JP2660597B2 - Image forming device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image forming apparatus for forming an image by electrostatically attaching a developer to a recording medium.

<Conventional technology> Conventionally, various apparatuses for forming an image in accordance with image information have been developed, and a conductive magnetic toner as a fine powder developer is used therein, and the toner is electrostatically applied to a recording medium. 2. Description of the Related Art There is an image apparatus that forms an image by attaching the image.

For example, a method disclosed in Japanese Patent Publication No. 51-46707 has been proposed. As shown in FIG. 8, the conductive magnetic toner 51 on the outer periphery of the non-magnetic cylinder 50 is adhered to the outer peripheral surface of the cylinder 50 by the magnetic field of the rotating magnet 52 provided coaxially with the non-magnetic cylinder 50. Transport. Then, the toner 51 is passed through recording electrodes 50a densely arranged along the axial direction on the outer peripheral surface of the non-magnetic cylinder 50, and the conductive layer 53b is provided from the inner side provided near the non-magnetic cylinder 50. Insulating layer (or conductive layer)
A voltage is applied by the power supply unit 54 when it is in physical contact with the recording medium 53 formed by laminating 53a. At this time, by applying a voltage according to image information between the recording electrode 50a and the conductive layer 53b of the recording medium 53, the toner 51 is adhered to the insulating layer 53a of the recording medium 53 to form an image. is there.

Further, as an image forming apparatus to which the above-described image forming method is applied, as shown in FIG. 9, a recording medium 50 conveyed by a driving conveyance roller 55a and a driven conveyance roller 55b is rotated by a magnet roller 56 to form a recording electrode 50a. Toner on top 5
1 and the toner 5 by the signal voltage from the recording control unit 57.
An image is formed with or without 1 attached.

For example, when the signal voltage from the recording control unit 57 is applied at +40 V, the image is formed by repeating the operation that the toner 51 adheres to the recording medium 53 and does not adhere at 0 V.

The toner 51 adhering to the recording medium 53 is in an image display area.
After the image is displayed at 58, the conductive carbon fiber,
After being rubbed by a cleaning member 59 made of a conductive resin or a conductive rubber or the like, it falls on the magnet roller 56 and is conveyed again to prepare for the next recording.

<Problems to be Solved by the Invention> However, in the above-described configuration, there are the following problems in order for the cleaning member 59 to rub against the recording medium 53 to scrape and collect the toner 51.

When the cleaning member 59 rubs against the recording medium 53,
An electric charge is generated on the recording medium 53 due to the triboelectric charging, and the toner 51 is attracted by the electric charges when passing through the vicinity of the magnet roller 56, so that the surface of the recording medium 53 may be stained.

The charge amount of the recording medium 52 is more dependent on the humidity than the temperature in an environment where the temperature is 40 ° C. or lower. As shown in FIG. 10, the charge amount increases as the humidity decreases. On the other hand, by applying a bias voltage having a polarity opposite to the triboelectric charging polarity of the recording medium 53 to the cleaning member 59, the charge amount can be suppressed.

However, the image forming apparatus is often used not only indoors but also outdoors as a display, particularly when direct sunlight irradiates the image display area 58, the temperature inside the apparatus may exceed 40 ° C. . In this case, the surface of the recording medium 53 is activated, and the static elimination speed is high and it is hard to be charged.

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

Therefore, when a bias voltage is applied when the image forming apparatus is used outdoors when the image forming apparatus is used outdoors, negative charges may be excessively injected into the recording medium 53, and the toner 51 may adhere and fog may occur. there were.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus in which the fogging of the recording medium is prevented by changing a bias voltage applied to a cleaning member at least in accordance with a change in environmental conditions of temperature, and a use environment range is widened. Is to provide.

<Means for Solving the Problem> A typical means for solving the problems of the prior art 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 for forming an image by attaching the developer, a developer supply unit for supplying a developer between the recording electrode and the recording medium, and rubbing and attaching the recording medium. A cleaning member for removing the developer, a detecting unit for detecting a temperature in the apparatus, and a bias for changing a bias voltage applied to the cleaning member according to the temperature detected by the detecting unit. Wherein the bias means reduces the change width of the bias voltage with respect to the cleaning member when the temperature in the apparatus is high.

<Operation> According to the above configuration, when the temperature in the apparatus is high, the fluctuation range of the bias voltage applied to the cleaning member is made smaller than that on the low temperature side by the bias unit.

Thus, even if environmental conditions change, an excessive bias voltage is not applied to the cleaning member,
It is possible to prevent the developer from fogging the recording medium.

Hereinafter, an embodiment of an image forming apparatus to which the present invention is applied will be described with reference to the drawings.

FIG. 1 is an explanatory sectional view showing a schematic configuration of an image forming apparatus;
FIG. 2 is a perspective explanatory view of a recording electrode, FIG. 3 is a partially enlarged sectional view of a recording medium, FIG. 4 is a block diagram of a detecting means for detecting temperature and humidity in the apparatus, and FIG. FIG. 6 is a graph showing the relationship between humidity and bias voltage.

First, a schematic configuration of the image forming apparatus will be described with reference to FIGS.

In FIG. 1, reference numeral 1 denotes a recording electrode for applying a voltage to a developer according to image information. This recording electrode 1
The conductive magnetic developer (hereinafter, referred to as “toner”) 2 is densely mounted along the axial direction on a convex portion 3 a on an outer peripheral surface of a non-magnetic cylinder 3 which is a developer supply unit for supplying a developer.

As shown in FIG. 2, the recording electrode 1 is connected to a driving element 1b provided on a substrate 1a, and a recording portion 1c of the recording electrode 1 which contributes to recording is arranged on the convex portion 3a. ing. A plurality of holes 1d are formed in the substrate 1a along the axial direction of the non-magnetic cylinder 3. These holes 1d
The toner 2 conveyed on the outer circumference of the non-magnetic cylinder 3 is configured to pass in the direction of arrow A and reach the recording unit 1c. The board 1a is a flexible printed board, and the drive element 1b is a VFD driver (MSG1163 manufactured by Oki Electric).

As shown in FIG. 1, a rotary magnet 4 rotatably driven by a drive motor 4a is coaxially attached to the non-magnetic cylinder 3. The magnetic field formed by the rotating magnet 4 causes the toner 2 to adhere to the outer peripheral surface of the non-magnetic cylinder 3 and is transported.

In the vicinity of the recording electrode 1, a recording sheet 5 in the form of an endless belt, which is a recording medium for forming an image by adhering the toner 2, is arranged with a part thereof close to each other. The recording sheet 5 is stretched between a tension roller 6a and a drive roller 6b, which are disposed as a pair at the top and bottom, which are conveying means. The drive roller 6b is driven to rotate 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 is composed of a surface layer 5a made of a transparent material containing butyral resin or urethane resin as a main component, a colored inorganic substance and a binder (acrylic resin, plastic resin). A colored layer 5b, a conductive layer 5c on which aluminum or ITO (oxide of indium and tin) for imparting conductivity is deposited, and a base material 5d made of a plastic resin such as polyethylene terephthalate, polyethylene, or polypropylene. It is configured.

The surface layer 5a and the colored layer 5b are electrically insulated. As the colored layer 5b, titanium oxide (TiO ₂ ), aluminum oxide (Al
Inorganic substances such as ₂ O ₃ ) are used.

Reference numeral 7 denotes a recording control unit for applying a voltage to the recording electrode 1 according to image information. This recording control unit 7
Is to apply a signal voltage corresponding to the image information to the conductive layer 5c of the recording sheet 5 to adhere the toner 2 on the surface layer 5a to form an image.

Reference numeral 8 denotes an image display unit for displaying an image formed on the recording sheet 5 to the outside, and reference numeral 9 denotes a cleaning member attached to a back plate 10 of the apparatus main body via a support member 10a. The cleaning member 9 is composed of a cleaning member main body 9a and a soft and conductive brush 9b. The brush 9b is rubbed on the recording sheet 5 at an appropriate angle and distance, so that the brush 9b is placed on the recording sheet 5. The attached toner 2 is scraped off onto the non-magnetic cylinder 3. The cleaning member 9 is made of a material such as carbon fiber, soft plastic (polyethylene, polypropylene), urethane rubber, or silicon having conductivity by compounding.

A non-magnetic member 11 and a magnet 12 for supporting the recording sheet 5 are provided at a position facing the cleaning member 9 via the recording sheet 5.

The toner 2 adhered to the outer periphery of the non-magnetic cylinder 3 and transported by the rotating magnet 4 passes through the hole 1d of the substrate 1a and is transported onto the recording electrode 1. 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. still,
The toner 2 that did not contribute to image formation on the recording electrode 1
It does not drop from the convex portion 3a of the non-magnetic cylinder 3 and does not affect the image formed on the recording sheet 5.

The image formed on the recording sheet 5 is a driving roller
The recording sheet 5 is conveyed in the direction of arrow B in FIG. 1 by the rotation of 6b, and is displayed outside when passing through the image display unit 8. Then, the recording sheet 5 that has passed through the image display section 8 is stripped of the attached toner 2 from the cleaning member 9, and the toner 2 falls onto the non-magnetic cylinder 3 and is conveyed again, and Prepare for the record.

Further, below the image display unit 8 (point C in the figure), a temperature sensor 13 for detecting the temperature inside the apparatus and a humidity sensor 14 for detecting the humidity inside the apparatus are provided on the back plate 10, respectively. Is provided. 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 the temperature and humidity. The temperature sensor 13 and the temperature sensor 14 change their resistance values according to the temperature and humidity in the device.
Converts the change in the resistance value into a voltage. The sensor control board 15 is connected to the cleaning member body 9a, and erases the charging history of the recording sheet 5 by applying a bias voltage to the cleaning member 9 in accordance with the humidity detected by the humidity sensor 14. Is what you do.

Next, a block diagram of a detecting unit for detecting the temperature and the humidity in the apparatus and a bias unit for the cleaning member will be described with reference to FIG.

The temperature and humidity information detected by the temperature sensor 13 and the humidity sensor 14 are input to a sensor control board 15 and converted into a voltage. The voltage value output from the sensor control board 15 is converted into an appropriate voltage value by an output control unit 16 for applying an appropriate voltage to the cleaning member 9, and a bias voltage is applied to the cleaning member 9.

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

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

Then, proceeding to step S3, it is determined whether or not the temperature inside the apparatus is equal to or higher than 40 ° C. in the case of the present embodiment. If the temperature inside the device is equal to or lower than 40 ° C., the process proceeds to step S4, and the humidity inside the device is detected by the humidity sensor. The humidity information detected by the humidity sensor 14 proceeds to step S5, where it is converted into a voltage value in the sensor control board 15. In step S6, the output controller 16 converts the voltage value into an appropriate voltage value to be applied to the cleaning member 9. FIG. 6 shows a correlation between an appropriate voltage value to be applied to the cleaning member 9 and humidity. A region surrounded by oblique lines in the drawing indicates an appropriate voltage value.

Next, the process proceeds to step S7 to determine whether or not the image forming operation is completed. If not, the process returns to step S3 to continue the image forming operation. In step S3,
If the temperature in the apparatus is equal to or higher than 40 ° C., the process proceeds to step S8, and the temperature information detected by the temperature sensor 13 is input to the sensor control board 15, and is smaller than the temperature lower than 40 ° C. by the output control unit 16. 0V ± which is the width bias
A bias voltage of 4V, preferably 0V ± 2V is applied to the cleaning member 9 regardless of humidity.

Then, the process proceeds to step S7 to determine whether the image forming operation is completed. If not, the process returns to step S3 to continue the image forming operation.

The volume resistivity of the recording sheet 5 used in the present embodiment ranges from 1.0 × 10 ⁷ Ω · cm to 1.0 × 10 ⁹ Ω · cm in a humidity range of 90% to 10%.
cm, and the volume resistance of Toner 2 is 50% humidity.
And 1.0 × 10 ⁷ Ωcm, 1.0 × 10 ⁶ Ωcm to 1.0 × 1
0 was changed to ^{8 Ω} · cm.

The above-mentioned volume resistance value means a value measured by a method as shown in FIG. That is, the toner 2 is conveyed along the peripheral surface on the sleeve 17 by rotating the rotary magnet 18 provided coaxially in the fixed non-magnetic cylindrical sleeve 17 in the direction of arrow F. The rotation speed of the rotating magnet 18 at this time is set to 1300 to 1800 rpm with 12 magnetic poles.
A non-magnetic rotating sleeve 19 is provided so as to face the non-magnetic cylindrical sleeve 17, and rotates at a speed of 1300 to 1800 rpm in the same direction as the rotating magnet 18. Further, a recording electrode 20 is provided on the peripheral surface of the non-magnetic cylindrical sleeve 17 so as to face the rotary sleeve 19. This recording electrode
The distance d between the rotation sleeve 20 and the rotary sleeve 19 is 0.2 mm, and the area S of the recording electrode 20 is set to 1 cm ² (5 cm × 0.2 cm).

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

ρ = V / i × S / d [Ω · cm] = 30 / i × 1 / 0.2 × 10 ⁻¹ = 1 / i × 1500 [Ω · cm] In this embodiment, the type of toner 2 is set at an applied voltage of 30 V. Although it depends, a value of about 10 μA to 300 μA is measured, and ρ = 5 × 10 ⁶ ~
It was 1.5 × 10 ⁸ [Ω · cm].

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

According to the above configuration, when the temperature in the apparatus is 40 ° C. or less, as shown in the graph of FIG. 6, the bias voltage is applied to the cleaning member 9 in accordance with the humidity, so that the recording sheet 5 Is not excessively charged, fog of the toner 2 can be prevented, and image quality can be maintained.

Also, by using the device outdoors, even if it is exposed to direct sunlight and the temperature inside the device becomes 40 ° C. or higher, the bias voltage is set to 0V ± 4V, more preferably 0V ± 2V. It is possible to prevent the sheet 5 from being excessively charged and to widen the range of use environment of the apparatus.

The mounting position of the temperature sensor 13 was set at point C on the lower side of the image display section 8, which most closely follows the temperature change in the apparatus. However, other places such as point D and point E in FIG. Can also be provided. Similarly, the humidity sensor 14 is attached to the back plate 10, but can be attached to a place where there is no hindrance to image formation or display.

Further, in the above embodiment, the variation width of the bias was controlled at the boundary of 40 ° C., but this largely depends on the electrical characteristics of the recording medium and the toner, and an appropriate value may be selected as the boundary temperature depending on the material used. .

Further, in the present embodiment, the width of the bias change is controlled in consideration of the humidity in addition to the temperature. However, it is possible to prevent the recording medium from being excessively charged only by controlling the bias width for the cleaning member due to the temperature. Therefore, it is possible to greatly contribute to improvement of the image quality without the control shown in the embodiment relating to the humidity.

<Effect of the Invention> As described above, according to the present invention, when the temperature in the apparatus is increased by the bias unit, a voltage having a smaller fluctuation width than that at the low temperature side is applied to the cleaning member. Therefore, no excessive bias voltage is applied to the cleaning member in accordance with changes in environmental conditions,
Prevents fogging of developer and maintains image quality,
The use environment range of the device can be expanded.

[Brief description of the drawings]

FIG. 1 is a cross-sectional explanatory view showing a schematic configuration of an image forming apparatus, FIG. 2 is a perspective explanatory view of a recording electrode, FIG. 3 is a partially enlarged cross-sectional view of a recording medium, and FIG. FIG. 5 is a flowchart showing the operation of the biasing means, FIG. 6 is a graph showing the relationship between humidity and bias voltage, FIG. 7 is an explanatory diagram of the apparatus of the embodiment, 8 to 10 are explanatory diagrams of a conventional example. 1, 20 are recording electrodes, 1a is a substrate, 1b is a driving element, 1c 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 are rotating magnets, Is a recording sheet, 6a is a tension roller, 6b is a driving roller, 7 is a recording control unit, 8 is an image display unit, 9 is a cleaning member, 9a is a cleaning member main body, 9b is a brush, 10 is a back plate, and 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 unit,
19 is a rotating sleeve.

Continuation of the front page (56) References JP-A-63-249182 (JP, A) JP-A-60-7457 (JP, A) JP-A-2-216177 (JP, A) JP-A-3-33884 (JP) JP-A-1-130178 (JP, A) JP-A-61-67073 (JP, A) JP-A-63-249184 (JP, A) JP-A-63-18384 (JP, A) 57-26885 (JP, A) JP-A-57-63535 (JP, A) JP-A-62-234180 (JP, A) JP-B-51-46707 (JP, B2)

Claims (4)

(57) [Claims] A recording electrode for applying a voltage to the developer according to image information; a recording medium for forming an image by attaching the developer; and a recording medium between the recording electrode and the recording medium. A developer supply unit for supplying a developer, a cleaning member for removing the developer adhered by rubbing the recording medium, a detection unit for detecting a temperature in the apparatus, and the detection unit Bias means for changing a bias voltage applied to the cleaning member in accordance with the temperature detected by the apparatus, wherein the bias means has a change width of the bias voltage with respect to the cleaning member when the temperature in the apparatus is high. An image forming apparatus comprising: 2. The image forming apparatus according to claim 1, wherein said recording medium has a surface transparent resin layer, a colored inorganic substance, and a conductive layer in that order. 3. The image forming apparatus according to claim 1, further comprising: detecting means for detecting humidity in the apparatus, and changing a bias voltage applied to the cleaning member in accordance with the temperature and humidity detected by the detecting means. When the temperature in the apparatus is equal to or lower than a predetermined temperature, the bias means changes a bias voltage applied to the cleaning member in accordance with humidity, and the temperature in the apparatus becomes a predetermined temperature. The image forming apparatus according to claim 2, wherein when the temperature is equal to or higher than the temperature, the application width of the bias voltage to the cleaning member is reduced regardless of the humidity. 4. The display device according to claim 2, wherein the image formed on the recording medium is used by displaying it on a display unit.
The image forming apparatus as described in the above.