JP2002099181A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus which can prevent stacked toner from scattering, collect residual toner generated in an image forming process, and efficiently reuse it. SOLUTION: This color image forming apparatus 2: is equipped with an imaging means for forming an image on a transfer material 25 through developing, transferring, and fixing processes and which can operate in Braille output mode in addition to a normal output mode; repeats development a plurality of times when the Braille output mode is selected and performs transfer and fixation for a transfer material 25 through a return path 34 for putting the transfer material 25 back to a paper feed path 27 each time development is performed; is provided with a developing device 13P exclusively used for the Braille output mode as a developing device for development in addition to developing devices 13Y, 13M, 13C, and 13k for the normal output mode and; is further provided with a toner circulator 51 which collects the residual toner generated in the process for forming the image and reuses the toner for the development.

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 adopting an electrophotographic system and capable of outputting Braille.

[0002]

2. Description of the Related Art An image forming apparatus adopting an electrophotographic system and capable of outputting Braille is disclosed in Japanese Patent Application Laid-Open No. 8-63039. This image forming apparatus can switch between a Braille output mode in which a toner image has a convex shape on a transfer sheet and a normal color image output. In the Braille output mode, a convex toner image having a larger height is used. Is formed so that the toner images are superimposed many times to obtain

[0003]

In the case of the above-described conventional image forming apparatus, the toner image is merely superposed many times so that the toner image has a predetermined height. There is a problem that toner is scattered even if it is held on transfer paper or an intermediate transfer member. SUMMARY OF THE INVENTION The present invention has been made to solve the above-described conventional problems, and it is possible to prevent scattering of superimposed toner, collect residual toner generated in an image forming process, and efficiently reuse the toner. It is an object of the present invention to provide an image forming apparatus which enables the above.

[0004]

In order to solve the above-mentioned problems, a first invention comprises an image forming means for forming an image on a transfer material through development, transfer and fixing processes. In addition, in the image forming apparatus formed to be operable in the Braille output mode, when the Braille output mode is selected, the development is repeated a plurality of times, and for each development,
The transfer and fixing are performed on the transfer material.

According to a second aspect of the invention, in addition to the configuration of the first aspect, a developing device for the Braille output mode is provided as the developing device for the development in addition to the developing device for the normal output mode. Configuration.

Further, the third invention has, in addition to the constitution of the first or second invention, a toner circulator for recovering residual toner generated in the process of forming the image and reusing it for the development. The configuration was adopted.

Further, in the fourth invention, in addition to the constitution of any one of the first to third inventions, the fixing strength at the time of selecting the Braille output mode is higher than that at the last fixing. Is controlled so as to further reduce the strength.

In a fifth aspect of the present invention, in addition to any one of the first to third aspects, the absolute value of the initial charging potential of the surface of the photosensitive member to be exposed for the development is changed to the Braille output mode. At the time of the operation in, the configuration is made lower than in the case of the normal output mode.

In a sixth aspect of the present invention, in addition to any one of the first to third aspects, the absolute value of the developing bias used for the development is determined when the device is operated in the Braille output mode.
It is configured to be higher than in the case of the normal output mode.

In a seventh aspect of the present invention, in addition to any one of the first to third aspects, the intensity of exposure from an exposure device for exposing the surface of the photoreceptor for the development is output by the Braille output. During operation in the mode, the configuration is made stronger than in the normal output mode.

In an eighth aspect of the present invention, in addition to any one of the first to seventh aspects, the relative speed between the developing device and the photosensitive member which has been developed by the developing device is set to At the time of operation in the Braille output mode, it is configured to increase compared to the case of the normal output mode.

In a ninth aspect of the present invention, in addition to the configuration of the second or third aspect, the developing device for the Braille output mode has a toner viscosity larger than that of the other developing devices.

[0013]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a color image forming apparatus 1 according to a first embodiment of the present invention. The color image forming apparatus 1 includes an exposure device 11, a photoconductor 12, a developing device 13Y,
13M, 13C, 13K, an intermediate transfer belt 14, a paper cassette 15 for paper feeding, a fixing device 16, and a paper discharging unit 17. The exposure device 11 exposes the photoconductor 12 by laser beam irradiation in accordance with an image signal input from a device (not shown). On the other hand, the photosensitive member 12 is
The surface layer is uniformly charged by 1 and an electrostatic latent image is formed on the surface layer by the exposure.

Developing devices 13Y, 13M, 13C, 13K
Are arranged on a rotatably provided rack 22, and are respectively a non-magnetic one-component developer such as yellow toner (Y), magenta toner (M), and cyan toner (C).
And one type of flux toner (K). Then, first, the photoconductor 12 is
The electrostatic latent image corresponding to the yellow color above is developed.
An intermediate transfer belt 14 is provided so as to be in close contact with the photoreceptor 12 and to operate in accordance with the peripheral speed of the photoreceptor 12, and the obtained yellow toner image is transferred to the intermediate transfer belt 14.

After the transfer, the photoreceptor 12 is cleaned by scraping off the residual toner on the surface thereof with a blade provided in a cleaner box 24 and the rack 22 is cleaned.
Is rotated 90 degrees and the developing device 1 is substituted for the developing device 13Y.
3M faces the photoconductor 12. Subsequently, development and transfer of the magenta toner are performed in the same manner as in the case of the yellow toner described above. Further, development and transfer of the cyan toner and the black toner are sequentially performed in the same manner as described above. In this way, after forming an electrostatic latent image corresponding to each color on the photoreceptor 12, development is performed, and each color is sequentially superimposed and transferred onto the intermediate transfer belt 14 to form a full-color toner image. .

A transfer material 25 is stored in the paper cassette 15, and a paper passage 27 formed by a guide member 26 extends from the paper cassette 15. A pair of timing rollers 28 is provided in the paper passage 27, and a transfer roller 29 facing the intermediate transfer belt 14 is provided. Then, the transfer material 25 is passed through the paper passage 27,
When the toner image is sent out by the timing roller 28, the toner image formed on the intermediate transfer belt 14 is collectively transferred to the transferred transfer material 25 at the position of the transfer roller 29 to form a full-color toner image. . Thereafter, the intermediate transfer belt 14 is cleaned by scraping off the untransferred residual toner thereon with a blade provided in the cleaner box 24.

The toner image transferred onto the transfer material 25 by the 29 secondary transfer rollers is heated by a fixing device 16 comprising a pair of a heating roller 16A and a pressure roller 16B provided in a paper passage 27. Then, it is melted and fixed to form a printed image. Incidentally, the color image forming apparatus 1 is formed so as to be operable in a Braille output mode in addition to the normal output mode, and the normal output mode or the Braille output mode is selected by mode selection means (not shown). The control is switched in the color image forming apparatus 1 in accordance with the normal output mode or the Braille output mode. Further, a path switching unit 31 is provided at a portion of the paper passage 27 beyond the fixing device 16, and the paper passage 27 is divided into two branch paths. One of the branch paths reaches the paper discharge port 32, and the other returns to the paper path 27 of the timing roller 28, where it joins. That is, a return path 3 formed by a plurality of guide members 33 extending from the path switching means 31 and returning to the paper path 27.
The return path 34 is formed with a plurality of pairs of feed rollers and the return path 34 and the intermediate roller 35
After joining.

When the Braille output mode is selected by the mode selection means, the path switching means 31 is operated, and the transfer material 25 having passed through the fixing device 16 is returned to the return path 34.
Will be led to. Further, the transfer material 25 that has entered the return path 34 travels along the return path 34 and the paper passing path 2.
7 is conveyed to the junction. During this time, an image equivalent to the previously formed image is formed on the photoconductor 12 through the above-described charging, exposing, and developing processes. Then, the transfer material 25 returned to the paper path 27 again through the confluence section is sent out by the timing roller 28, and an equivalent image is repeatedly formed at the position of the image already formed on the transfer material 25. The transfer material 25 is transferred to the fixing device 16 after the transfer. Further, the transfer material 25 that has exited the fixing device 16 passes through the feedback path 34 a predetermined number of times, and repeats the above-described development, transfer, and fixing processes. Thereafter, the path switching unit 31 operates, and the transfer material 25 is discharged. The paper is sent out from the opening 32 onto the paper discharge tray.

In the above-described image forming process, the transfer material 2
5 passes the fixing device 16 a plurality of times, and fixing is performed each time. Regarding the fixing strength at this time, it is preferable that the fixing strength in the previous fixing is lower than that in the final fixing. The reason for this is that, in order to print Braille on the transfer material 25 with toner in a smaller number of times, the necessary fixing requirement is to prevent the toner from separating or scattering during the transfer material transfer or the transfer process. It is preferable to avoid excessive melting.

Here, the Braille output means an output for forming a convex portion on the transfer material 25 with toner instead of forming a convex portion on the transfer material 25 itself.
As shown in FIG. 2, the cross-sectional shape of the toner fixed on the transfer material 25, that is, the cross-sectional shape of the point 41 forming the Braille, is such that the toner diameter D is 1-2 mm and the toner height H is 0.3-0. .6
It is desirable to have a convex shape of about mm. For example, when fixing is performed twice, the area of the point 41B printed at the time of the second fixing shown in FIGS. 4 and 5 is compared with the area of the upper and lower surfaces of the point 41A at the time of the first fixing shown in FIG. By reducing the area of the upper and lower surfaces, the sectional shape of the point 41 shown in FIG. 2 is obtained. Fixing may be performed three or more times, and in this case also, it is desirable to reduce the cross-sectional area of a point printed by fixing performed later.

FIG. 6 shows an example of the fixing device 16 for changing the area of the printed point. At the time of fixing before the final printing, as shown by a two-dot chain line, a solenoid 16C for pushing the pressing roller 16B is provided. In the contracted state, the pressure roller 16B is kept in light contact with the heating roller 16A. On the other hand, at the time of final fixing, as shown by the solid line, the solenoid 16C is extended by ΔL, and the pressure roller 16B is pressed against the heating roller 16A.

By the way, with respect to the shape of the point 41 in Braille shown in FIG.
The toner diameter D is about 1 to 2 mm, and the toner height H is smaller than the above-mentioned 0.3 to 0.6 mm. However, the toner height H of about 0.3 to 0.6 mm can be obtained by the development, transfer, and fixing processes described above a plurality of times. And control for appropriately adjusting any of the exposure conditions. It is possible to obtain the toner height H of the above-mentioned size.

When a desired toner height is to be obtained, a development corresponding to the toner height is applied to a portion of the photoconductor surface whose potential has been changed by exposure to the photoconductor surface charged to a predetermined initial potential in advance. The charged toner is developed so as to cancel the potential gap determined by the potential. FIG. 7 shows the relationship between the exposure intensity on the photoreceptor surface, the potential of the photoreceptor surface (photoreceptor potential) changed by the exposure, the developing gap, and the height of the toner developed on the transfer material.
The relationship shown in FIG. That is, when the exposure intensity increases, the absolute value of the photoconductor potential decreases, and when the absolute value of the photoconductor potential decreases, the potential gap increases. When the potential gap increases, the toner height increases until the toner reaches the saturation limit. Note that the alternate long and short dash line in FIG. 7 indicates that the toner height H can be obtained with respect to the input I of the exposure intensity indicated by the inverted triangle on the horizontal axis.

Therefore, as shown in FIG. 8, by giving an input I ₂ of a higher exposure intensity to an input I ₁ of an exposure intensity corresponding to the toner height H ₁ , a larger toner height H _{2 is obtained.} Can be obtained. In the Braille output mode, as compared with the case of the initial charging potential of the photoconductor in the normal output mode indicated by the two-dot chain line in FIG. By setting the potential, the height of the toner can be increased. further,
In the Braille output mode, as compared with the potential gap in the normal output mode indicated by the two-dot chain line in FIG. 10, the absolute value of the developing potential is increased to increase the potential gap as indicated by the solid line. As a result, the height of the toner can be increased.

In addition, in the Braille output mode, as compared with the development characteristics in the normal output mode shown by the two-dot chain line in FIG. Can be increased. Note that FIG.
In to 11, and a one-dot chain line, for the same input I, the toner height in the normal output mode that is H _1,
The Braille output mode indicates that the larger toner height H ₂ can be obtained.

By the way, as shown in FIG. 11, for example, the change speed at which the toner height increases with an increase in the potential gap becomes slow, and the toner height eventually becomes saturated and does not change. In such a state, by increasing the relative speed of the developing roller with respect to the photoconductor in the developing device, the toner conveying capacity per unit time is increased, so that the toner height can be increased.

Further, in order to emphasize the convex shape of a point in Braille, for example, as shown in FIG. 12, the distribution density of a large number of dots D forming the point 41 is increased by approaching the center of the point 41.
What is necessary is just to control the dot density so that it becomes larger. Further, as shown in FIG. 13, the convex shape can be emphasized by controlling the dot area so that the diameter of the dot D increases as the point 41 approaches the center. The dot area can be increased by increasing the output of the exposure laser beam. As described above, one of the above-described various factors is controlled or two or more factors are appropriately combined and controlled in accordance with each of the fixing processes repeated a plurality of times in the case of the Braille output mode. Thereby, a good Braille image can be obtained.

FIG. 14 shows a color image forming apparatus 2 according to a second embodiment of the present invention. Portions common to those of the color image forming apparatus 1 shown in FIG. I do. In this color image forming apparatus 2,
A Braille developing device 13P is provided in addition to the developing devices 13Y, 13M, 13C, and 13K. When the Braille output mode is selected, the rack 22 rotates, and the Braille developing device 13P is carried to the developing position facing the photoconductor 12.

FIG. 15 shows a point 41 on the transfer material 25 when the normal output mode toner is used.
FIG. 16 shows a point 41 on the transfer material 25 when a toner having a higher viscosity than this toner is used. By increasing the viscosity of the toner, the spread of the toner during fixing is suppressed, The height of the toner after fixing increases. Thereby, Braille that is easy to identify is formed. Not limited to this viscosity, the height of the toner may be increased by changing other physical properties of the toner. Therefore, the developing device 13P for braille may contain toner suitable for braille, for example, toner having high viscosity.

Further, the toner in the cleaner box 24,
The toner remaining on the intermediate transfer belt 14 without being transferred to the transfer material 25 is collected, and the collected toner is used for the Braille developing device 1.
A toner circulator 51 for returning to 3P is provided. Since the Braille toner does not require a color and does not cause a problem of poor image quality related to the appearance, the toner collected by the toner collecting unit 51 can be reused, and the toner scatters. And no environmental pollution.

The mode selecting means may be provided in the color image forming apparatuses 1 and 2, or may be provided separately from the color image forming apparatuses 1 and 2, for example, in a controller for controlling a plurality of apparatuses. The invention includes any of them. Further, the present invention includes not only a full-color image forming apparatus but also a monochrome image forming apparatus and a mono-color image forming apparatus. Examples of the image forming apparatus include a copying machine, a facsimile, and a printer.

[0032]

As is apparent from the above description, according to the first aspect, when the Braille output mode is selected, the development is repeated a plurality of times, and the transfer and fixing are performed on the transfer material for each development. There is a configuration to perform. For this reason, there is an effect that the toner superimposed on the transfer material is securely held, and separation and scattering of the toner can be prevented.

Further, according to the second invention, as a developing device for the development, a developing device for the Braille output mode is provided in addition to the developing device for the normal output mode. Therefore, it is possible to adopt a toner suitable for Braille output regardless of whether the toner is suitable for normal output.

Further, according to the third aspect of the present invention, there is provided a configuration including a toner circulator for recovering residual toner generated in the process of forming the image and reusing the toner for the development.
For this reason, it is possible to further prevent the toner from being scattered and to reuse the toner, thereby contributing to the prevention of environmental pollution.

Further, according to the fourth aspect, the fixing strength at the time of selecting the Braille output mode is controlled so as to make the previous strength lower than that at the time of the final fixing. . For this reason, it is possible to prevent the toner from being excessively melted while preventing the detachment and scattering of the toner, and to reduce the number of repetitions of development, transfer and fixing.

According to the fifth to eighth aspects of the present invention, in the Braille output mode, the absolute value of the initial charging potential on the surface of the photosensitive member is reduced, or the absolute value of the developing bias is increased, or the exposure intensity is increased. Or to increase the relative speed between the developing device and the photosensitive member at the opposing portion thereof. For this reason, there is an effect that the control condition most suitable for the Braille output is easily obtained.

Further, according to the ninth aspect, the developing device dedicated to the Braille output mode is configured such that the toner viscosity of the developing device is larger than that of the other developing devices. For this reason,
It is possible to form a point where the convex shape is emphasized for Braille, and it is possible to form Braille that is easy to identify.

[Brief description of the drawings]

FIG. 1 is a view schematically showing a color image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a cross section of a point constituting Braille on a transfer material.

FIG. 3 is a plan view of a first toner image for forming the points shown in FIG. 2;

FIG. 4 is a plan view of the toner image in a state where a second toner image is superimposed on the toner image shown in FIG. 3;

FIG. 5 is a sectional view of the toner image shown in FIG. 4;

6 is a diagram illustrating an example of a fixing device in the color image forming apparatus illustrated in FIG.

FIG. 7 is a diagram illustrating a relationship between factors related to a toner height at a point formed on a transfer material.

FIG. 8 is a diagram showing a change in toner height when any one of the factors is changed based on the relationship shown in FIG. 7;

9 is a diagram illustrating a change in toner height when any one of the factors is changed based on the relationship illustrated in FIG. 7;

10 is a diagram showing a change in toner height when any one of the factors is changed based on the relationship shown in FIG. 7;

11 is a diagram showing a change in toner height when any one of the factors is changed based on the relationship shown in FIG. 7;

FIG. 12 is a diagram showing a state in which the density of the dots constituting the braille dots is controlled.

FIG. 13 is a diagram showing a state in which the area of the dots constituting the braille points is controlled.

FIG. 14 is a view schematically showing a color image forming apparatus according to a second embodiment of the present invention.

FIG. 15 is a diagram illustrating a cross section of a point on a transfer material when a normal output mode toner is used.

FIG. 16 is a diagram illustrating a cross section of a point on a transfer material when a high-viscosity toner for a Braille output mode is used.

[Explanation of symbols]

 2 Color Image Forming Apparatus 11 Exposure Device 12 Photoconductor 13Y, 13M, 13C, 13K, 13P Developing Device 14 Intermediate Transfer Belt 15 Paper Cassette 16 Fixing Device 16A Heating Roller 16B Pressure Roller 16C Solenoid 17 Discharge Unit 21 Charging Device 22 Rack Reference Signs List 24 Cleaner box 25 Transfer material 26 Guide member 27 Paper passage 28 Timing roller 29 Transfer roller 31 Path switching means 32 Paper discharge port 33 Guide member 34 Return path 35 Intermediate roller 51 Toner circulator

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) G03G 15/20 G03G 15/08 507D 2H077 15/22 103 21/00 326 2H078 21/10 (72) Inventor Shigetaka Yoshida Osaka International Building Minolta Co., Ltd. (72) Inventor Tamotsu Sakuraba 2-3-1-13 Azuchicho, Chuo-ku, Osaka City, Osaka City Osaka International Building Minolta Co., Ltd. 72) Inventor Yoshiki Nakane 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka Inside Osaka International Building Minolta Co., Ltd. (72) Inventor Koichi Eto 2-3-13-Azuchicho, Chuo-ku, Osaka-shi, Osaka Osaka International Building Minolta Co., Ltd. (72) Inventor Takashi Akazawa 2-3-13 Azuchicho, Chuo-ku, Osaka-shi, Osaka F-term in Osaka International Building Minolta Co., Ltd. (reference) 2C055 BB00 BB05 2H027 DA02 DA04 DA06 DA07 DA17 DA41 DD05 EA01 EA02 EA03 EA05 ED02 ED03 ED06 ED09 ED24 E D25 EE03 FA30 FA35 2H033 AA41 AA48 BB34 CA39 2H034 CA01 CB01 2H076 AB02 DA01 DA21 DA36 2H077 AA37 AC16 AD02 AD35 BA03 BA10 DB08 EA24 GA13 GA15 2H078 AA34 AA40 BB01 DD21 DD38 DD51 DD56 EE40

Claims (9)

[Claims] 1. Through development, transfer, and fixing processes,
An image forming device for forming an image on a transfer material, in addition to the normal output mode, in an image forming apparatus operably formed in the Braille output mode, when the Braille output mode is selected,
An image forming apparatus, wherein the development is repeated a plurality of times, and the transfer and fixing are performed on the transfer material for each development. 2. The image forming apparatus according to claim 1, wherein a developing device for the Braille output mode is provided as the developing device for the development, in addition to the developing device for the normal output mode. apparatus. 3. The image forming apparatus according to claim 1, further comprising a toner circulator that collects residual toner generated in a process of forming the image and reuses the toner for the development. 4. The fixing device according to claim 1, wherein the fixing intensity when the Braille output mode is selected is controlled so as to make the intensity before the final fixing lower. The image forming apparatus according to any one of the above. 5. The method according to claim 1, wherein an absolute value of an initial charging potential of the surface of the photoreceptor to be exposed is reduced during the operation in the Braille output mode as compared with the normal output mode. The image forming apparatus according to claim 1, wherein: 6. The method according to claim 1, wherein an absolute value of a developing bias used for the developing is set higher during the operation in the Braille output mode than in the normal output mode. An image forming apparatus according to any one of the above. 7. An exposure apparatus for exposing the surface of a photoreceptor for exposure for development, wherein the exposure intensity is higher when operating in the Braille output mode than in the normal output mode. The image forming apparatus according to claim 1, wherein: 8. A relative speed between the developing device and a portion opposed to a photoreceptor developed by the developing device when the device is operated in the Braille output mode as compared with the normal output mode. The image forming apparatus according to claim 1, wherein: 9. The image forming apparatus according to claim 2, wherein a toner viscosity of a developing device dedicated to the Braille output mode is larger than a toner viscosity of another developing device.