JPH1086438A - Image-forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image-forming apparatus using an inexpensive and highly efficient solid line-shaped write device. SOLUTION: A group of LED heads is constituted of a plurality of LED heads (solid line-shaped write devices) 50, 51 arranged in an axial direction (breadthwise direction) of a photosensitive body (i.e., arranged zigzag). A maximum photosensitive breadth in the axial direction of the photosensitive body can be divided and exposed separately by the LED heads 50, 51. Alternatively, end parts of exposable areas by the plurality of LED heads arranged zigzag in the axial direction of the photosensitive body may be overlapped in the axial direction of the photosensitive body. Otherwise, the group of LED heads is constituted of LED heads of an odd number not smaller than 3 and arranged zigzag so that a count of LED heads is larger at the upstream side than at the downstream side in a turning direction of the photosensitive body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital copying machine, a printer, and a digital copier using a solid line writing device.
The present invention relates to various image forming apparatuses such as an AX apparatus.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus capable of forming an image having a width of A2 or more, a writing apparatus (solid-state) using a solid linear writing device such as an LED head by a scanning writing apparatus using a laser diode or the like. It is advantageous to use a linear writing device). This is because the number of pixels in one line is larger in a wide image formation than in a small-sized image, and thus, for example, the lighting frequency of a laser diode and the rotation speed of a polygon scanner (polygon mirror) become faster. is there.

[0003]

However, as the image forming width of the solid-state linear writing device becomes wider,
The number of light-emitting elements (LEDs, etc.) and driver ICs are increased, and the arrangement accuracy and production yield are rapidly reduced, and the unit cost of the components is much higher than that of small-sized ones.

The present invention has been made in view of the above problems, and has as its object to provide an inexpensive and high-performance image forming apparatus using a solid-state linear writing device.

[0005]

According to the present invention, there is provided an image forming apparatus having a rotatable photosensitive member and an exposing means for exposing a surface of the photosensitive member to form an electrostatic latent image. In the forming apparatus, the exposure means (solid line writing device) is constituted by a plurality of solid line writing devices arranged along the axial direction of the photoreceptor, and the maximum photosensitive width in the axial direction of the photoreceptor is determined by a plurality of the linear writing devices. In this case, divisional exposure can be performed by a solid line writing device.

Further, the plurality of solid line-shaped writing devices are arranged in a staggered manner along the axial direction of the photosensitive member, and the end of the area that can be exposed by each of the solid line-shaped writing devices is positioned in the axial direction of the photosensitive member. It is good to overlap with. In this case, the exposure means is constituted by an odd number of solid line writing devices of three or more, and the number of each solid line writing device is larger on the upstream side than on the downstream side in the rotation direction of the photoconductor. It is good to arrange them in a zigzag pattern. In addition, it is desirable to arrange the solid line writing devices adjacent to each other so that their light emitting lines are close to each other.

According to the image forming apparatus of the present invention, the exposing means can divide and expose the maximum photosensitive width in the axial direction of the photoconductor by a plurality of solid linear writing devices arranged along the axial direction of the photoconductor. Therefore, it is possible to drastically reduce the component cost as compared with an image forming apparatus that performs exposure using an exposure unit including one solid line writing device.

Further, the plurality of solid line writing devices are arranged in a zigzag pattern along the axial direction of the photoreceptor, and the end of the area that can be exposed by each of the solid line writing devices is positioned in the axial direction of the photoreceptor. When the one line is finally formed, it is possible to simplify the mounting adjustment of each solid line-shaped writing device in the axial direction of the photoconductor without generating a missing image or a white streak.

In this case, the exposure means is constituted by an odd number of solid line writing devices of three or more, and the number of each solid line writing device is such that the number of the solid line writing devices is more upstream than downstream in the rotation direction of the photosensitive member. By staggering them so that the number of images increases, it is also possible to reduce the capacity of a memory for delaying an image in the rotation direction of the photoconductor, which is required when finally forming one line.

Further, since the side surface of a normal solid line writing device (LED head) has an L-shape, the solid line writing devices adjacent to each other are oriented such that their light emitting lines are close to each other (180). Arrangement), the emission line of each solid-state linear writing device is re-shortened, and finally the
It is also possible to minimize the capacity of a memory for delaying an image in the rotation direction of the photoconductor, which is necessary for line conversion.

[0011]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 4 is an overall configuration diagram illustrating an example of a mechanical unit of the printer according to the embodiment of the present invention.

In the figure, reference numeral 2 denotes a rotatable (rotatable) photosensitive member, and a plurality of LED heads (solid line writing device) serving as exposure means (solid line writing device) directly related to the present invention are provided around the photosensitive member. An LED head group 1, a charging charger 3, a developing unit 4, a transfer charger 5, a transfer belt 11, and a cleaning device 6 are arranged.

The transfer paper 8 is inserted into the paper feeding device 7. The transfer paper 8 is separated and fed one by one by a pickup roller 9, and is conveyed to an image forming unit by a roller 10.
The photoreceptor 2 rotates in the direction indicated by the arrow, and charges are uniformly accumulated on the surface of the photoreceptor 3 by the charging charger 3, and exposure is performed by the LED head group 1 in accordance with image data to form an electrostatic latent image. Is done.

Further, the latent image is visualized by toner adhesion in the developing device 4 to become a toner image. After the toner image is transferred to the transfer paper 8 by the transfer charger 5 and the transfer belt 11, The transfer paper is conveyed to the fixing device 12, and
After the toner image is thermally fixed, the toner image is discharged to the paper discharge tray 13.

FIG. 5 is a sectional view showing an example of a mechanism of one LED head in the LED head group 1. As shown in FIG. In the drawing, reference numeral 36 denotes a printed circuit board, on which the LE
A D chip 35 and a driver IC 34 for driving and driving each LED thereof are mounted, and each LED and a driving circuit are wire-bonded so as to be one-to-one.

The housing 33 is provided on the printed circuit board 3.
When each LED on 6 emits light, the LED light is
Rod lens array 37 for imaging at the same magnification on the surface of
Holding. Therefore, the cross section of the LED head is usually L
It becomes a character shape.

FIG. 6 is a block diagram showing an example of a control system of one LED head in the LED head group 1. As shown in FIG.
In the figure, image data SDATA is input to a shift register 39, shifted and transferred to a desired position by a signal SCLK, and temporarily stored in a flip-flop circuit (F / F) 40 by a signal LAT when the transfer is completed.

Next, during the active "L" period, a signal / STB ("/" indicates low active, which is indicated by an overline) is applied to each LED through the gate 41 and the transistor 42. Each LED 38 of the chip 35
Illuminates according to the image data SDATA.

Here, the LED chip 35 is generally 64
LEDs are integrated in a line. That is, 1
(N × 64) dots (dot)
Are arranged along the axial direction (width direction) of the photoconductor 2. This light emitting point has, for example, an exposure density of 400 dp.
i, when the maximum exposure width is 297 mm (A3 size),
It is sufficient that 64 × 76 = 4864 dots including a margin. When the maximum exposure width is 841 mm (A0 size), at least 13,244 dots are required.

[0021] Mounting these components so that all of them are connected by wires and all the LED lights are accurately imaged on the surface of the photosensitive member 2 is performed in comparison with the case where a relatively small-sized LED head is used. It is much more difficult, and the yield of good products is very poor. Furthermore, most of the image forming apparatuses currently on the market are A3 size or smaller,
Production lots also vary widely. For this reason, the component cost is much higher than a configuration in which the maximum exposure width is divided and exposed by a small-sized LED head.

Therefore, in the printer of this embodiment, L
The ED head group 1 is composed of a plurality of LED heads arranged along the axial direction of the photoconductor 2, and the maximum exposure width (maximum photosensitive width) of the photoconductor 2 in the axial direction is divided by a plurality of LED heads. Making it possible.

FIG. 1 is a view showing each LED constituting the LED head group 1.
FIG. 4 is an explanatory diagram illustrating a first example of an array of ED heads. In this example, two LED heads 50 and 51 constituting the LED head group 1 are arranged in a staggered manner along the axial direction (width direction) of the photoconductor 2. Therefore, image data to be exposed by the LED head 50 is cut out, and the image data is delayed by an amount corresponding to the image delay amount using a memory.

Further, each of the LED heads 50 and 51 is
LED light from the light emitting point of the n-th dot of the D head 50 and L
The ED head 51 is arranged so that the pitch with the LED light from the light emitting point of the first dot of the ED head 51 matches a predetermined exposure density. Thereby, an electrostatic latent image of (2 × n) dots can be formed in one line on the surface of the photoconductor 2.

Each of the LED heads 50 in the arrangement shown in FIG.
According to the printer that performs exposure using the LED head group 1 composed of 51, the cost of parts can be dramatically reduced as compared with a printer that performs exposure using one LED head.

FIG. 2 is a diagram showing each LED constituting the LED head group 1.
FIG. 9 is an explanatory diagram showing a second example of the arrangement of the ED heads. In this example, three LED heads 52, 53, and 54 constituting the LED head group 1 are arranged in a staggered manner along the width direction of the photoconductor 2. For this reason, image data to be exposed by the LED head 53 is cut out, and the image data is delayed using a memory by an amount corresponding to the image delay amount.

The exposing areas of the LED heads 52 and 53 and the exposing areas of the LED heads 53 and 54 are overlapped in the width direction of the photosensitive member 2. Here, the areas that can be exposed by the LED heads 52 and 53 overlap each other by the overlap area X.
Similarly, the areas that can be exposed by the LED heads 53 and 54 are overlapped by the overlap area Y.

In this case, each LED head 52, 5
Image data for exposing at 3, 54 are cut out and switched within the overlapping area X, Y, so that an electrostatic latent image of (3 × n−X−Y) dots is formed in one line on the surface of the photoconductor 2. Can be formed. Each LED in the array shown in FIG.
According to the printer that performs exposure using the LED head group 1 including the heads 52, 53, and 54, the component cost is dramatically reduced as described above, compared to a printer that performs exposure using one LED head. can do.

Further, since the LED head group 1 is arranged in a staggered manner such that the number of LED heads is larger on the upstream side than on the downstream side in the rotation direction of the photosensitive member 2, when the LED head group 1 is finally formed into one line. It is also possible to reduce the capacity of the memory required for delaying the image in the rotation direction of the photoconductor 2 required for the above. Furthermore, since the end portions of the areas that can be exposed by the respective LED heads are overlapped in the width direction of the photoconductor 2, the final photolithography can be performed without causing image missing or white streaks. The mounting adjustment of each LED head in the width direction can be simplified.

FIG. 3 is a diagram showing each LED constituting the LED head group 1.
FIG. 11 is an explanatory diagram showing a third example of the arrangement of the ED heads. The LED head group 1 of this example is almost the same as that shown in FIG. 2, except that the LED heads 53 are rotated by 180 degrees, and the LED heads adjacent to each other are arranged so that the light emitting lines thereof are close to each other. I have. This is because the shape of the LED head is used to make the gap between the light emitting lines of each LED head the shortest distance, so that the image delay amount is reduced and the memory capacity can be reduced to the minimum.

However, by rotating the LED head 53, the order of the image data for exposure is reversed. Therefore, after cutting out the image data for exposure,
By performing mirror processing using line memory,
An electrostatic latent image of (3 × n-XY) dots can be formed in one line on the surface of the photoconductor 2. Both the rotational direction and the width direction of the photoconductor 2 can be corrected by using a memory.

The embodiment in which the present invention is applied to a printer using an LED head has been described above. However, the present invention is not limited to this, and other solid line writing such as a phosphor dot array, a shutter array, and a thermal head can be used. The present invention can be applied not only to printers using devices, but also to various image forming apparatuses such as digital copiers and facsimile apparatuses using the above-described solid line writing devices.

[0032]

As described above, according to the present invention, it is possible to provide an image forming apparatus using an inexpensive and high-performance solid line writer.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a first example of an arrangement of each LED head constituting a LED head group 1 of FIG. 4;

FIG. 2 is an explanatory diagram showing a second example of the arrangement of the LED heads that also make up the LED head group 1.

FIG. 3 is an explanatory diagram showing a third example of the arrangement of the LED heads that also constitute the LED head group 1.

FIG. 4 is an overall configuration diagram illustrating an example of a mechanical unit of the printer according to the embodiment of the present invention.

FIG. 5 shows one LED of the LED head group 1 of FIG. 4;
FIG. 3 is a cross-sectional view illustrating an example of a head mechanism.

FIG. 6 also shows one LED of LED head group 1
FIG. 3 is a block diagram illustrating an example of a head control system.

[Explanation of symbols]

 1: LED head group 2: Photoconductor 50 to 54: LED head

Claims (4)

[Claims] 1. An image forming apparatus comprising: a rotatable photosensitive member; and an exposing means for exposing a surface of the photosensitive member to form an electrostatic latent image, wherein the exposing means is arranged in an axial direction of the photosensitive member. An image forming apparatus comprising: a plurality of solid line writing devices arranged along a line, wherein the maximum photosensitive width in the axial direction of the photoconductor can be divided and exposed by the plurality of solid line writing devices. apparatus. 2. The image forming apparatus according to claim 1, wherein
The plurality of solid line writing devices are arranged in a staggered manner along the axial direction of the photoconductor, and the ends of the areas that can be exposed by the solid line writing devices overlap in the axial direction of the photoconductor. An image forming apparatus comprising: 3. The image forming apparatus according to claim 2, wherein
The exposure means is constituted by an odd number of three or more solid linear writing devices, and the number of each solid linear writing device is larger on the upstream side than on the downstream side in the rotation direction of the photoconductor. An image forming apparatus, which is arranged in a staggered pattern. 4. The image forming apparatus according to claim 2, wherein
An image forming apparatus comprising: a plurality of solid line writing devices adjacent to each other arranged such that their light emitting lines are close to each other.