JPH047585A - Image forming device - Google Patents

Abstract

PURPOSE:To eliminate the fogging of a recording medium and to expand the use environment range by varying a bias voltage applied to a cleaning member according to a change in the environmental condition of humidity at least. CONSTITUTION:This device is equipped with a recording electrode 1, the recording medium, a developer recording means 3, the cleaning member 9, a detecting means 13 for detecting the temperature in the device, and a bias means 16 which varies the bias voltage applied to the cleaning member 9 according to the temperature detected by the detecting means 13. Then when the temperature in the device is high, the bias means 16 makes the variation width of the bias voltage applied to the cleaning member 9 less than that on a low-temperature side. Therefore, even if the environmental condition changes, the application of the bias voltage to the cleaning member 9 is eliminated. Consequently, fogging with a developer is prevented to maintain image quality and the use environment range of the device can be expanded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an image forming apparatus that forms an image by electrostatically adhering a developer to a recording medium.

<Prior art> Various devices have been developed to form images according to image information, and some of these devices use conductive magnetic toner, which is a fine powder developer, to electrostatically transfer the toner to a recording medium. There is an imaging device that forms an image by depositing it.

For example, the method shown in Japanese Patent Publication No. 51-46707 has been proposed. As shown in FIG. 8, a non-magnetic cylinder 50
The conductive magnetic toner 5I on the outer periphery of the non-magnetic cylinder 50 is attached to the outer periphery of the cylinder 50 and conveyed by the magnetic field of a rotating magnet 52 provided coaxially with the non-magnetic cylinder 50. Then, the toner 51 is passed through recording electrodes 50a densely arranged along the axial direction on the outer circumferential surface of the non-magnetic cylinder 50, and the conductive layer 53b, A voltage is applied by the power supply section 54 while physically contacting the recording medium 53 formed by laminating the insulating layer (or dielectric layer) 53a. At this time, by applying a voltage corresponding to the image information between the recording electrode 50a and the conductive layer 53b of the recording medium 53, the insulating layer 53 of the recording medium 53 is
An image is formed by attaching toner 51 to a.

Further, as shown in FIG. 9, an image forming apparatus to which the above image forming method is applied is configured such that a recording medium 53 is conveyed by a driving conveyance roller 55a and a driven conveyance roller 55b, and a recording electrode 50a is moved by rotation of a magnet roller 56. The toner 51 is conveyed upward, and an image is formed by attaching or not attaching the toner 51 depending on a signal voltage from the recording control section 57.

For example, the signal voltage from the recording control section 57 is +40V.
When the voltage is applied, the l/ner 51 adheres to the recording medium 53, and when the voltage is 0, it does not adhere. By repeating this operation, image formation is performed.

After the image is displayed in the image display area 58, the toner 51 adhering to the recording medium 53 is rubbed by a cleaning member 59 made of conductive carbon fiber, conductive resin, conductive rubber, etc. roller 5
6 and is transported again in preparation for the next recording.

<Problems to be Solved by the Invention> However, in the above configuration, since the cleaning member 59 scrapes off and collects the toner 51 by rubbing against the recording medium 53, there is a problem described below.

When the cleaning member 59 rubs against the recording medium 53, an electric charge is generated on the recording medium 53 due to frictional charging.
When the toner 51 passes near the magnet roller 56, the toner 51 is attracted by the electric charge and the surface of the recording medium 53 is smeared, which may cause so-called fogging.

The amount of charge on the recording medium 53 depends more on humidity than on temperature in an environment where the temperature is 40° C. or less, and as shown in FIG. 10, the amount of charge increases as the humidity decreases.

On the other hand, the recording medium 5
By applying a bias voltage having a polarity opposite to the frictional charging polarity of No. 3, the amount of charging described above can be suppressed.

However, the above-mentioned image forming apparatus is often used as a display not only indoors but also outdoors, and the temperature inside the apparatus may exceed 40°C, especially when the image display area 58 is exposed to direct sunlight. be.

In this case, the surface of the recording medium 53 is activated and is in a state where the static electricity removal speed is fast and it is difficult to charge.

At this time, for example, in an environment where the humidity is 10% or less, the appropriate bias voltage to be applied to the cleaning member 59 indoors is -5V to -7V, whereas the appropriate bias voltage outdoors is +2V to -2V.

Therefore, if the above-mentioned image forming apparatus is used outdoors and the bias voltage used indoors is applied, an excessive negative charge is injected into the recording medium 53, and there is a risk that the toner 51 will adhere to it and cause dusting. was there.

An object of the present invention is to prevent fog from occurring on the recording medium by changing the bias voltage applied to the cleaning member in response to changes in environmental conditions such as temperature, thereby forming an image that can be used in a wider range of environments. The goal is to provide equipment.

<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 a recording electrode for applying a voltage to a developer according to image information. , a recording medium to which the developer is attached to form an image; a developer supply means for supplying the developer between the recording electrode and the recording medium; a cleaning member for removing the developer, a detection means for detecting the temperature inside the apparatus, and a bias for changing the bias voltage applied to the cleaning member according to the temperature detected by the detection means. and the biasing means sequentially includes reducing a fluctuation width of the bias voltage applied to the cleaning member when the temperature inside the apparatus is high.

<Operation> According to the above configuration, when the temperature inside the apparatus is high, the bias means makes the range of fluctuation of the bias voltage applied to the cleaning member smaller than when the temperature inside the cleaning member is low.

As a result, even if environmental conditions change, an excessive bias voltage is not applied to the cleaning member, and it is possible to prevent developer from floating on the recording medium.

<Embodiment> An embodiment of an image forming apparatus to which the present invention is applied will be described below with reference to the drawings.

Fig. 1 is a cross-sectional explanatory diagram showing a schematic configuration of an image forming apparatus, Fig. 2 is a perspective explanatory diagram of a recording electrode, Fig. 3 is a partially enlarged cross-sectional view of a recording medium, and Fig. 4 is a temperature and humidity inside the apparatus. FIG. 5 is a flowchart showing the operation of the biasing means, and FIG. 6 is a graph showing the relationship between humidity and bias voltage.

First, the schematic structure of the image forming apparatus will be described with reference to FIGS. 1 to 3.

In FIG. 1, reference numeral 1 denotes a recording electrode for applying a voltage to the developer in accordance with image information. This recording electrode 1. teeth,
A convex portion 3a on the outer peripheral surface of a non-magnetic cylinder 3, which is a developer supply means for supplying a conductive magnetic developer (hereinafter referred to as "r-toner") 2, is closely spaced along the axial direction. ing.

As shown in FIG. 2, the recording electrode 1 is connected to a drive element 1b provided on the substrate 1a, and the convex portion 3a
Of the recording electrodes 1, a recording section IC that contributes to recording is arranged. Further, a plurality of holes 1d are bored in the substrate 1a along the axial direction of the non-magnetic cylinder 3. These holes 1d are configured so that the toner 2 conveyed on the outer periphery of the non-magnetic cylinder 3 passes in the direction of arrow A and reaches the recording section IC. Further, the substrate 1a is a flexible printed circuit board, and the drive element 1b
A VFD driver (Oki Electric MSGII63) is used.

As shown in FIG. 1, a rotating magnet 4 that is rotationally driven by a drive motor 4a is coaxially attached to the non-magnetic cylinder 3. The toner 2 is attached to the outer circumferential surface of the non-magnetic cylinder 3 and transported by the 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 held between a tension roller 6a and a drive roller 6b, which are arranged in pairs on the upper and lower sides and serve as conveyance means. The drive roller 6b is rotationally driven by a drive motor (not shown) and conveys the recording sheet 5 in the direction of arrow B in FIG.

As shown in FIG. 3, the recording sheet 5 includes a surface layer 5a made of a transparent abrasive material mainly composed of butyral resin or lanthanum resin, a colored inorganic substance and a binder (acrylic resin, plastic resin). A conductive layer 5c made of vapor-deposited aluminum or ITO (indium and tin oxide) to provide conductivity, and a base material 5d made of a plastic resin such as polyethylene terephthalate, polyethylene, or polypropylene are polymerized. It is made up of:

The surface layer 5a and the colored layer 5b are electrically insulated, and the colored layer 5b is made of titanium oxide (TiOz) and aluminum oxide (A
j! Inorganic materials such as 203) are used.

Reference numeral 7 denotes a recording control section for applying a voltage to the recording electrode 1 according to image information. This recording control section 7 is
A signal voltage corresponding to image information is applied to the conductive layer 5C of the recording sheet 5 to cause the toner 2 to adhere to the surface layer 5a to form an image.

8 is an image display section for externally displaying the image formed on the recording sheet 5, and 9 is a cleaning member attached to the back plate 10 of the main body of the apparatus via a support member 10a. This cleaning member 9 is composed of a cleaning member main body 9a and a soft and conductive brush 9b,
By rubbing the recording sheet 5 with the brush 9b at an appropriate angle and distance, the toner 2 adhering to the recording sheet 5 is scraped onto the non-magnetic cylinder 3. The cleaning member 9 may include carbon fiber,
Materials such as flexible plastics (polyethylene, polypropylene), urethane rubber, silicone, etc., which have conductivity through compounding, are used.

Further, a non-magnetic member 11 and a magnet I2 for supporting the recording sheet 5 are disposed at a position facing the cleaning member 9 with the recording sheet 5 interposed therebetween.

The toner 2 attached to the outer circumference of the non-magnetic cylinder 3 by the rotating magnet 4 is conveyed onto the recording electrode 1 through the hole 1d of the substrate 1a. At this time, by applying a 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 convex portion 3a of the non-magnetic cylinder 3 and is deposited on the recording sheet 5.
It does not affect the image formed.

The image formed on the recording sheet 5 is transferred to the drive roller 6
By the rotation b, the recording sheet 5 is conveyed in the direction of arrow B in FIG. 1, and when it passes through the image display section 8, it is displayed on the outside. The recording sheet 5 that has passed through the image display section 8 is stripped of the attached toner 2 by the cleaning member 9, and the toner 2 falls onto the non-magnetic cylinder 3 and is conveyed again to the next page. Prepare for records.

Further, below the image display section 8 (point C in the figure), a temperature sensor 13 for detecting the temperature inside the device is installed on the back plate 10.
are each provided with a humidity sensor 14 for detecting the humidity inside the device. Further, the back plate 10 is provided with a sensor control board 15 for applying a bias voltage having a polarity opposite to the charge on the recording sheet 5 to the cleaning member 9 according to temperature and humidity. The temperature sensor 13 and the humidity sensor 14 have resistance values that change depending on the temperature and humidity inside the device, and the sensor control board 15 converts the change in resistance value into voltage. The sensor control board 15 is connected to the cleaning member main body 9a, and erases the charging history of the recording sheet 5 by applying a bias voltage to the cleaning member 9 according to the humidity detected by the humidity sensor 14. It is something to do.

Next, a block diagram of a detection means for detecting the temperature and humidity inside the apparatus and a bias means for the cleaning member will be explained with reference to the fourth part.

The temperature and humidity information detected by the temperature sensor 13 and humidity sensor 14 are sent to the sensor control board 1.
5 and is converted into voltage. The voltage value output from this sensor control board 15 is controlled by an output control unit 1 for applying an appropriate voltage to the cleaning member 9.
6, the voltage is converted to an appropriate voltage value, and the cleaning member 9
Apply bias voltage to .

The control operation of the bias means will be explained with reference to the flowchart shown in FIG.

In steps S1 and S2, when the image forming operation is started, the temperature inside the apparatus is detected by the temperature sensor 13.

Then, the process proceeds to step S3, where it is determined whether the temperature inside the apparatus is 40° C. or higher in the case of this embodiment.

If the temperature inside the device is below 40°C, step S4
Then, the humidity inside the device is detected by the humidity sensor 14. The humidity information detected by the humidity sensor 14 is converted into a voltage value by the sensor control board 15 in step S5.

Further, the process proceeds to step S6, and the above voltage value is set to the output control section 1.
6 is converted into an appropriate voltage value to be applied to the cleaning member 9. FIG. 6 shows the correlation between the appropriate voltage value to be applied to the cleaning member 9 and humidity. The shaded area in the figure shows the appropriate voltage value.

Next, the process proceeds to step S7, and it is determined whether or not the image forming operation is finished. If it is not finished, the process returns to step S3 again to continue the image forming operation.

Further, in step S3, if the temperature inside the device is 40°C or higher, the process proceeds to step S8, and the temperature sensor 1
The temperature information detected by 3 is input to the sensor control board 15, and the output control unit 16 sets a bias voltage of 0 ± 4 V, preferably 0 ± 2, which is a bias width smaller than when the temperature is 40°C or less. is applied to the cleaning member 9 regardless of humidity.

Then, the process proceeds to step S7, where it is determined whether or not the image forming operation is completed, and if it is not completed, step S3 is performed again.
to continue the image forming operation.

Incidentally, the volume resistivity value of the recording sheet 5 used in this example was 1.0 in the humidity range of 90% to 10%. OXlO7Ω・cm to 1
．． The volume resistivity of toner 2 is 1.0 XlO7Ω·can at 50% humidity. OXl06Ω・cm to 1. OXIO3Ω
・Changed to cIn.

Further, the above-mentioned volume resistivity value refers to a value measured by a method as shown in FIG. That is, by rotating a rotating magnet 18 coaxially provided within a fixed non-magnetic cylindrical sleeve 17 in the direction of arrow F, the toner 2 is transferred to the sleeve 17.
conveyed along the circumferential surface. The rotational speed of the rotating magnet 18 at this time is 1300 to 1800 r with 12 magnetic poles.
pm is set. Further, a non-magnetic rotating sleeve 19 is provided opposite to the non-magnetic cylindrical sleeve 17, and extends from 1300 to 1800 in the same direction as the rotating magnet 18.
It rotates at a speed of rpm.

Further, a recording electrode 20 is provided on the circumferential surface of the non-magnetic cylindrical sleeve 17 so as to face the rotating sleeve 19. The distance d between this recording electrode 20 and the rotating sleeve 19
is 0.2 mm, and the area S of the recording electrode 20 is 1 c.
+++2 (5cm x 0.2cm).

In the above configuration, the current i flowing between the cylindrical sleeves 17 and 19
By measuring the voltage and the voltage, the resistance R and the volume resistance value ρ can be calculated.

p-V/iXs/d (Ω・cm:1 = 30/i x 110.2 Xl0= 1/i
X1500 CΩ・cm) In this example, the applied voltage is 3
At 0V, it depends on the type of toner 2, but it is 10μA to 300μA.
The value of ρ-5X106~1.5XIO' was measured.
It was [Ω·cm].

The volume resistivity values calculated by measuring the applied voltage and current using a toner and a recording sheet under environmental conditions of a temperature of 25'C and a humidity of 50% will be exemplified below.

(The following is a blank space) According to the above configuration, when the temperature inside the apparatus is 40'C or less, a bias voltage is applied to the cleaning member 9 according to the humidity, as shown in the graph of FIG. 6. This prevents the recording sheet 5 from being excessively charged, prevents fogging of the toner 2, and maintains image quality.

In addition, even if the device is used outdoors and the temperature inside the device reaches 40'C or higher due to direct sunlight, the bias voltage should be set to 0±4■, more preferably o±2■. With this structure, it is possible to prevent the recording sheet 5 from being excessively charged, and it is possible to expand the range of environments in which the apparatus can be used.

The temperature sensor 13 was installed at the 0 point on the bottom of the image display section 8, which best follows temperature changes within the device, but it could be installed at other locations, such as point D or E in FIG. It is also possible to provide it at a point or the like.

Similarly, the humidity sensor 14 is also attached to the back plate 10, but it can be attached at any location that does not interfere with image formation or display.

In addition, in the above embodiment, the range of bias change was controlled at 40°C, but this largely depends on the electrical characteristics of the recording medium and toner, and if an appropriate temperature is selected as the boundary temperature depending on the material used. good.

Furthermore, in this embodiment, the width of change in bias was controlled by considering humidity in addition to temperature, but excessive charging of the recording medium can be prevented by simply controlling the width of bias for the cleaning member depending on temperature. Therefore, it is possible to greatly contribute to the improvement of image quality even without the control shown in the embodiment regarding humidity.

<Effects of the Invention> As described above, in the present invention, when the temperature inside the apparatus becomes high, a voltage with a smaller fluctuation range is applied to the cleaning member by the bias means than when the temperature is on the low temperature side. Therefore, an excessive bias voltage is not applied to the cleaning member in response to changes in environmental conditions, and it is possible to prevent developer fogging, maintain image quality, and expand the range of environments in which the device can be used. .

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional explanatory diagram showing a schematic configuration of an image forming apparatus, Fig. 2 is a perspective explanatory diagram of a recording electrode, Fig. 3 is a partially enlarged cross-sectional view of a recording medium, and Fig. 4 is a temperature and humidity inside the apparatus. 5 is a flowchart showing the operation of the biasing means, FIG. 6 is a graph showing the relationship between humidity and bias voltage, and FIG. 7 is an explanatory diagram of the apparatus of the experimental example. FIGS. 8 to 10 are explanatory diagrams of conventional examples. 1.20 is a recording electrode, 1a is a substrate, 1b is a driving element, 1
c is a recording part, 1d is a hole, 2 is a toner, 3°17 is a non-magnetic cylinder, 3a is a convex part, 4.18 is a rotating magnet, 5 is a recording sheet, 6a is a tension roller, 6b is a drive roller, 7 is a a recording control section; 8 an image display section; 9 a cleaning member;
9a is a cleaning member main body, 9b is a brush, 10 is a back plate, 10a is a support member, 11 is a non-magnetic member, 12 is a magnet,
13 is a temperature sensor 14 is a humidity sensor, 15 is a sensor control board, 16 is an output control section, and 19 is a rotating sleeve.

Claims (4)

[Claims] (1) A recording electrode for applying a voltage to a developer according to image information, a recording medium to which the developer is attached to form an image, and a developer between the recording electrode and the recording medium. a cleaning member for rubbing the recording medium to remove the adhering developer; a detection means for detecting the temperature inside the apparatus; and bias means for changing the bias voltage applied to the cleaning member according to the temperature of the cleaning member, and the bias means reduces the fluctuation width of the bias voltage applied to the cleaning member when the temperature inside the apparatus is on the high temperature side. An image forming apparatus characterized by: (2) 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. (3) The image forming device further includes a detection means for detecting humidity within the device, and a bias for changing a bias voltage applied to the cleaning member according to the temperature and humidity detected by the detection means. means, the biasing means comprising:
When the temperature inside the device is below a predetermined temperature, the bias voltage applied to the cleaning member is changed according to the humidity, and when the temperature inside the device is above the predetermined temperature, the cleaning is performed regardless of the humidity. The image forming apparatus according to claim 2, wherein the width of application of the bias voltage to the member is made small. (4) The image forming apparatus according to claim 2, wherein the image formed on the recording medium is a display device that is used by displaying the image on a display section.