JPH0254672A - Picture recorder - Google Patents

Abstract

PURPOSE:To increase the gradation at picture recording by obtaining an information signal to control a prescribed illuminance and the lighting time based on a picture read signal and controlling the running speed of a photosensitive material corresponding to the quantity of information of the information signal. CONSTITUTION:A current-voltage converter 5 obtains a voltage V1 whose level is changing and an analog/digital converter 6 converts the voltage V1 into a digital signal V2. A signal processing circuit 7 obtains an 8-bit information signal V3 controlling the gradation of recording density from the digital signal V2. When the information signal V3 represents a high gradation number, the number of recording scanning lines subject to intensity modulation is increased and the drive speed of the photosensitive material 12 is brought into a low speed by a speed control signal V5 obtained from the signal processing circuit 7 to attain sharp picture recording. Moreover, when the information signal V3 represents a low gradation number, the photosensitive material 12 is brought into a high speed by the speed control signal V5 to quicken the exposure recording.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention is based on a read signal obtained by optically scanning pixels of characters, figures, images, etc. written on a manuscript, or based on a density signal instructed by a host computer. The present invention relates to an image recording apparatus that records an image by driving a light emitting element and exposing a photosensitive material by the light emitted from the light emitting element. (Prior Art) Various proposals have been made regarding image recording devices such as copying machines and printers. An example of this is to scan an object such as a manuscript while irradiating it with a light source, photoelectrically convert the reflected light to obtain a read signal (image signal), and drive a light emitting element with the read signal. Some devices are configured to expose a photosensitive material to light and record an image written on the document. In the image recording apparatus, in order to record clear images, it is desirable to increase the number of gradations of recording density. As a method of increasing the number of gradations, there are a method of modulating the intensity of light that exposes the photosensitive material, a method of modulating the exposure time, and a method of combining both methods. Here, an example of the conventional modulation will be described with respect to image recording of a JISAJ column. 4 in 10 seconds with the short side of the JISA 4 column as the main scanning direction.
For QQdot/1 nch exposure, when a large polygon mirror is used, the effective exposure time is approximately 1.3 m5ec and 7 lines with a repetition period of about 2m5ec and 7 lines. The time per pixel is a very small time of about 400 nsec/pixel. Taking conventional laser printers as an example, the exposure amount is modulated for each page or line in order to increase the number of gradations, but when trying to modulate each pixel, the following problems arise: There is. (Problem to be solved by the invention) That is, the exposure time per pixel is 400n as described above.
sec/pixel, so if you want to control the intensity of the light emitting element for each pixel, the constant current circuit that drives the light emitting element should be
It must be operated with rise and fall times on the order of nanoseconds, which requires "circuit components" such as special amplifiers with a wide frequency band. However, wideband amplifiers with a fast frequency response are very expensive, and there are various technical problems in manufacturing techniques, which are obstacles to performing modulation on a pixel-by-pixel basis. Further, conventional image recording apparatuses are configured to run on a photosensitive material at a constant running speed regardless of the energy of the exposing light. However, if the object to be read and recorded is text, etc.
Since the contrast is clear, there is no need to increase the number of gradations,
Moreover, even if the traveling speed of the photosensitive material is increased, clear exposure recording can be performed. On the other hand, when the object to be read and recorded is an image consisting of a large number of shades of light and shade, it is desirable to increase the number of gradations in order to express intermediate colors so that clear exposure recording can be performed. The present invention has been devised in view of the above-mentioned problems, and its purpose is to control the traveling speed of the photosensitive material in accordance with the number of gradations of the read signal, without using expensive amplifiers, etc. (Means for Solving Problems) The object of the present invention is to drive a light emitting element and expose a photosensitive material by the light emitted from the light emitting element. In an image recording apparatus that records an image, the first encoded information sets the amount of light emitted by the light emitting element to a predetermined intensity with respect to the density signal obtained in each raw scanning direction, and the light emitting time of each of the above; The information signal includes second information to be controlled corresponding to each pixel, and to obtain an information signal for exposing the photosensitive material with light energy corresponding to the product of the first and second information, and to control the photosensitive material in accordance with the light energy. This is achieved by providing a signal processing circuit that obtains a speed control signal for varying the traveling speed of the material, and a speed control circuit that controls the traveling speed of the photosensitive material in response to the speed control signal. - The density signal obtained in each raw scanning direction is supplied to the signal processing circuit and converted into, for example, a 3-bit encoded information signal.At this time, for example, 2 bits of the 3 bits are determined by the amount of light emitted by the light emitting element. is used as the first information for setting a predetermined intensity, and the other 6 bits are used as second information for controlling the light emission time corresponding to each pixel.As a result, the intensity of the light emitting element can be modulated in 22 ways. Therefore, the light emission time of the light emitting element is modulated in 26 ways.Therefore, the light energy of the light emitting element is intensity-modulated in each of the plural recording main scans for each lifetime scan during reading, and the light emission time is modulated in 26 ways. The light energy can be modulated up to 128 steps by controlling the information signal, and the light emitting element can be driven without using an expensive broadband amplifier.Then, when exposing the photosensitive material, the light energy is modulated in high gradations based on the information signal. When controlled, the traveling speed of the photosensitive material is reduced by the speed control signal and the speed control circuit, and the traveling speed of the photosensitive material is reduced for one sub-scanning (one line pitch).
The recording density is increased to record good images with a large number of gradations. On the other hand, when the light energy is of low gradation, the photosensitive material is run at high speed to reduce the recording density in one sub-scanning range, and high-speed image recording is performed. (Example) Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Note that FIG. 1 is a schematic configuration diagram of an image recording apparatus to which the present invention is applied, and the basic concept of the present invention will first be explained with reference to scanning explanatory diagrams, waveform diagrams, etc. shown in FIG. 2 and subsequent figures. A light source 1 scans a manuscript paper 2 on which characters, figures, images, etc. are written, and a light receiving element 4 receives reflected light 3 corresponding to the presence or absence of the characters, figures, images, etc., as well as shape and density. Namely 1. As shown in FIG. 2, the scanning on the manuscript paper 2 is performed in the sub-scanning direction (Y-direction) after the -scanning in the main-scanning direction (X-direction) is completed, and then in the second main-scanning direction. It performs scanning, and the light receiving element 4 receives reflected light 3 according to the aspect of each pixel A1 to An. The light-receiving element 4 performs a photoelectric conversion operation upon receiving the light, and the current l changes in an analog manner in response to the light l of the reflected light 3. The current-voltage converter 5 obtains a voltage Vl whose level changes in response to the current 1, and the analog-digital converter 6 converts the voltage V1 into a digital signal V2. That is, the read signal is digitized along the path from the light receiving element 4 to the analog-to-digital converter 6. Looking at the voltage V1 and the digital signal V2, the peak value and time width of the voltage V1 are the same as those for each of the pixels A1 to A.
Although it changes as shown in FIG. 3 depending on the aspect of n, it is converted into a digital signal V2. The digital signal V2 is supplied to the memory circuit 8 via the signal processing circuit 7, and is sequentially stored at predetermined addresses. After the digital signal V2 corresponding to, for example, three main scans is stored in the memory circuit 8, the signal processing circuit 7 performs the following signal processing using this as one unit. That is, the energy of the light emitted from the light emitting element 11, which will be described later, is determined by the product of the intensity (light power W) and the light emission time (1), and concentration modulation is performed by controlling either the intensity or the light emission time. be able to. Therefore, the signal processing circuit 7 is configured to obtain an 8-bit information signal V3 for controlling the gradation of recording density from the digital signal v2. The information signal V3 is, for example, V 3 = [:101000
00), the upper two digits correspond to first information that controls the optical power of the light emitting element 11, and the lower six digits correspond to second information that controls the light emission time t. Light emitting element 1
The optical power of 1 corresponds to a current controlled by a constant current circuit 10, which will be described later. Therefore, if there is no pixel information to be recorded in A1 to An, the upper two digits of the information signal V3 are

[00], the light emitting element 11 is not driven. In addition, if there is pixel information to be recorded in the above Al to An and a read signal corresponding to this is obtained, for example, the upper two digits are set to [01] and light is emitted with an optical power of 0.5 mW for the first main scan. Element 11
to drive. That is, in the first main scan,
Regardless of the mode of each pixel, the current is controlled so that the optical power is Q, 5 mW. Furthermore, if the concentration of the read signal is high, the upper two digits are
10], the light emitting element 11 is driven with an optical power of 1 mW, for example. That is, for the second main scan, the current is controlled so that the optical power is 1 mW, regardless of the mode of each pixel. In addition, if the concentration of the read signal is even higher, the upper two digits are set to [11], and the light emitting element 1 is
1. That is, for the third main scan, the current is controlled so that the optical power is 2 mW, regardless of the mode of each pixel. As described above, the upper two digits of the information signal V3 are transmitted to the light emitting element 11.
By setting the signal to control the optical power of 22
In other words, four types of intensity control can be performed: (0031: old) [10] [11].
This is repeated with each recording main scan as one unit. Furthermore, by setting the lower six digits of the information signal V3 as a signal for controlling the light emission time of the light emitting element 11, 26 types of control, that is, 64 types of control can be performed. The light emission time width can be controlled by setting the exposure pulse width of the information signal v3 to, for example, 64 different pulses between 200 nSeC and 400 nSeC. The energy of the light emitted from the light emitting element 11 is
As described above, it is determined by the product of power consumption and light emitting time. Therefore, according to the information signal V3 encoded as described above, a total of 256 steps (gradations) of intensity modulation, that is, recording density Modulation can then be performed. In this embodiment, when there is no pixel in any of AI-An, the upper two digits of the information signal V3 are

Set it to [00] and change the lower 6 digits to all [O]. Therefore, the waveform of the information signal V3 becomes as shown in FIG. 4(A), and in this case, the light emitting element 11 does not emit light and no exposure is performed. In addition, when there is a read signal in A1 to An, the first two digits of the information signal V3 are set to [01], and the light emitting element 11 is set to Q, 5m.
It is driven with an optical power of W, and its light emission time is controlled by the lower six digits. Therefore, the waveform of the information signal V3 becomes as shown in FIG. 4(B), and light is emitted in accordance with the rising time width of the pulse. Furthermore, when the density of the read signal is high, for example, the upper two digits of the information signal V3 are set to [10], and the light emitting element 11 is set to 1 m.
It is driven with an optical power of W, and its light emission time is controlled by the lower six digits. Therefore, the waveform of the information signal V3 is as shown in FIG. 4(C). Further, when the read signal has a high concentration, the upper two digits of the information signal V3 are set to [11], the light emitting element 11 is driven with an optical power of 2 mW, and its light emission time is controlled by the lower six digits. Therefore, the waveform of the information signal V3 is as shown in FIG. 4(D). The information signal V3 controlled as described above is a digital signal.
The signal is supplied to an analog converter 9 and converted into an analog signal v4 corresponding to the information signal V3. As a result, the constant current circuit 10 drives the light emitting element 11 with a current corresponding to the power consumption shown in FIGS. I will do it. By the way, when the light emitting element 11 is driven as described above and sequentially exposed each row with a different optical power, exposure traces tend to appear in the form of horizontal stripes in the main scanning direction. If the information signal V3 has a low number of gradations corresponding to characters, etc., even if the number of scanning lines for intensity modulation is reduced and the travel of the photosensitive material 12 is accelerated, the sharpness of the characters etc. recorded by exposure will not deteriorate. In this case, it is better to shorten the time required for exposure recording to increase recording efficiency. Therefore, when the information signal V3 has a high number of gradations, the number of recording scanning lines to be intensity-modulated is increased, and the traveling speed of the photosensitive material 12 is made low by the speed control signal V5 obtained from the signal processing circuit 7. The information signal V3 of is taken as one unit,
Overlapping exposure is performed in one sub-scanning range of the photosensitive material 12 to record a clear image. Further, when the information signal V3 has a low number of gradations, the speed control signal V5 causes the photosensitive material 12 to travel at high speed, thereby increasing the speed of exposure recording. Looking at an example of speed control of the photosensitive material 12 for exposure recording of a color image, it can be performed as shown in Table 1 in accordance with the amount of information of the information signal V3. Table-1 Information amount Binary (8 colors, 2 pulse widths) 4-value (64 colors, 4 pulse widths) 16-value (4096 colors, 16 pulse widths) 32-value (
32 types of pulse widths) 64 values (329 pulse widths, 2 types of intensities) 128 values (327 pulse widths, 4 types of intensities) 256 values (321 pulse widths, 8 types of intensities) Traveling speed of photosensitive material (7 lines in μm) 63.5 63.5 63.5 63.5 31,8 (1/2) 15,9 (1/4) 7.9 (1/8) The amount of information shown in Table 1 above is for red (R), green (G), Blue (
B) relates to the three primary colors. That is, in the color image recording apparatus, the original 2 is irradiated with the three primary colors to obtain reading signals of the three primary colors. The amount of information indicates the number of gradations of the three primary colors, and as the amount of information (pulse types) increases, a greater number of tones are expressed on the photosensitive material 12. What should be noted in Table 1 above is that photosensitive material 1 up to 32 values
2 is run at 63.5 μm/row, resulting in a high gradation number of 64
The purpose is to sequentially control the running speed per line to 1/2 based on the value. The traveling speed is controlled by lowering the voltage level of the speed control signal V5 obtained from the signal processing circuit 7 to a predetermined level, for example, when the information signal V3 changes from 32 values to 64 values, and the speed control circuit 13 This is done by reducing the rotation of the motor (not shown) of the material supply device 14. The voltage level of the speed control signal V5 is determined by the signal processing circuit 7.
The level decreases as the amount of information increases. As a result, the traveling speed of the photosensitive material 12 increases as the amount of information of the information signal V3 doubles.
It is controlled to decrease by 1/2. By the way, even if the traveling speed of the photosensitive material 120 is lowered as described above, there is a limit to the ability to record a high gradation image by performing only one exposure scan. Therefore, as shown in the characteristics of FIG. 5, the real WI bad mode is that when the information amount of the information signal V3 exceeds a predetermined value, or to explain Table 1 above, when it becomes 32 values or above,
The traveling speed of the photosensitive material 12 is reduced. When the traveling speed of the photosensitive material 12 is controlled to 1/2, exposure scanning is performed twice for one pitch of the photosensitive material 12 as shown in FIG. 6(A), and the light energy per pitch is The exposure recording is made to have a high gradation by increasing the . Further, when the traveling speed of the photosensitive material 12 is controlled to 1/4, exposure scanning is performed four times for one pitch of the photosensitive material 12 as shown in FIG. 6(B), and the light energy per pinch is The exposure recording is made to have a high gradation by increasing the . Further, when the traveling speed of the photosensitive material 12 is controlled to 1/8, exposure scanning is performed eight times for one pitch of the photosensitive material 12, and the light energy per pitch is increased to achieve high gradation of exposure recording. Eggplant. By performing exposure recording as described above, it is possible to perform high-speed exposure for characters with a low number of gradations and a small amount of information, and for images with a high number of gradations and a large amount of information, the characteristics shown in Figure 5 are achieved. As shown, clear exposure recording can be performed by increasing the number of modulations of light energy. Further, in the case of a high number of gradations, since the heavy '01N light is applied for one pitch as described above, the exposure trace does not become striped and a clear image is recorded. Although the basic concept of the present invention has been explained above, the present image recording apparatus includes a color image recording apparatus configured as shown in FIG. 7, and the present invention can be applied to this apparatus. In this case, the same image reading and recording as described above is performed for the three primary colors of red (R), green (G), and blue (B), and an example thereof will be explained with reference to FIG. The A/D converter 21 uses a photoelectric conversion sensor 23 to detect the upper surface of an object 22 such as a document in the horizontal (X direction in the figure) and vertical direction (
Receives an electric signal (image signal) So in pixel units generated by so-called readout scanning in the Y direction),
Each pixel is converted into 3-bit data, for example. Incidentally, since the sensor 23 converts into a signal indicating the gradation of each hue such as R, G, B, etc., the A/D converter 21 converts the digital data DR and DOSDB for each hue.
Output. The line memory 24 temporarily stores a predetermined number of data DR, DG, and DB output from the A/D converter 21. The image processing circuit 25 corresponds to the signal processing circuit described above, and obtains the same encoded information signal as described above based on the data supplied from the line memory 23. The line memory 27, drivers 28, 29, 30, and optical system 31 are recording systems for copying onto a recording medium (such as copy paper) 32 based on the information signal, and the information signal obtained from the image processing circuit 25. The line memory 27 stores a predetermined number (for example, for one horizontal scan) of the data, and outputs the information to a red light emitting driver 28, a blue light emitting driver 29, and a line light emitting driver 30, which are provided in correspondence with each pixel. supply The drivers 28 to 30 drive the light emitting elements (not shown) as described above, and the emitted light is focused by the lenses 33 to 35, and further focused on the same optical axis by the half mirrors 36 to 38. Ru. The reflection mirror 39 changes the path of light, and the rotation of the polygon mirror 40 controls the direction of reflection of the light, that is, the scanning direction, thereby copying, in other words, recording onto the surface of the recording medium 32 (photosensitive material). will be held. During the exposure recording, when the amount of information of the information signal obtained from the image processing circuit 25 becomes large, the speed control signal Vc
level decreases, the speed control circuit 41 reduces the rotational speed of the motor (not shown), and the photosensitive material supply device 42
The traveling speed of the photosensitive material 32 sent out from the is reduced. On the other hand, when the amount of information of the information signal obtained from the image processing circuit 25 becomes small, the level of the speed control signal Vc becomes high. Then, the motor is controlled at high speed by the speed control circuit 41, and the traveling speed of the photosensitive material 320 is increased. Therefore, when recording a color image, the same effect as described with reference to FIG. 1 can be obtained. Although the embodiments of the present invention have been described above, the present invention is not limited to the above, and various modifications are possible. For example, the present invention is not limited to color image recording, but may be applied to monochrome image recording. Further, in the embodiment described above, as the information amount of the information signal doubles, the traveling speed of the photosensitive material is reduced to 1/2, but the present invention is not limited to this ratio. (Effects of the Invention) As described above, according to the present invention, a coded information signal for controlling a predetermined illumination intensity and light emitting time is generated based on an image reading signal obtained by main scanning a document or the like. At the same time, the scanning speed of the photosensitive material is controlled in accordance with the amount of information of the information signal, and the exposure of the sub-scanning range is changed depending on the amount of information. Therefore, the light emitted from the light emitting element is controlled in terms of illumination intensity and light emission time, and since the light energy is set in multiple stages by the product of both, it is possible to increase the gradation when recording images. . Furthermore, since the increase in the number of gradations is performed by changing the time width for each pixel, there is no need to use a wideband amplifier with a fast frequency response, and the cost of the product can be reduced. Further, since the traveling speed of the photosensitive material can be varied in accordance with the information amount of the information signal, in other words, the light energy, the time required for recording can be shortened depending on the form of the image to be exposed and recorded.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of an image recording device to explain the basic concept of the present invention, Fig. 2 is a plan view of the main part to explain scanning on a document, and Fig. 3 is a waveform diagram showing analog-to-digital conversion. , Fig. 4 is a waveform diagram explaining the mode of the encoded information signal, Fig. 5 is a characteristic diagram explaining the traveling speed and exposure situation of the photosensitive material, and Fig. 6 is a diagram explaining the exposure situation of the photosensitive material. FIG. 7 is a schematic diagram of the color image recording apparatus. Reference numeral 1 in the figure...Light source 2...Document 3...Reflected light 4...Light receiving element 5...Current-voltage converter 6...A/D converter 7...Signal processing Circuit 8...Memory circuit 9...D/A converter
DESCRIPTION OF SYMBOLS 10... Constant current circuit 11... Light emitting element for exposure 13... Speed control circuit 14... Photosensitive material supply device V3... Information signal V5... Speed control signal. Go to Figure 3 i, Q ” 1 4th prisoner (A) (D) Transporting Kaiku O○ ○○ ○○ ○tsu■ ■■■の■の■ Procedures 11 Original Book October 1986 Indication of 'F!RIJGO Agency 艮'rI-dono incident 1988 Special revision application No. 2048058 Title of invention Image recording device amendment 16 and matter f1 What relationship: Patent applicant

Claims (1)

[Claims] (1) In an image recording apparatus that drives a light-emitting element and records an image by exposing a photosensitive material using the light emitted from the light-emitting element, the amount of light emitted by the light-emitting element is calculated with respect to the density signal obtained in each main scanning direction. The first encoded information sets the intensity to a predetermined intensity, and the encoded second information controls the light emission time corresponding to each pixel.
a signal processing circuit that obtains an information signal for exposing the photosensitive material with light energy corresponding to the product of information, and obtains a speed control signal for varying the traveling speed of the photosensitive material in accordance with the light energy; An image recording device equipped with a speed control circuit that controls the running of a photosensitive material using control signals.