual charges remaining on the recording medium due to previous recording or rubbing when removing developer attached to the recording medium. By applying the voltage to the recording electrodes in accordance with the above, it is possible to effectively neutralize the electrical charges generated on the recording medium. Thereby, when displaying a white image, it is possible to prevent developer from adhering to the recording medium and obtain a clear image.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an image recording section including a recording voltage generation circuit.

FIG. 2 is a cross-sectional explanatory diagram showing a schematic configuration of an image forming apparatus.

FIG. 3 is a perspective explanatory diagram of a recording electrode.

FIG. 4 is a partially enlarged sectional view of a recording medium.

FIG. 5 is a block diagram of applied voltage generation when displaying a white image.

FIG. 6 is a graph showing the relationship between white image applied voltage and humidity.

FIG. 7 is an explanatory diagram of another example of a recording voltage generation circuit.

FIG. 8 is a graph showing the relationship between temperature and correction coefficient.

FIG. 9 is an explanatory diagram showing the conventional image recording principle.

FIG. 10 is a cross-sectional explanatory diagram of a conventional image forming apparatus.

[Explanation of symbols]

1 is a recording electrode, 1a is a substrate, 1b is a recording electrode driver,
1c conductor exposed part, 1d hole, 1e cover film, 2
3 is a toner, 3 is a sleeve, 4 is a rotating magnet, 5 is a recording sheet, 6a is a drive roller, 6b is an auxiliary conveyance roller, 7, 1
4 is a humidity sensor, 8, 13 is a recording control unit, 8a, 13a
are transistor drive circuits, 8b, 13b1, 13b2
is AD converter, 8c is bias generation ROM, 8d
, 13d are DA converters, 8e and 13e are signal amplifiers, 9 is a cleaning brush, 10 is a support member, 11 is a magnet, 12 is an image display section, 13c is an MPU, and 15 is a temperature sensor.

Claims (5)

[Claims] 1. A recording electrode that forms an image by applying a signal voltage according to image information to cause a developer to adhere to a relatively moving recording medium, and a developing device between the recording electrode and the recording medium. a developer supplying means for supplying developer; a detection means for detecting environmental conditions around the recording electrode; and control for controlling a signal voltage applied to the recording electrode to a predetermined value in accordance with a detection signal of the detection means. An image forming apparatus comprising: means for controlling an image forming apparatus, wherein the control means applies a signal voltage having a polarity opposite to the electric charge generated on the recording medium to the recording electrode. 2. The image forming apparatus according to claim 1, wherein the control means adjusts and applies the recording voltage according to a function that uses a change in humidity around the recording electrode as a variable. 3. The image forming apparatus according to claim 1, wherein the control means corrects and applies the recording voltage using a function that uses a temperature change around the recording electrode as a variable. 4. The image forming apparatus according to claim 1, wherein the recording medium has a surface transparent resin layer, a colored inorganic substance, and a conductive layer in this order. 5. A display device in which the image formed on the recording medium is displayed on a display unit.
The image forming apparatus described above.