JPH08185019A - Image forming device - Google Patents

Abstract

PURPOSE: To reduce cost by shortening the length in a main scanning direction of a line type exposure means for writing a one-point image such as the impression of the seal of approval or a confidential mark. CONSTITUTION: The line type exposure means 12 fixed within a write range shorter than the deflecting, scanning and exposing width of a deflecting scanning type exposure means on a photoreceptor 3 is fixedly arranged at a different position from the beam irradiating position of the deflecting and scanning type exposure means opposite the irradiating position on the outer periphery of the photoreceptor, and the one-point image of a second color such as the impression of the seal of approval or the confidential expression is formed by using the exposure means 12 whose write range is short.

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 such as a digital copying machine, a facsimile, a printer or the like, which forms an image of two colors according to an electrophotographic process.

[0002]

2. Description of the Related Art Generally, an image forming apparatus for forming an image by an electrophotographic process is equipped with a deflection scanning type exposure means for deflecting and scanning with a polygon mirror using a laser light source or the like. Recently, there is a demand for a model that is inexpensive and capable of two-color printing. In the case of two-color printing, unlike full-color printing, the necessary information depends on black printing, and in order to perform a one-point display such as a seal such as a seal or confidential display, a color other than black (for example, red) is used. It is printed. Since the printing of the second color does not expect an accurate image, the electrostatic latent image of the first color is written on the photoconductor by the deflection scanning type exposure means, and the line type exposure means is relatively small and inexpensive. There is an image forming apparatus which forms an electrostatic latent image of the second color on a photoconductor by means of. An example of such an image forming apparatus is disclosed in Japanese Patent Application Laid-Open No. 5-309877.

[0003]

SUMMARY OF THE INVENTION In a conventional image forming apparatus capable of two-color printing, which uses both a deflection scanning type exposure means and a line type exposure means, the deflection scanning exposure means has a deflection scanning exposure on a photosensitive member. A long line type exposure means having a writing range equivalent to the width is used. Such a line type exposure means is mainly intended to perform a one-point display such as a seal or a confidential display such as a stamp,
The display location of such a display is often determined by the format. For this reason, the entire area of the line type exposure means is rarely used, and the part that is frequently used is a small part. Even in the case of the line type exposure means, the cost becomes extremely high as the total length becomes long, and the user is burdened.

[0004]

According to the first aspect of the present invention,
A rotatable photoconductor, a charging unit arranged opposite to the outer periphery of the photoconductor, a deflection scanning type exposure unit for deflecting and scanning the beam light emitted from a light emitting source toward the photoconductor, and the deflection scanning type exposure unit. First developing means for developing the electrostatic latent image formed on the outer peripheral surface of the photoconductor by means, and a writing range shorter than the deflection scanning exposure width of the deflection scanning type exposure means on the photoreceptor. A line type exposure unit fixedly arranged at a position different from the beam irradiation position of the deflection scanning type exposure unit on the outer periphery of the photoconductor, and the line type exposure unit formed on the outer peripheral surface of the photoconductor. The image forming apparatus includes a second developing unit that develops an electrostatic latent image.

According to a second aspect of the present invention, in the first aspect of the invention, one side edge of the transfer paper of each size conveyed toward the photoconductor with one side edge as a reference, and writing by the line type exposure means are used. The image forming apparatus has one end on the reference side substantially aligned with the other.

According to a third aspect of the present invention, in the first aspect of the present invention, the writing range of the line type exposure means is set to approximately one half of the deflection scanning exposure width of the deflection scanning type exposure means, and exposure is performed with the center as a reference. In the image forming apparatus, the center of the transfer paper of each size conveyed toward the body in the paper width direction and the one end of the line-type exposure means on the writing reference side are substantially aligned with each other.

[0007]

According to the invention described in claim 1, it is possible to form a one-point second color image such as a seal stamp such as a seal or confidential display using the line type exposure means having a short writing range. .

According to the second aspect of the present invention, it is possible to form a one-point image on one side of each transfer sheet even if the transfer sheets have different sizes.

According to the third aspect of the present invention, even if the size of the transfer paper is different, a one-point image can be formed closer to one side than the center of each transfer paper in the paper width direction.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. FIG. 4 shows two colors (black / red) used as an example of the present invention.
1 shows an outline of a digital copying machine for printing. A document reading device 2 equipped with an automatic document feeder (hereinafter referred to as ADF) 1 is arranged on the upper part of the copying machine main body.
An electrophotographic printer unit 4 centering on a drum-shaped photosensitive member 3 is provided in the main body of the copying machine, which is located below the document reading device 2.

The original reading device 2 exposes and scans the original conveyed and set on the contact glass 5 by the ADF 1 with an exposure lamp 6, and reflects the reflected light by a mirror / lens optical system 7 such as a CCD image sensor. By forming an image on 8, the image is read as an electric signal.

That is, when the copy button is depressed after the copy data such as the number of copies is input by operating the ten-key pad of the operation unit (not shown), the original set on the contact glass 5 is exposed and scanned. The reading operation is started. In this case, the originals are set directly on the contact glass 5, or the originals stacked on the ADF 1 are conveyed one by one and set on the contact glass 5. At the time of this reading, the solid-state image pickup device 8 separates the original image into black / red and converts it into an electric signal which becomes image information of each color.
The image information of each color read by the document reading device 2 is output to the printer unit 4 after undergoing necessary image processing in the image processing unit.

In the printer section 4, around the photosensitive member 3, a charging charger 9 as a charging means, a first exposure device 10 as a deflection scanning type exposure means, and a first developing means using black toner are provided. Developing device 11, a second exposing device 12 serving as a line type exposing means, a developing device 13 serving as a second developing means using red toner, a transfer charger 14, and a cleaning device 15 in order. It is arranged. That is, the first exposure device 10 and the second exposure device 12 are arranged so as to form latent images at different positions on the outer peripheral surface of the photoconductor 3, and the black read by the document reading device 2 side. / Among the red image information, the red image information is temporarily stored in the memory and then output to the second exposure device 12 at a timing slightly delayed from the black image information.

The electrostatic latent image formed on the photoconductor 3 by the first exposure device 10 after the outer peripheral surface of the photoconductor 3 is uniformly charged by the charger 9 is the first developing device 11.
To visualize with black toner. The electrostatic latent image formed on the photoconductor 3 by the second exposure device 12 is visualized by the second developing device 13 with red toner. Then, the transfer paper 18 fed from the paper feed tray 16 or the like by the paper feed roller 17 is temporarily stopped by the registration roller 19, and then the registration roller 18 is timed so as to match the leading edge of the toner image on the photoconductor 3. It is conveyed by 19 to the transfer portion by the transfer charger 14. The transfer paper 18 is transferred by the transfer belt 20 in the transfer section. The transfer paper 18 onto which the toner image on the photoconductor 3 has been transferred is the conveyor belt 2
The sheet is conveyed to the fixing device 21 side by 0, undergoes a fixing process, and is appropriately discharged or re-conveyed and fed. In this way, a black / red two-color image is formed.

Here, the structure of the first exposure apparatus 10
The operation will be described in detail with reference to FIG. The first exposure apparatus 10 uses a semiconductor laser 22 as a light emitting source, and a laser unit 24 in which the semiconductor laser 22 and a collimator lens 23 are integrally assembled, and a cylindrical lens 25 having a curvature in the sub-scanning direction. And polygon motor 2
A polygon mirror 27 rotated at a high speed by 6, an fθ lens 28, and a reflection mirror 29 are housed in an optical case 30. In this optical case 30,
A dustproof glass 31 for closing an opening (not shown) for emitting a beam of light is attached to the photoconductor 3 side. The optical case 30 is sealed by an upper cover (not shown) attached to the upper surface of the optical case 30 in order to prevent invasion of floating substances such as toner. The laser unit 24 is structured to be attached from the outside of the optical case 30.

As a result, the beam light emitted from the semiconductor laser 22 and modulated by the image information for black is converted into a parallel beam by the collimator lens 23, and thereafter,
The light is sequentially incident on the respective reflecting surfaces of the polygon mirror 27 which is rotating at a high speed via the cylindrical lens 25, and is reflected by these reflecting surfaces, so that the photoconductor 3 is deflected and scanned in the main scanning direction. At this time, by passing through the fθ lens 28, the fθ characteristic is corrected so that the image forming point on the photoconductor 3 moves at a constant speed on a straight line parallel to the photoconductor axis, and the reflection mirror 2
It is deflected toward the photoconductor 3 side by 9. Since the photoconductor 3 itself rotates in the sub-scanning direction in parallel with the main scanning by the first exposure device 10, a two-dimensional latent image is formed.

Both ends of the deflection range of the polygon mirror 27 are not used for the above-mentioned optical writing, and a part of the beam light of this part is passed through the mirror 32 and the synchronization detection sensor 3 is used.
3 and is used to obtain a synchronizing signal for aligning the main scanning exposure start position.

Next, the structure and operation of the second exposure device 12 will be described with reference to FIG. This second exposure apparatus 1
2 is configured by mounting a substrate 36 holding the LED array chip 34 and the IC drive circuit 35, and a rod lens array 37 facing the LED array chip 34 in a housing 38. The LED array chip 34 is formed by arranging LEDs forming a large number of minute light emitting portions along the main scanning (axial direction) of the photoconductor 3.

In this case, the image of the second color formed by the second exposure device 12 is a one-point image such as a stamp such as a stamp or confidential display as described above, and the main scanning of these images is performed. Since the length in the direction is short, the second exposure apparatus 1
The writing range of 2, that is, the LED array width is set to a value of about 100 mm, which is shorter than the deflection scanning exposure width on the photoconductor 3 of the first exposure unit 10. Along with this, the entire length of the second exposure device 12 including the rod lens array 37 and the housing 38 is also shortened.

As shown in FIG. 6, the second exposure device 12
Are transfer sheets S1 and S of respective sizes (A3, B4, A4, B5) that are conveyed toward the photoconductor 3 with one side edge as a reference.
It is fixedly provided so that one side edge of S2, S3, S4 and one end on the writing reference side substantially coincide with each other. As a result, on the transfer sheets S1, S2, S3, and S4 of each size, a one-point image such as a seal such as a stamp or a confidential display is formed within a 100 mm width area indicated by diagonal lines.
In the case of the A3 size transfer sheet S1 having the maximum width of 297 mm, it is possible to form a one-point image in a region of at least one-third from one edge serving as the reference edge.

Further, as shown in FIG. 7, when the transfer sheets S1, S2, S3 and S4 of each size are conveyed with the center as a reference, the writing range of the second exposure device 12 is set to the first exposure device 10. Approximately one half of the deflection scanning exposure width of 150 mm
The transfer paper S1, S2, S3, S4 of the respective sizes are substantially aligned with the center of the transfer paper S1 in the paper width direction and one end of the second exposure device 12 on the writing reference side.
Regardless of the size of S2, S3, and S4, it is possible to form a one-point image in the one-half half area indicated by diagonal lines.

The LED is connected to the IC drive circuit 35 by wire bonding. Further, since the LED array chip 34 and the IC drive circuit 35 are housed in the housing 38 having a hermetically-sealed structure, contamination by toner or the like is prevented.

Next, the two colors (black / black) used in this embodiment are shown in FIG.
The electrical system structure of the digital copying machine for red) is shown and its operation is described in detail. The document reading unit 39, the image processing unit 40, and the printer unit 4 of the document reading device 2 are sequentially connected and also connected to the system controller 41 via a bus line. The system controller 41 includes a document reading unit 39 and a printer unit 4.
A start signal, a sync signal, and a magnification designation signal are sent to the
The entire system is controlled by operating status signals such as t, ready, busy, stop, etc.

The operation unit 42 connected to the system controller 41 is, as shown in FIG. 6, a liquid crystal display 43 as a means for indicating an operation mode and the like, and a plurality of inputs by a ten-key pad or a touch panel for inputting operation information. And inputting operation information such as the number of prints, the magnification, and the print start, which are input from the input unit 44, to the system controller 41. Further, the display content of the liquid crystal display 43 is the same as the system controller
It is switched by the information from 1.

R (red) that passes light corresponding to image information obtained by scanning an original at the scanning speed corresponding to the magnification specified by the print start signal sent from the system controller 41 is passed through the original reading section 39. , G (green),
B (blue) filters 45R, 45G, and 45B, and three solid-state image pickup devices (CCD image sensor) 8 that convert light incident through these filters 45R, 45G, and 45B into electric signals are provided. . 3 provided on the output side of the solid-state image sensor 8 for each color of R, G, B
A number of A / D converters 46 are connected, and a shading correction circuit 47 and a buffer memory 48 are sequentially connected to the output side of these A / D converters 46. In this configuration, the image information read by the solid-state image pickup device 8 is converted into digital image data by the A / D converter 46, and is temporarily stored in the buffer memory 48 after shading correction. The buffer memory 48 outputs the synchronized image data of each color to the image processing unit 40 in the next stage.

The image processing section 40 includes a document reading section 39.
A .gamma. Correction circuit 49 is provided for changing the gradation of the image data sent from the device in accordance with the characteristics of the photoconductor 3 and the first and second developing devices 11 and 13. This γ correction circuit 4
9 is the information from the system controller 41,
3 of "black mode", "red mode" and "black / red mode"
The correction process switches in each of the two modes. The output data of the γ correction circuit 49 is sent to the black separation / color generation circuit 50. The black separation / color generation circuit 50, in accordance with the information from the system controller 41 (three mode information described above), writes the black image data written by the first exposure apparatus 10 and the red image data written by the second exposure apparatus 12. And are generated and output to the gradation processing circuit 51. Gradation processing circuit 51
Performs gradation correction processing according to the characteristics of the first and second developing devices 11 and 13 based on the information from the system controller 41.

The information of the system controller 41 here includes, for example, "character mode", "photo mode", "character / photo mode", "magnification" as the image processing mode. The video data output from the gradation processing circuit 51 is temporarily stored in the frame memory 52.
The memory control circuit 53 is connected to the frame memory 52 and the ROM 54.
54, image data is read out, and black image data is output to the printer unit 4, and red image data is output to the printer unit 4 via the buffer memory 55. The first exposure device 10 is driven by the laser driver 56 to write black image data on the photoconductor 3, and the second exposure device 12 is LE.
The red image data is written to the photoconductor 3 by being driven by the D array driver 57. In this case, the buffer memory 55
In order to delay the output of the red image data by the interval between the writing positions of the first and second exposure devices 10 and 12, the red image data is temporarily stored and then output to the printer unit 4 at a timing.

Further, in the ROM 54, one-point image data such as a seal such as a seal stamp, confidentiality or the like, and image data such as a mesh pattern are coded and stored. In this case, the memory control circuit 53 adds the image data of the ROM 54 to the image data read from the frame memory 52 based on the information from the system controller 41, or mirrors the image data of the frame memory 52, italicizes, shades, and doubles it. It is possible to perform processing such as copying and rotation, and change the timing of reading image data.

In the printer unit 4, the laser driver 5
6 drives the first exposure device 10 based on the black image data sent from the image processing unit 40, and writes an electrostatic latent image developed with black toner on the outer periphery of the photoconductor 3. LE
The D array driver 57 drives the second exposure device 12 based on the red image data sent from the image processing section 40, and writes an electrostatic latent image developed with red toner on the outer periphery of the photoconductor 3. . At this time, the laser driver 56 and the LE
The D array driver 57 is the system controller 41.
Based on the information from the first and second exposure apparatuses 10 and 12
Change the driving method of. That is, the first exposure apparatus 1
In the case of 0, one-dot multi-value writing is performed because one dot is formed by a plurality of beam spots, and the second exposure apparatus 1
In the case of 2, one dot is formed by one spot, and therefore one dot binary writing is performed.

[0030]

According to the first aspect of the invention, the line type exposure means defined in the writing range shorter than the deflection scanning exposure width on the photoconductor of the deflection scanning type exposure means is provided with the line type exposure means on the outer periphery of the photoconductor. Since it is fixedly opposed to a position different from the beam irradiation position of the scanning type exposure means, a line type exposure means having a short writing range is used to provide a one-point image of a second color such as a stamp such as a seal or confidential display. Can be formed. Further, since the line type exposure means has a short writing range, the cost can be reduced.

According to a second aspect of the invention, in the first aspect of the invention, one side edge of the transfer paper of each size conveyed toward the photoconductor with one side edge as a reference, and writing by the line type exposure means. Since one end on the reference side is made to substantially coincide with each other, a one-point image can be formed on one side of each transfer paper even if the size of the transfer paper is different.

According to a third aspect of the present invention, in the first aspect of the invention, the writing range of the line type exposure means is set to be approximately one half of the deflection scanning exposure width of the deflection scanning type exposure means, and the center reference is used for exposure. Since the center of the transfer paper of each size conveyed toward the body in the paper width direction and the one end of the line type exposure means on the writing reference side are substantially aligned with each other, even if the transfer paper size is different, one point It is possible to form a specific image on one side of the center of each transfer sheet in the paper width direction.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing a line type exposure unit according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a deflection scanning type exposure means.

FIG. 3 is a vertical sectional front view showing a digital copying machine for two-color printing.

FIG. 4 is a block diagram showing an electrical system of the digital copying machine.

FIG. 5 is a plan view of an operation unit.

FIG. 6 is a plan view showing the relationship between the transfer paper and the line type exposure means.

FIG. 7 is a plan view showing the relationship between the transfer paper and the line type exposure means.

[Explanation of symbols]

 3 Photoconductor 9 Charging Means 10 Deflection Scanning Exposure Means 11 First Developing Means 12 Line Exposure Means 13 Second Developing Means S1 to S4 Transfer Paper

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomoyuki Yoshida 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Inventor Shigeru Watanabe 1-3-6 Nakamagome, Ota-ku, Tokyo Stocks Within Ricoh Company (72) Inventor Shinji Kobayashi 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Company, Ltd.

Claims (3)

[Claims] 1. A rotatable photoconductor, a charging unit arranged to face the outer periphery of the photoconductor, a deflection scanning type exposure unit for deflecting and scanning a beam of light emitted from a light source toward the photoconductor. First developing means for developing the electrostatic latent image formed on the outer peripheral surface of the photoconductor by the deflection scanning type exposure means, and writing shorter than the deflection scanning exposure width on the photoconductor of the deflection scanning type exposure means. A line type exposure unit fixedly opposed to a beam irradiation position of the deflection scanning type exposure unit on the outer periphery of the photoconductor defined in a range, and the outer periphery of the photoconductor by the line type exposure unit. An image forming apparatus comprising: a second developing unit for developing the electrostatic latent image formed on the surface. 2. The one side edge of the transfer paper of each size conveyed toward the photoconductor with the one side edge as a reference and one end of the line type exposure means on the writing reference side are substantially aligned with each other. The image forming apparatus according to claim 1. 3. The writing range of the line type exposure means is defined to be approximately one half of the deflection scanning exposure width of the deflection scanning type exposure means,
2. The center of the transfer paper of each size conveyed toward the photoconductor on the basis of the center in the paper width direction and one end of the line type exposure means on the writing reference side are substantially aligned with each other. Image forming device.