JP2912258B2 - Back exposure recording image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a back exposure recording image forming apparatus, and more particularly, to a method for forming a color toner image on a belt photoreceptor by electrophotography and transferring the toner image onto a transfer paper to obtain an image. To a rear-exposed recording image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, this type of back-exposed recording image forming apparatus, as shown in, for example, Japanese Patent Application Laid-Open No. 5-323775, exposes the back surface of a belt photoreceptor by an electrophotographic method, and develops the image by a developing device. A color toner image is formed on a belt-shaped image forming body, and the toner image is transferred onto a transfer paper to obtain an image.

FIG. 7 shows an image forming system in which a color image is formed by one rotation of the belt photoreceptor 1, that is, by a one-pass system.
And the laser writing system unit 7 for the developing device 9, the charging device 61B and the laser writing system unit 7A for the developing device 10, the charging device 61C and the laser writing system unit 7B for the developing device 10, and the charging device 61D and the laser for the developing device 11. The writing unit 7C is provided as a dedicated set, and charging, exposure, and development are all completed as the belt photoconductor 1 advances.
After the photosensitive layer of the belt photoreceptor 1 enters the charger 61A, charging, exposure and development are sequentially repeated to form a color image on the photosensitive layer of the belt photoreceptor 1 in one process. Paper feed roller 3
After the transfer paper P fed at 0 is adjusted in position by the timing roller 32, the color image is transferred by the transfer device 12. After the transfer of the color image, the recording paper P is sent to a fixing roller 34 to be fixed, and then discharged outside by a discharge roller 35. The photosensitive layer of the belt photoreceptor 1 is cleaned by the blade 13A of the cleaning device 13 to prepare for the next image formation.

[0004]

A first problem of the above-described conventional back-exposure recording image forming apparatus is that the apparatus is increased in size and cost. The reason is that a laser writing system unit, which is relatively expensive and large as an optical system component, is required.
This is because it is installed around the table and the belt photoconductor.

[0005] The second problem is that it is difficult to make color overlay and print quality uniform and stable. The reason is that the means for keeping the gap between the surface of the belt photoreceptor and the developing unit constant is not clear, so that it is not possible to superimpose the colors in one pass or to make the density of each color uniform. Further, since there is no member for regulating the belt running on the opposing surface of the charger, it is difficult to keep the charging potential uniform. Also, there is no member that regulates belt running on the surface facing the portion where the bright line is formed by the optical system. In the above technology, it is specified that, besides the laser writing optical system, an optical system in which a light emitting section and a convergent light transmitting body are integrated can also be used. However, when the above configuration is used, the exposure energy amount becomes uniform. This is because it becomes difficult.

An object of the present invention is to provide a back-exposure recording image forming apparatus having a high multi-color printing speed by forming an image by a one-pass method in multi-color printing in the same manner as in single-color printing. By keeping the gap between the charged part and the photosensitive body, the distance between the writing system and the photosensitive body, and the gap length between the photosensitive body and the developer layer uniform by bringing the photosensitive body into close contact, the density is more uniform. It is an object of the present invention to provide a back exposure recording image forming apparatus having stable printing quality.

[0007]

A back-exposure recording image forming apparatus according to the present invention comprises an endless belt photosensitive member having a photosensitive layer provided on a conductive substrate, and a plurality of types of belt photosensitive members formed on the belt photosensitive member. An image forming apparatus having a charging unit for forming an electrostatic latent image of a plurality of types and a plurality of developing units for developing the electrostatic latent image and forming a plurality of toner images on the belt photoconductor in a superimposed manner. A conductive substrate of the belt photoreceptor is a light-transmitting conductive substrate, and an image exposure for forming at least one of the plurality of types of electrostatic latent images is performed by using a light emitting element array as a light source.
And exposure performed through the light-transmitting conductive substrate.
Means, and at least the entire surface of the exposed area is
The belt photoreceptor is run while the
The charging means from the belt photoreceptor.
The mechanical distance condition between the exposure unit and the developing unit is always
Cover glass attached to the charging means in order to keep it constant
And

[0008]

Further, a back-exposure recording image forming apparatus of the present invention includes the above-mentioned exposure means using a light emitting diode array or a laser diode array as a light source.

Further, the back-exposure recording image forming apparatus of the present invention is provided with the exposing means which uses a self-focusing type optical fiber array or an optical fiber array as a means for forming the light emitting element array image on the belt photoreceptor.

Further, in the back exposure recording image forming apparatus of the present invention, the self-focusing type optical fiber array or the optical fiber array embedded in the cover glass may be used as a means for forming the light emitting element array image on the belt photoreceptor. The exposure means to be used is provided.

[0012]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. Referring to FIG. 1, a belt photoreceptor 1 serving as a belt-shaped image forming body includes a driving roller 2 and driven rollers 3 and 44.
And is suspended between the tension roller 19 and conveyed clockwise. As shown in FIG. 1B, a transparent base 1 a is used for the belt photoreceptor 1.
a is coated with a photosensitive layer 1b. The transparent base 1a of the substrate is made of a polyester material, and the photosensitive layer 1b is composed of a photosensitive layer including a transparent conductive layer, a blocking layer, a charge generation layer, and a charge transport layer.

The LED writing unit 22 is fixed to the belt unit 14 so as to be inscribed on the right side of the belt photoconductor 1, and has an advantage of being a guide member for the belt photoconductor 1. The driven roller 24 makes an angle to the belt photoreceptor 1 and
This enables the ED writing system unit 22 to uniformly adhere to the belt photoconductor 1.

Scorotron chargers 61A, 61B, 61
C and 61D are charging means. Developing device 8 as developing means
Numeral 11 contains developers of different colors, for example, developers containing yellow, magenta, cyan, and black toners, respectively. Chargers 61A, 61B, 61C, 6
1D and developing units 8 to 11 are LED writing unit 22
Are disposed facing the inscribed belt photoreceptor 1 and are fixed to the image forming apparatus main body 15. Each of the developing units 8 to 11 is provided with a developing sleeve 8A, 9A, 10A, 11A which keeps a predetermined gap from the photosensitive layer 1b of the belt photosensitive member 1. A fixed amount of developer is adhered to the developing sleeves 8A, 9A, 10A, and 11A.
It has a function of adhering toner by a non-contact developing method to apply a superimposed voltage of alternating current to visualize the image.

The belt unit 14 includes a neutralizing lamp 2
It has 5,43,45. The blade 13A is kept at a position away from the surface of the photosensitive layer 1b during image formation, and is brought into pressure contact with the surface of the photosensitive layer 1b as shown in the drawing only during cleaning after image transfer.

The color image forming apparatus of this embodiment is
A belt photoreceptor 1 suspended from a driving roller 2, driven rollers 3, 44 and a tension roller 19;
The ED writing unit 22 is configured as an integral belt unit 14 as shown in FIG. 1, and is fixed to the image forming apparatus main body 15 with screws or the like.

FIG. 2 is a diagram showing a detailed configuration of the LED writing unit 22 in FIG. Referring to FIG.
The LED writing unit 22 includes an LED light emitting unit 22.
A, 22B, 22C, 22D and selfoc (self-focusing optical fiber) lens arrays 22E, 22F, 22
G, 22H are installed perpendicular to the surfaces of the cover glasses 22I, 22J. Cover glass 22I, 22
The corners of the J surface are rounded and chamfered.
The belt photoreceptor 1 includes a driving roller 2 and driven rollers 3, 24.
Further, it is suspended by running while being in close contact with the entire surfaces of the cover glasses 22I and 22J, the gap length between the grids 62A, 62B, 62C and 62D of the chargers and the belt photoreceptor 1, the selfoc lens arrays 22E and 22.
F, 22G, 22H and the belt photosensitive member 1 and the developing sleeves 8A, 9A, 10A, 11A and the belt photosensitive member 1 are fixed.

Next, the operation of this embodiment will be described with reference to FIG. FIG. 1 shows a configuration in which a color image is formed by one rotation of the belt photoreceptor 1, that is, by a one-pass method. The photosensitive layer 1b of the belt photoreceptor 1 first has a charger 61A.
, And sequentially repeats charging, exposure and development four times to form a toner image on the photosensitive layer 1b of the belt photosensitive member 1 in one process. The recording paper P supplied from the paper supply tray 26 or the paper supply cassette 29 is adjusted in position by the timing roller 32, and then a toner image as a color image is transferred by applying a voltage from the transfer roller 27. After the transfer of the color image, the recording paper P is sent to a fixing roller 34 for fixing, and then discharged to the upper portion of the main body by a discharge roller 35. The photosensitive layer 1b of the belt photoreceptor 1 is cleaned by the blade 13A of the cleaning device 13 to prepare for the next image formation.

Next, this embodiment will be described in more detail with reference to FIG. Referring to FIG. 2, the belt photoreceptor 1 has a transparent base 1a made of polyethylene terephthalate having a thickness of 65 μm, a transparent conductive layer, a blocking layer,
This is a seamless belt composed of a photosensitive layer 1b having a total thickness of 25 μm including a charge generation layer and a charge transport layer. An LED writing unit 22 having cover glasses 22I and 22J having a thickness of 2 mm, all corners of which are chamfered by C0.5, is installed on the inner peripheral portion of the belt photoconductor 1, and the belt photoconductor 1 is covered with the cover glass 22I. , 22J while being in close contact with the entire surface.

Next, the operation of this embodiment will be described in detail with reference to FIGS. 2, 4, 5, and 6. FIG.
, Charging devices 61A, 61B, 61C, 61D
-800 on grids 62A, 62B, 62C, 62D of
A voltage of V is applied to charge the surface of the photosensitive layer 1b. At this time, the gap length between the grids 62A, 62B, 62C, 62D and the photosensitive layer 1b must keep a certain distance.
Referring to FIG. 4, the larger the gap length, the lower the charging efficiency. Also, if the gap is too small, contact may cause problems such as destruction of the photosensitive layer and scraping of the toner image, and it is desirable that the gap length always be kept around 2.0 mm even when the belt photoreceptor 1 is running. Therefore, a configuration as shown in FIG. 2 is required.

The distance between the selfoc lens arrays 22E, 22F, 22G, 22H of the LED writing unit 22 and the photosensitive layer 1b must be kept constant.
Referring to FIG. 5, the LED spot diameter changes whether the distance between the SELFOC lens array and the photosensitive layer is too short or too long. As a result, the amount of energy per fixed area and the resolution vary. In this embodiment, the distance between the SELFOC lens array and the photosensitive layer is set to 5.0 mm, and LE
When the focal depth of D is set to ± 0.1 mm, the distance between the SELFOC lens array and the photosensitive layer must always be kept at 5.0 ± 0.1 mm even when the belt photoconductor 1 is running.
Therefore, a configuration as shown in FIG. 2 is required.

Developing sleeves 8A, 9A, 10A, 11A
And the photosensitive layer 1b must keep a constant distance. As shown in JP-A-63-210874, when the length of the gap between the photosensitive member and the developer layer is increased, the flying amount of the toner is sharply reduced (see FIG. 6). However, in this embodiment, in order to realize toner image superposition in one pass, the photoconductor and the developer layer must not be in contact with each other, and a certain distance must be maintained. In this embodiment, assuming that the thickness of the developer layer on the sleeve is 0.25 to 0.35 mm, the distance between the sleeve and the photosensitive layer is always 0.1 mm as shown in FIG. It is desirable to keep it around 5 mm. Therefore, a configuration as shown in FIG. 2 is required.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 illustrates a second embodiment of a part of FIG. Referring to FIG. 3, a cover glass 22I in which a fiber array 22K is embedded is used without using the selfoc lens array in FIG.
Is run while being in close contact with the entire surface of the cover glass 22I, it is possible to further reduce the size of the apparatus and to achieve higher printing resolution than in the above-described embodiment.

In the above embodiment, the combination of the LED and the SELFOC lens array is used as the exposure means using the light emitting element array as a light source, but not only this combination but also a laser diode array or a cell instead of the LED. An optical fiber array or the like can be used instead of the Fock lens array.

The image forming apparatus of the present invention includes four sets of a charging unit, an exposing unit, and a developing unit. Furthermore, each developing unit is not in contact with the surface of the belt photoreceptor. For this reason, the toner image can be superimposed on the belt photoreceptor, and multicolor printing can be performed in the same time as the single color printing. Further, by defining the running position of the belt photoconductor on the entire surface of the cover glass of the LED writing unit, the gap length between the grid and the belt photoconductor is stabilized, and the surface potential of the belt photoconductor is stabilized. Also, the spot diameter of the LED is stable,
The surface potential and the resolution of the belt photoreceptor after exposure are stabilized.
Further, the gap length between the belt photoreceptor and the developer layer on the sleeve is stabilized, and the development amount is stabilized.

[0027]

The first effect is that small, inexpensive and high-speed multicolor printing can be performed. The reason is that multiple L
This is because an LED writing unit including an ED array is used.

The second effect is that uniform density and uniform printing quality can be obtained with a simple structure. The reason for this is that the belt photosensitive member is run while being brought into close contact with the entire surface of the cover glass of the LED writing unit, so that the mechanical distance condition of each process can always be kept constant.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a configuration diagram showing details of an LED writing unit unit of the embodiment.

FIG. 3 is a configuration diagram showing details of an LED writing unit unit according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a relationship between a gap length between a grid and a photosensitive layer of the present invention and charging efficiency.

FIG. 5 is an explanatory diagram showing a relationship between a distance between a selfoc lens array of the present invention and a photosensitive layer and an LED spot diameter.

FIG. 6 is an explanatory diagram illustrating a relationship between a distance between a sleeve and a photosensitive layer according to the present invention and a toner flying amount.

FIG. 7 is a configuration diagram illustrating a conventional image forming apparatus.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 belt photoreceptor 1 a transparent base 1 b photosensitive layer 2 drive roller 3, 24, 41, 44 driven roller 8, 9, 10, 11 developer 8 A, 9 A, 10 A, 11 A sleeve 13 cleaning device 14 belt unit 15 image forming device body 22 LED Writing System Units 22A, 22B, 22C, 22D LED Light Emitting Units 22E, 22F, 22G, 22H Selfoc Lens Array 22I, 22J Cover Glass 26 Paper Feed Tray 27 Transfer Roller 29 Paper Feed Cassette 34 Fixing Roller 61A, 61B, 61C , 61D Charger 62A, 62B, 62C, 62D Grid

Continuation of the front page (56) References JP-A-3-259271 (JP, A) JP-A-3-144592 (JP, A) JP-A-3-144528 (JP, A) JP-A-8-334973 (JP) JP-A-8-62921 (JP, A) JP-A-4-9059 (JP, U) JP-A-61-44657 (JP, U) JP-A-4-137376 (JP, U) (58) Surveyed fields (Int.Cl. ⁶ , DB name) G03G 13/01 G03G 15/01-15/01 117 G03G 15/04-15/056

Claims (4)

(57) [Claims] 1. An endless belt photoreceptor having a photosensitive layer provided on a conductive substrate, charging means for forming a plurality of types of electrostatic latent images formed on the belt photoreceptor, In an image forming apparatus having a plurality of developing means for developing a latent image and forming a plurality of toner images on the belt photoconductor in a superimposed manner, the conductive substrate of the belt photoconductor is formed of a light-transmitting conductive material. A substrate, wherein the image exposure for forming at least one of the plurality of types of electrostatic latent images is performed by using a light emitting element array as a light source;
And exposure performed through the light-transmitting conductive substrate.
Means, and at least the entire surface of the exposed area is
The belt photoreceptor is run while the photoreceptor is in close contact with the inside of the photoreceptor.
The charging means from the belt photoreceptor.
The mechanical distance condition between the exposure unit and the developing unit is always
Cover glass attached to the exposure means in order to keep it constant
Back exposure recording image forming apparatus characterized by comprising a scan. 2. A back-exposure recording image forming apparatus according to claim 1, further comprising said exposure means using a light emitting diode array or a laser diode array as a light source. 3. The exposure device according to claim 1, further comprising a self-focusing type optical fiber array or an exposure unit using an optical fiber array as a unit for forming the light emitting element array image on the belt photoreceptor. Back exposure recording image forming apparatus. 4. A characterized in that it comprises the exposure means using the retro-reflective optical fiber array or the optical fiber array is embedded in the cover glass as a means for imaging the light emitting element array image on the photoreceptor belt The back exposure recording image forming apparatus according to claim 1.