JPS6349463A - Gradation recorder - Google Patents

Abstract

PURPOSE:To enable high quality and high resolution gradation recording, by varying the size of recording dots according to the output from an exposure control circuit. CONSTITUTION:An exposure control circuit 18 is constructed with a gradation data/light emission time converter 19 for converting a gradation data into a light emission time data of such as a LED 95, a time control circuit 20 for controlling the light emission time and a latch circuit 24. Pixel unit gradation data are contained in a gradation data memory 17 and read out synchronously with the clock of a print clock generator 21, then fed to the gradation data/light emission time converter 19 which produces a light emission data. The light emission data is transferred serially to shift registers 20 (20-1-20-n) at high speed, then transferred in the vertical direction by means of a parallel load signal synchronized with a print sub-clock 22 and held in the latch circuit 24 so as to control the emission, non-emission state of the LED array 95 for every print sub-clock unit through respective drivers 23. Since the gradation is represented within a single dot, a high quality gradation can be represented without the sacrifice of resolution.

Description

[Detailed Description of the Invention] [Summary] The present invention solves the problem that when performing gradation recording in an electrophotographic recording device, the resolution decreases when one pixel is configured using a plurality of dots. By controlling the light emitting time of the device and changing the size of the recording dot,
It is designed to perform high-resolution gradation recording.

[Industrial application field]

The present invention relates to an electrophotographic recording apparatus, and particularly to an L
Obtain high-resolution gradation images using an ED array or EL panel as an exposure means! ugJl recording device.

2. Description of the Related Art In recent years, with the diversification of information, there has been a demand for a recording device that can record color characters, symbols, images, etc. at high speed. These devices require gradation recording, and in particular, high-resolution gradation recording is required.

[Conventional technology]

FIG. 7 is a block diagram of a conventional multicolor recording apparatus, which was already proposed by the present applicant in Japanese Patent Application No. 60-16051.

This device uses two photosensitive drums to form toner images of two different colors on each photosensitive drum and transfer them onto the same recording paper to obtain a multicolor recorded image made of four toner colors. It is.

In the figure, after a first photosensitive drum 71 is charged using a first charger 73, a first toner image corresponding to first color information is made visible by a first exposure section 74 and a first development section 75. After forming an image (yellow) and recharging it with the recharging device 76, the second exposure section 77 and the second development section 78 generate a second toner image visible image (magenta) corresponding to the second color information. are formed, and these visible images are transferred all at once onto the recording paper 94 by the first transfer section 79.

On the other hand, an initial charger 83 is placed on the second J5 optical drum 72, with the operation timing shifted from that on the first photosensitive drum 71 side.
After charging is performed using the third exposing section 84 and the third developing section 85, a third visible toner image (cyan) corresponding to the third color information is formed, and then the third visible toner image (cyan) is formed by the recharging device 86. After performing this, a fourth visible toner image (black) corresponding to the fourth color information is formed by the fourth exposing section 87 and the fourth developing section 88, and these toner images are combined with the first toner image. The second transfer unit 8 transfers the second toner image onto the recording paper 94.
9 to perform batch transfer.

After that, the multicolor toner image transferred onto the recording paper 94 is
By thermally fixing, for example, in the fixing section 93, permanent multicolor recording can be obtained.

Figure 8 shows the conventional exposure section (same as in Figure 7, (1°1
The configuration diagram of a representative example of the first exposure section 74 to the fourth exposure section 87 shown in FIG. In the figure, an LED array or EL panel 95 is provided opposite the first photosensitive drum 71, and a SELFOC lens 96 is used to display the LED array or EL panel 95.
5 is projected onto the first photosensitive drum 71 and selectively causes the LED array or EL panel 95 to emit light, thereby exposing a desired pattern.

For gradation recording, there is a method of performing area gradation using a density pattern method.

FIG. 9 is a diagram for explaining the density pattern method using 4×4 dots. In this case, one pixel (as shown in Figure 81, is assembled with a 4 x 4 dot darkness value matrix according to the gradation data, Figure (b) is level 02, Figure 1 is level 1 (Figure d1 is level 2. (01 The AIF1 diagram is level 4. The CR1 diagram can represent 17 levels of gradation based on area gradation up to level 16.

Further, as another gradation recording method, a dither method (not shown) is known. The dither method allows gradation recording with higher resolution than the density pattern method.

[Problem that the invention seeks to solve]

When performing area gradation using the density pattern method, the resolution is a fraction of the original resolution of the recording device (1/4 if one pixel is composed of 4 x 4 16 dots as shown in Figure 9). This has the disadvantage that the image becomes rough and the image quality deteriorates.

In addition, when performing area gradation using the dither method, it is possible to obtain relatively high resolution compared to the density pattern method, but the gradation quality deteriorates, resulting in rough images and images containing noise. There is a drawback.

[Means for solving problems]

As shown in the configuration diagram of FIG. 1, the gradation recording device of the present invention has the following features:
It is characterized in that an exposure control circuit 18 is provided to control the exposure amount in stages according to gradation data, and the size of the recording dot is changed by the output of the exposure control circuit 18.
The light source of the exposure control circuit 18 is an LED array or an EL.
This is realized by using a panel (hereinafter simply referred to as LED or the like) 95 and providing a gradation data/light emission time converter 19 that controls the light emission time stepwise to control the exposure amount.

[Effect]

The image data indicating the gradation is converted into luminescence time data by the gradation data/emission time converter ai, and the luminescence time data is converted into luminescence time data by the luminescence time control circuit 2.
0 shift registers 20-1 to 20-n.

The light emitting time of the LED etc. 95 is changed based on this light emitting time data. As shown in FIG. 2, when the light emission time changes, the amount of exposure applied to the photosensitive drum changes, and the size of the dot changes. As a result, the image data indicating the gradation is converted to the size of a dot, making it possible to perform area gradation in units of one dot.

FIG. 2 is a diagram showing changes in exposure amount and dot shape due to changes in light emission time of LEDs, etc., where the vertical axis represents the exposure amount and the horizontal axis represents the dot diameter (-), and the exposure required for development is shown. Figure (a) shows the case where the light emission time is long.

In this case, the amount of exposure projected onto the photosensitive drum through the lens is large (because the amount of toner that adheres during development is large, large dots are formed).

Figure fc1 shows the case where the light emission time is short, the amount of exposure projected onto the photosensitive drum through the lens is small, and the amount of toner that adheres during development is small, so the size of the dot is reduced.

The fb1 diagram shows the case where the light emission time is between the one in the 81 diagram and the fc1 diagram.

In order to perform gradation recording based on this principle, there is no need to configure a plurality of pixels, and the resolution can maintain its original performance.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

In order to make the explanation of the configuration and operation easier to understand, the same parts are given the same reference numerals throughout the drawings, and their repeated explanation will be omitted.

FIG. 3 is a diagram showing changes in dot diameter depending on light emission time. This figure is a graph of actually measured data, with the dot diameter p plotted on the vertical axis and the light emission time ms plotted on the horizontal axis.・By changing the light emission time as shown in the figure, 0.6 ms
If it becomes shorter than the vicinity, the size of the dot changes significantly.

In order to perform gradation recording based on this principle, as shown in FIG. The exposure control circuit 18 is composed of a time control circuit 20 that controls the light emission time of an LED or the like 95 and a latch circuit 24.

Since the recording apparatus to which the present invention is applied has the same structure as the conventional example shown in FIG. 7 except for the exposure section, one embodiment of the present invention will be described here by taking up the exposure section. FIG. 1 is a block diagram of a main part of the gradation recording apparatus of the present invention, and FIG. 4 is a signal waveform diagram of an exposure control circuit.

The gradation data memory 17 stores gradation data for each pixel, and the gradation data is read out in synchronization with the clock of the print clock generator 21. This gradation data is input manually to the gradation data/emission time converter 19, and emission time data is output. The gradation data/emission time converter 19 is
Simply a P-ROM or RO containing a conversion table.
It is possible to configure it by M.

The light emission time data is serially transferred at high speed to shift registers 20 (20-1 to 20-n) forming the time control circuit 20. The light emitting time data in the shift register 20 is transferred vertically by a parallel load signal synchronized with the print subclock 22 and held in the latch circuit 24, and the light emitting/non-emitting state of the LED array 950 is transferred to each driver in print subclock units. 23.

For example, in FIG. 4, when the gradation data is level O, the emission time is zero, and when the gradation data is level 1, the emission time is the length of one print subcrofter clock. If the gradation data is expressed in 3 bits like this, the light emitting time is 8
There are stages, and eight different sizes of dots are formed, including zero.

As described above, according to the gradation recording apparatus of this system, gradation can be expressed within one dot, so high-quality gradation can be expressed without reducing resolution.

Furthermore, since there is no reduction in resolution, there is an advantage that there is no need to use particularly high-resolution LEDs, etc. 95 to be used.

In addition, in the above explanation, it was assumed that the size of the dot was changed by controlling the light emitting time.
It can be easily inferred that the same effect can be obtained by controlling the light emission drive voltage or light emission drive current of the ED etc. 95.

FIG. 5 shows a block diagram of a control circuit according to another embodiment of the invention. In the figure, the difference from FIG. and shift register 25
It is composed of Therefore, the exposure control circuit 26 can reduce the scale of the exposure control circuit 18 in FIG. 1 to a fraction of a second.

FIG. 6 shows a signal waveform diagram of the exposure control circuit 18 in FIG. In the figure, a gradation data/emission time converter 19
The gradation data from the gradation data memory 17 and the sub-clock count value from the sub-clock counter 25 are input to the gradation data memory 17 .

The gradation data/emission time converter 19 converts the gradation data and subclock count value into the next one every subclock.
Data for controlling light emission and non-light emission of the LED array is created during the subclock and is serially transferred to the shift register 20. This data is held in the launch circuit 24 by a launch signal synchronized with the subclock, and the driver 23 controls whether or not the LED array 95 emits light for one subclock.

The same gradation data is read out until the next print clock 21 is generated. According to the above configuration, a circuit configuration having the same function as that shown in FIG. 1 can be more easily realized.

〔Effect of the invention〕

As explained in detail above, according to the gradation recording device of the present invention, since area gradation is performed by varying the light emitting time of the LED or the like and changing the size of the dot itself, high-quality, high-resolution gradation can be achieved. Records can be made.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the main part of the gradation recording device of the present invention, Fig. 2 is a diagram showing changes in exposure amount and dot shape due to changes in light emission time of LEDs, etc., and Fig. 3 is a diagram showing changes in dot diameter depending on light emission time. 4 is a signal waveform diagram of the exposure control circuit in FIG. 1, FIG. 5 is a block diagram of another embodiment of the present invention, and FIG. 6 is a signal waveform of the exposure control circuit in FIG. 5. 7 is a block diagram of a conventional multicolor recording apparatus, FIG. 8 is a block diagram of a conventional exposure section, and FIG. 9 is an explanatory diagram of a conventional density pattern type gradation recording method. In the figure, 18 is an exposure control circuit, 19 is a gradation data/
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Claims (3)

[Claims] (1) The electrophotographic recording device is provided with an exposure control circuit (18) that controls the exposure amount in stages according to the gradation data, and the size of the recorded dots is changed by the output of the exposure control circuit (18). A gradation recording device characterized by: (2) The gradation recording apparatus according to claim (1), wherein an LED array or an EL panel is used as a light source of the exposure control circuit (18). (3) The system according to claim (1), characterized in that the exposure control circuit (18) is provided with a gradation data/light emission time converter (13) that controls the light emission time in stages. Key recording device.