JPH0259364A - Image recording device - Google Patents

Abstract

PURPOSE:To make possible the recording of data at high speed and density by employing exposure devices with exposure points staggered in a main scan and subscan directions and performing an exposure at each recording position at different timing within a single scanning operation. CONSTITUTION:An LED array 1 consists of four light-emitting diodes (LED) 3 arranged, as a recording light source, at an interval S in the main scan direction of the photosensitive surface. The length of each main scan direction equals the interval S. The LEDs 3 constitutes an exposure device with a slit or a lens which condenses the light to the photosensitive surface 2. The photosensitive surface 2 is realized as a photosensitive element drum which rotates in the main scan direction. To record a single image, the photosensitive surface 2 is scanned only once, and its main scanning operation is performed by moving the photosensitive surface 2 in the main scan direction. The subscanning operation is achieved by moving the LED array 1 in the subscan direction. The condensing point of the light from each LED 3, that is, the exposure point of each exposure device is located at a position deviated by an interval A on the same main scanning line. This interval S corresponds to an image interval (interval between recording positions) on each scanning line.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an image recording apparatus that records an image on a photosensitive surface by exposing the photosensitive surface according to image information.

2. Description of the Related Art A technique is known in which one or more recording light sources are driven by image information and the light emitted from the recording light sources is focused onto a photosensitive surface using a slit or a lens to perform recording exposure.

Conventionally, this type of image recording apparatus performs a scanning operation of the photosensitive surface for image recording only once, regardless of whether there is one recording light source or multiple recording light sources, and during this scanning operation period, the photosensitive surface is The configuration was such that recording exposure was performed only once for each recording position.

Problems to be Solved by the Invention However, with this configuration, there is a problem in that it is difficult to increase the scanning speed and scanning line density.

In other words, a certain amount of exposure light is required to obtain a certain recording density, but as scanning speed increases, the exposure time for each recording position inevitably becomes shorter, and this works to reduce the amount of exposure light. . Similarly, as the scanning line density increases, the spot diameter of the recording light on the photosensitive surface must necessarily be reduced, which also works to reduce the amount of light. in this way,
It has been difficult to increase the scanning speed and scanning line density in order to secure the necessary amount of exposure light.

Possible solutions to this problem include increasing the amount of light from the recording light source and performing a scanning operation multiple times to record one image.

However, the method of increasing the amount of light from the light source requires that the light emitting diode, laser diode, or the like used as the recording light source become higher in output, and if the output is increased, there are problems such as lifespan and heat generation.

Furthermore, a method in which scanning operations are performed multiple times for recording one image enables high-density recording. However, since the total time of the scanning operation increases, the actual scanning speed decreases.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an image recording apparatus capable of high-speed, high-density recording while ensuring a necessary amount of exposure light.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention aims at reciprocating in the main scanning direction or sub-scanning direction at the exposure point on the photosensitive surface during one scanning operation of the photosensitive surface for image recording. The apparatus is constructed such that recording exposure of the same image information is sequentially performed by each of the plurality of exposure means shifted in the same direction when the exposure point coincides with the same recording position on the photosensitive surface.

Because recording exposure is performed multiple times for each recording position on the active photosensitive surface, even if the time per exposure becomes shorter as the scanning speed increases, or the spot diameter becomes smaller as the scanning line density increases, By appropriately selecting the number of recording exposures, the required amount of exposure light can be obtained.

In addition, instead of performing multiple scanning operations for image recording, multiple exposure means whose exposure points are shifted from each other in the main scanning direction or the sub-scanning direction are used, and the time is reduced within one scanning operation period. Since each recording position is sequentially exposed while being shifted, even if the number of exposures is increased, the image recording time does not increase, that is, the scanning speed does not decrease substantially.

Therefore, the present invention enables high-speed, high-density image recording with the above-described configuration without causing a shortage in the amount of exposure light or the recording density.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory diagram of the configuration of an exposure means and recording exposure in an image recording apparatus according to an embodiment of the present invention, and 1 is an LE
D array, 2 is a photosensitive surface.

The LED array 1 has four light emitting diodes (LEDs) 3 as recording light sources arranged at intervals S in the main scanning direction of photosensitive surface scanning, and the size of each in the main scanning direction is also equal to the interval S. Each LED 3 constitutes an exposure means together with a slit or lens (integrated with or separate from the LED array 1, but omitted in the figure) for converging its light emission onto the photosensitive surface 2.

The photosensitive surface 2 is realized, for example, as the surface of a photosensitive drum that rotates in the main scanning direction.

The scanning operation of the photosensitive surface 2 is performed only once to record one image, but the main scanning is performed by moving the photosensitive surface 2 in the main scanning direction (rotation of the photosensitive drum), and the sub-scanning is performed by moving the photosensitive surface 2 in the main scanning direction (rotation of the photosensitive drum). This is performed by moving the LED array 1 in the sub-scanning direction.

The focal point of the light emission of each LED 3, that is, the exposure point of each exposure means is at a position shifted by the interval A on the same main scanning line. This interval S corresponds to the pixel interval (interval between recording positions) on each scanning line.

The recording operation during the scanning period of one main scanning line L will be described below.

LED3. When the exposure point of the exposure means consisting of matches the recording position A of the first pixel, L E
D 3 + is driven and recording exposure is performed.

The exposure point of the exposure means consisting of the next LED 32 is at recording position A.
When it matches, the image information of the first pixel is used.
32 is driven, and the second recording exposure is performed. At the same time, since the exposure point of the exposure means consisting of the LED 31 coincides with the recording position B of the second pixel, the LE
D31 is driven, and the first recording exposure of recording position B is performed.

When the exposure point of the exposure means consisting of the LED 3g coincides with the recording position A, the LED 33 is driven by the image information of the first pixel, and the third recording drive of the recording position A is performed. At the same time, LED3. ．． Since the recording point of the exposure means consisting of 3□ coincides with the recording position C9B of the third pixel and the second pixel,
LED3. ．． 3□ is driven by the image information of the third pixel and the second pixel, respectively, and the second recording drive of the recording position B and the first recording drive of the recording position C are performed.

Similarly, the recording position of each pixel on the scanning line L is determined by four exposure means. It is exposed 14 times.

Then, exposure of four consecutive recording positions is performed simultaneously. Therefore, even if the main scanning speed is increased to four times the conventional speed, 1
Although the exposure time for each exposure is one fourth of that of the conventional method, the total time of the four exposures is the same as that of the conventional method, so if the amount of light emitted from the LED 3 is the same, the required amount of exposure light can be obtained. This also applies when the spot diameter is reduced in order to increase the scanning line density. In this way, high-speed, high-density recording is possible without causing insufficient recording density without particularly increasing the light intensity of the recording light source.

When the fourth recording exposure of the recording position of the last pixel of the scanning line L is completed as described above, the same recording exposure is performed for the next scanning line by moving the LED array I. Note that the sub-scanning can also be performed by moving the photosensitive surface 2.

FIG. 2 is a schematic configuration diagram of a drive control circuit for driving the LED 3 as described above.

In Fig. 2, a is a binary image signal representing serial image information in pixel units, and b is 1/1 of the pixel transfer period of image signal a.
This is a basic clock with 0 cycles. 5 is a clock C whose frequency is the same as the pixel transfer period of the image signal a by dividing the basic clock b.
6 is a frequency dividing circuit that creates a clock C.
It is a flip-flop that cannot be synchronized to the 7 is a clock C for the image signal d after synchronization by the flip-flop 6.
This is a shift register that sequentially shifts the input data at the timing of . This shift register 7 has 2 bits for the image signal d.
It is provided to obtain a pixel signal e before a pixel, a pixel signal f from four pixels before, and a pixel signal g from six pixels before.

8 is a driver circuit for driving each LED 3.

Reference numerals 9 denote shift registers that receive and shift the image signals L e + L g at the timing of the clock C, respectively. 10 selects the output signal of one bit of each shift register 9, and outputs the image signal for driving each LED 3;
This is a selector that outputs as 1+'J+k. 1
1 is a switch for specifying the selection bit of each selector 10. By switching the selection bit of the selector 10, the driving time of each LED 3 can be moved forward or backward in units of one cycle of the clock C, and the timing can be adjusted so that the recording exposure is performed in the positional relationship as explained in FIG. 1. .

The operation of this drive control circuit is as follows.

The image signal a is synchronized by the flip-flop 6 and sequentially shifted to the shift register 7, and the image signal d+eHLg shifted by two pixels is sequentially shifted to the corresponding shift register 9. Then, the image signal whose timing is corrected by the shift register 9 and the selector 10,
it L k is obtained, and each LF:D3 is driven by each driver circuit 8 according to this. Thus, the first
Recording exposure as explained in the figures is performed.

FIG. 3 is an explanatory diagram of the structure of an exposure means and recording exposure in an image recording apparatus according to another embodiment of the present invention, in which 1a is an LED array and 2 is a photosensitive surface.

The LED array 1a includes two LEDs as recording light sources.
3 are arranged at intervals S in the sub-scanning direction.

Each LED 3 constitutes an exposure means together with a lens or a slit, and its size in the sub-scanning direction is equal to the interval S.

In this embodiment as well, image recording is performed by performing the same scanning operation only once as in the first embodiment, but the recording exposure method is different as follows.

In the first main scanning line L, when the exposure point of the exposure means, which may also be the LED 35, coincides with an arbitrary recording position on the main scanning line L, the LED is activated according to the image information of the corresponding pixel.
3s is driven, and the first recording exposure is performed for that recording position. Similarly, when the first recording exposure is performed to the last recording position of the main scanning line, the LED array 1a moves in the sub-scanning direction, and the LED array 1a moves to the next main scanning line L2. Recording exposure is performed by an exposure means consisting of:

When the recording exposure of the main scanning line L2 is completed, the sub-scanning movement is performed. This time, the main scanning line L3 is scanned by the exposure point of the exposure means consisting of the LED 35, and each recording position is subjected to recording exposure according to the image information of the corresponding pixel.

At the same time, the main scanning line L1 is scanned by the exposure point by the exposure means consisting of the LED 3a, and at this time the LED 36 is driven according to the image information corresponding to the main scanning line L1. That is, simultaneously with the recording exposure of an arbitrary recording position A3 of the main scanning line L3, the second recording exposure of the corresponding recording position A1 of the main scanning line memory is performed.

In this way, the recording exposure for two lines is performed simultaneously by two exposure means whose exposure points are shifted in the sub-scanning direction, and the recording exposure for each recording position of each line is performed twice according to the same image information, so the main scanning speed Even if the total exposure time is doubled, the total exposure time remains the same, so there is no shortage of exposure light. This also applies when the spot diameter is reduced.

Therefore, according to this embodiment, high-speed, high-density recording is possible without causing a shortage in the amount of exposure light.

FIG. 4 is a schematic configuration diagram of a drive control circuit for driving the LED 3 in FIG. 3, where a is an image signal, C is a clock synchronized with the pixel transfer lock of the image signal a, and m is a This is a phase signal synchronized with line transfer of image signal a. 8 is each L
This is a driver circuit for ED3.

As is clear from the explanation with reference to FIG. 3, in this embodiment, it is necessary to accumulate image information on a line-by-line basis. Therefore,
Two line memories 13 and 14 are used to store image information for one line for the LED 35, and L E D 3 a
Four line memories 15, 16, 17, and 18 are provided to store image information for one line. 1
9 is a memory control circuit for controlling writing and reading of each line memory. The memory control circuit 19 switches the operation of the line memory on a line-by-line basis, but the valid section of the line that is not to be switched is identified based on the phase signal.

The operation of this drive control circuit is as follows.

(2) Information on the image signal a of the th line When the image information is input, this image information is sequentially written into the line memo 'J 13.15 at the timing of the clock C under the control of the memory control circuit 19.

When the image information for the second line is input, this image information is sequentially written into the line memories 14 and 16. At the same time, the image information of the first line is sequentially read out from the line memory 13,
According to this, LED 35 is driven.

When the image information for the third line is input, this image information is sequentially written into the line memories 13 and 17. At the same time, the image information of the second line is read from the line memory 14, and the LED 3s is driven accordingly.

When the image information for the fourth line is input, this image information is sequentially written into the line memories 14 and 18. During this period, the image information of the third line is read out from the line memory 13,
The LED 3a is driven according to this image information. Furthermore, the image information of the first line is read out from the line memory 15, and the LED 36 is driven accordingly. Here, the second recording exposure for the first line is performed.

When the image information for the fifth line is input, this image information is stored in the line memory 13. 15 in sequence. At the same time, image information for the fourth line is read from the line memory 14, and image information for the second line is read from the line memory 16.

At this stage, the second recording exposure for the second line is performed.

Thereafter, by similar operations, recording exposure as explained with reference to FIG. 3 is executed.

Note that the number of exposure means may be increased or decreased as necessary. Further, the configuration of the exposure means may be changed as appropriate, such as using an element other than an LED as a recording light source. Furthermore, the present invention can be similarly applied to devices that record multivalued images.

Effects of the Invention As is clear from the above description, the present invention uses a plurality of exposure means whose exposure points are mutually shifted in the main scanning direction or the sub-scanning direction, and shifts the time within one scanning operation period. Since recording exposure is performed multiple times according to the same image information for each recording position, high-speed, high-density image recording is possible without increasing the light intensity of the recording light source and without causing a shortage of exposure light. It has the following.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the configuration of an exposure means and recording exposure method in an image recording apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic block diagram of a drive control circuit for controlling the exposure means in FIG. 1. , FIG. 3 is an explanatory diagram of the configuration of the exposure means and recording exposure method in an image recording apparatus according to another embodiment of the present invention, and FIG. 4 is a schematic diagram of a drive control circuit for controlling the exposure means in FIG. 3. It is a block diagram. 1.1a...LED array, 2...photosensitive surface, 3...
・Light emitting diode (LED), 5... Frequency dividing circuit, 6
...Flip-flop, 7,9...Shift register, 8...Driver circuit, 10...Selector, 11.
...Switch, 1318...Line memory, 19...
Memory control circuit.

Claims (1)

[Claims] A plurality of exposure means whose exposure points on the photosensitive surface are shifted from each other in the main scanning direction or the sub-scanning direction, and each of the plurality of exposure means during a period of performing one scanning operation of the photosensitive surface for image recording. , means for sequentially performing recording exposure of the same image information when the exposure point coincides with the same recording position on the photosensitive surface.