JPH0331145B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a recording device such as a facsimile,
In particular, the present invention relates to an image recording device using a light emitting element such as a light emitting diode or a light amount control element such as a liquid crystal.

Conventional structure and its problems The level or time width of a drive signal applied to a large number of light emitting elements such as light emitting diodes arranged linearly or in a staggered manner, or a light amount control element such as a liquid crystal, is controlled by an image signal. , records an image corresponding to an image signal by exposing a photosensitive recording medium such as a photosensitive selenium drum with light emitted from each light emitting element or light emitted from a light source with a constant amount of light and transmitted through each light amount control element. Image recording devices are known.

FIG. 1 is a block diagram showing the configuration of an example of the above-described image recording apparatus. In this figure, 11 is a terminal into which image signals are input in series, 12 is an LED (light emitting diode) drive amplifier circuit, 13 is an LED array section, 14 is a scanning clock circuit, 15 is a recording section, 1
6 is a buffer memory. LED array section 13
and the recording section 15 are optically arranged. LED
The drive amplifier circuit 12 is connected to the input terminal 11 via a buffer memory 16 that stores image signals, and also to the scan clock circuit 14 and the LED array section 13.

The LED array section 13 includes an LED array 13a formed by arranging a plurality of LEDs in a linear or staggered manner;
The LED array 13a includes an optical system 13b including an optical lens for condensing the light emitted from the LED array 13a. The recording unit 15 includes a photosensitive selenium drum 15a, which is a photosensitive recording medium, and this drum 1.
A charging section 15b, a developing section 15c, a transfer section 15d, and a cleaning section 15e arranged near the periphery of 5a.
It is made up of etc. The LED drive amplifier circuit 12
It has the same number of amplifiers as the LEDs of the LED array 13a,
It corresponds to each LED. LED array 13a
The LEDs are arranged in the axial direction of the photosensitive selenium drum 15a. The photosensitive selenium drum 15a is rotated in the direction of arrow A by a driving means.

The recording operation of the image recording apparatus shown in FIG. 1 will be explained.

The image signal of the image to be recorded is sent to the terminal 11 in synchronization with the scanning clock generated by the scanning clock circuit 14.
The signals are inputted from each other and stored in the buffer memory 16 in parallel. Each amplifier in the LED drive amplifier circuit 12 applies a drive signal (with a constant time width) based on an image signal to the corresponding LED in synchronization with the scan clock generated by the scan clock circuit 14. For example, when recording a black and white image, the amplifier to which the "black" image signal is input outputs a drive signal of a certain level, and the corresponding
On the other hand, the amplifier to which the "white" image signal is input does not output a drive signal and does not cause the corresponding LED to emit light. LED driven in this way
The light emitted from each LED of the array 13a is sent to the optical system 1.
The photosensitive selenium drum 15a is irradiated via the photosensitive selenium drum 15a. The photosensitive selenium drum 15a has a charging section 5b.
When passing through, it is uniformly charged to a specific polarity,
Next, by being exposed to light from the LED array 13a, an electrostatic latent image corresponding to the image signal is formed. This electrostatic latent image is visualized in the developing section 15c and transferred onto plain paper in the transfer section 15d. This plain paper is sent from the transfer section 15d to the fixing section, where it undergoes a fixing process and becomes a hard copy. On the other hand, transfer section 1
The photosensitive selenium drum 15a that has passed through the photosensitive selenium drum 15d has residual toner removed by a cleaning section 15e, and is then sent to the charging section 15b again.

However, in the above-mentioned image recording apparatus, variations in the characteristics of the light emitting elements or light quantity control elements, unevenness in the quantity of light in the optical system, etc. cause variations in the amount of exposure on the photosensitive recording medium, resulting in uneven recording density. There was a problem that the recorded image quality deteriorated over time.

To solve this problem, the amount of light emitted by each element is measured in advance, light amount correction information is calculated to compensate for variations in exposure amount, and the time of the drive signal for each element is adjusted according to this light amount correction information during recording. One possible method is to correct the width and eliminate variations in the exposure amount for each element.

FIG. 2 is a block diagram of an image recording apparatus based on this idea. In this figure, 23 is a time width correction circuit, and 22 is a buffer memory for storing image signals for one scan. In addition, the code 11,1
2, 13, and 15 correspond to the same reference numerals in FIG. 14 is a scanning clock circuit, which will be described later.
Generates address signals for the ROM (read only memory) and control signals for the buffer memory 22. The ROM 21 stores light intensity correction information for each LED in advance, and the scanning clock circuit 14
As a result, the address corresponding to the LED to be driven is specified, and light amount correction information for the predetermined LED is output to the time width correction circuit 23.

Binary image signals input in series to the input terminal 11 are temporarily stored in a buffer memory 22. When the image signals for one scan are accumulated in the buffer memory 22, the scan clock circuit 14
, the image signals on one scanning line are read out from the buffer memory 22 in parallel for one scanning line, and are inputted in parallel to the time width correction circuit 23 . In synchronization with the reading of this image signal, the scanning clock circuit 14 operates from the ROM.
21 is updated, and light amount correction information for each LED is output from the ROM 21 in parallel for one scanning line.

The time width correction circuit 23 outputs a pulse with a constant time width for all "black" image signals when reading the image signal for the first time, and from the second time onwards, according to the light amount correction information, Outputs a pulse with a narrow constant time width for the “black” image signal. The LED drive amplifier circuit 12 amplifies the pulse from the time width correction circuit 23 and applies it to the corresponding LED as a drive signal.
That is, after outputting a pulse with a fixed time width for the first "black" image signal, each LED is operated a predetermined number of times, and based on the light amount correction information calculated from the total time of the time width of the applied drive signal, By operating each LED a predetermined number of times according to the scanning clock signal,
This is intended to cancel out variations in exposure amount.

In the following, (A) when the number of correction exposures n=1, (B) when the basic exposure time is shorter than the repetition period T, and (C) when the basic exposure time and the repetition period T match will be explained as examples.

(A) When the number of correction exposures is n = 1. Figures 3a and 3b are for each LED.
Shows the light emission amount Li and light amount correction information for each time. Third
Figure c is a waveform diagram of the binary image signal, and Figure 3 d is a waveform diagram of the binary image signal.
FIG. 3 is a waveform diagram of a drive signal for an LED.

During the first exposure of each LED (hereinafter referred to as basic exposure), the time width correction circuit 23 outputs a pulse with a constant time width α for all "black" image signals, as shown in FIG. 3d. like,
LED corresponding to “black” image signal, e.g. i=2,
A drive signal with a time width α is applied to LEDs 3, 4, 5, 8, and 9 (i is a number for identifying the LED). In the second exposure (referred to as the first correction exposure; the same applies to the third and subsequent exposures), "black"
Among the image signals, the value of light intensity correction information Ti is the reference value
A pulse with a fixed time width β (<α) is output only for “black” image signals that correspond to more than 100 LEDs. In this case, as shown in Figure 3d, i=3,
A drive signal with a time width β is applied only to LEDs 5, 6, and 9. In other words, the value of Li is the reference value
The time width α of the drive signal for more than 100 LEDs,
By increasing the time width of the drive signal for the LED whose Li value is less than the reference value 100 by β to α+β, variations in exposure are reduced.

(B) When the basic exposure time is shorter than the repetition period T Figure 4a shows that the basic exposure time is shorter than the repetition period T.
In this case, non-exposure times n ₁ and n ₂ occur between the basic exposure and the first correction exposure and between the first correction exposure and the second correction exposure.

(C) When the basic exposure time and the repetition period T match. Figure 4b shows the case where the basic exposure time and the repetition period T match, and there is a non-exposure period between the first correction exposure and the second correction exposure. n ₃ occurs.

Generally, since the photosensitive recording medium is displaced (rotated, etc.) at a constant speed, the image formation position on the photosensitive recording medium shifts depending on each exposure and the non-exposure time between them. In other words, by correcting the exposure here, a new problem arises in that the shift in the imaging position increases and the image deteriorates.

Purpose of the Invention The present invention eliminates variations in the amount of exposure of a photosensitive recording medium due to variations in the characteristics of light emitting elements or light amount control elements, unevenness in the amount of light in the optical system, etc., and suppresses deviations in the imaging position. An object of the present invention is to provide an image recording device with less image deterioration.

Structure of the Invention The present invention provides an image recording system that includes a plurality of light emitting elements or light amount control elements and an exposure correction means for shortening the non-exposure time between basic exposure and correction exposure of the light emitting elements or light amount control elements. In the apparatus, the exposure correction means has a storage means for storing correction exposure time, etc., and a means for adjusting operating procedures for the correction exposure and the basic exposure based on the information in the storage means and the information on the basic exposure. This is the summary.

Part or all of the correction exposure is performed before the basic exposure, and the timing of exposure is adjusted within each exposure cycle to shorten the non-exposure time.

DESCRIPTION OF THE EMBODIMENTS FIG. 5 is a schematic block diagram of an image recording apparatus according to an embodiment of the present invention. In this figure, 1
1 is a terminal to which image information is input in series; 13 is an LED array section composed of a light emitting diode or the like as a light emitting element or a photoelectric conversion element; 14 is a scanning clock circuit; 15 is a recording section; 21 is a ROM (read-only memory). ), 22 is buffer memory, 23
is a time width correction circuit, 24 is an LED drive amplifier circuit,
31 is a control terminal, and 32 is a strobe signal.

The LED array section 13 and the recording section 15 are optically arranged. The time width correction circuit 23 connects the input terminal 1 via the buffer memory 22 that stores the image signal.
1. It is connected to the LED array unit 13 via the scanning clock circuit 14 and the LED drive amplifier circuit 24, and to the control terminal 31 via the ROM 21. Control terminal 31
inputs and manages information such as the time width correction circuit 23.
It is connected to the CPU and the LED drive amplifier circuit 24 and transmits the strobe signal 32. In the case of this example,
The exposure correction means is composed of an exposure operation procedure adjustment means formed from an LED drive amplifier circuit 24, a time correction circuit 23, etc., and a ROM 21 that is a storage means for corrected exposure time and the like.

The ROM 21 stores light intensity correction information for each LED in advance, and the address corresponding to the LED to be driven is specified by the scanning clock circuit 14.
The light intensity correction information of the predetermined LED is sent to the time width correction circuit 23.
Output to.

A binary image signal input from the terminal 11 is temporarily stored in a buffer memory 22. When the image signal for one scanning line is stored in the buffer memory 22, this signal is read out under the control of the scanning clock circuit 14 and inputted in parallel to the time width correction circuit 23. At this time, the scanning clock circuit 14 updates the address signal of the ROM 21 in synchronization with the reading of the image signal, and each
Light intensity correction information for LED is arranged in parallel for one scanning line
It is output from the ROM 21 to the time width correction circuit 23.

The time width correction circuit 23 adjusts the generation order of basic pulses or pulses having a time width based on the light amount correction information with respect to the "black" image signal in accordance with the clock signal based on the light amount correction information. Also, at this time, the strobe signal 32 is output from the control terminal 31.
It is output to the LED drive amplifier circuit 24 and determines the pulse application timing. The LED drive amplifier circuit 24 amplifies the pulse from the time width correction circuit 23 and applies it to the corresponding LED as a drive signal.
That is, each LED is driven by a predetermined number of circuits, and each LED is
The total time of the pulse width of the drive signal applied to each
Control is performed according to the LED light intensity correction information.

Hereinafter, the operation of the present invention will be explained based on FIGS. 6, 7, and 8. Note that these figures also include figures based on a conventional image recording apparatus for comparison.

FIG. 6 is an exposure characteristic diagram when the time width of the basic exposure _T1 is shorter than the exposure period T and the number of correction exposures is one.

FIG. 6a is an exposure characteristic diagram of a conventional image recording device, in which between the basic exposure T ₁ and the correction exposure T ₂ ,
There is a non-exposure time t ₁ .

FIG. 6b is a characteristic diagram of the image recording apparatus according to the embodiment of the present invention, and shows the characteristics when the application timing of the exposure pulse is controlled. By inputting the strobe signal 32 to the LED drive amplifier circuit 24, the generation position of the basic exposure _T1 is controlled,
Basic exposure is performed so that the exposure end time of basic exposure T ₁ coincides with or is close to the end point of exposure cycle T.
Delay T ₁ exposure start time. As a result, the non-exposure time t ₁ ' becomes 0 or a value close to 0.

FIG. 6c is a characteristic diagram of the image recording apparatus according to the embodiment of the present invention, and in addition to the control shown in FIG. 6b,
This shows the characteristics when the order of exposure pulse generation is controlled. Correction exposure is performed by the time width correction circuit 23.
T ₂ is performed before basic exposure T ₁ , and the strobe signal 32 is input to the LED drive amplifier circuit 24 to control the generation position of correction exposure T ₂ , and the exposure end time of correction exposure T ₂ is Match or approach the end time of period T. As a result, the non-exposure time period t ₁ ″ becomes 0 or a value close to 0.

Figure 7 shows that the time width of basic exposure T ₁ is the exposure period T
FIG. 4 is an exposure characteristic diagram in the case where the correction exposure is shorter than that shown in FIG.

FIG. 7a is a diagram based on a conventional image recording device, in which a non-exposure time t 1 exists between the basic exposure T ₁ and the correction exposure T ₂ , and a non-exposure time t ₁ exists between the correction exposure T ₂ and the correction exposure T ₃ . There is a non-exposure time _t2 .

FIG. 7b is a characteristic diagram based on the image recording apparatus according to the embodiment of the present invention, and shows the characteristics when the application timing and generation order of exposure pulses are controlled. The time width correction circuit 23 performs the correction exposure T ₃ before the basic exposure T ₁ and the strobe signal 32 is input to the LED drive amplifier circuit 24 to control the generation position of the correction exposure T ₃ and perform the correction exposure. By making the exposure end time of T ₃ match or approach the end time of the exposure period T, the non-exposure time t ₂ ' becomes zero or a value close to zero.

FIG. 7c is a characteristic diagram based on the image recording apparatus according to the embodiment of the present invention, and shows control when the order of generation of exposure pulses is changed from the control shown in FIG. 7b. Correction exposure by time width correction circuit 23
By performing T ₂ before the basic exposure T ₁ and inputting the strobe signal 32 to the LED drive amplifier circuit 24, the generation position of the correction exposure T ₂ is controlled,
By making the exposure end time of the correction exposure T ₂ coincide with or close to the end time of the exposure period T,
The non-exposure time t ₂ ″ is set to 0 or a value close to 0.

Figure 8 shows that the time width of basic exposure T ₁ is the exposure period T
FIG. 7 is a characteristic diagram for a case where the correction exposure is shorter than that and three correction exposures are performed.

FIG. 8a is based on a conventional image recording device, between the basic exposure T ₁ and the correction exposure T ₂ , between the correction exposure T ₂ and the correction exposure T ₃ , and also between the correction exposure T ₃
and the correction exposure T ₄ and the non-exposure time t ₁ , respectively.
t ₂ and t ₃ exist.

FIG. 8b is a characteristic diagram of the image recording apparatus according to the embodiment of the present invention, in which the time width correction circuit 23 performs the correction exposure T ₄ before the basic exposure T ₁ , and the strobe signal 32 is transmitted to the LED drive amplifier circuit. 24, the exposure end time of the corrected exposure T ₃ is made to match or approach the end time of the exposure synchronization T, thereby making the non-exposure time t ₃ ' 0 or a value close to 0. Also, instead of correction exposure T ₄ , correction exposure
Similar effects can be obtained by operating T ₃ or T ₂ in the same manner as described above.

Note that the time width correction circuit 23 adjusts the correction exposure T ₃
is taken before the basic exposure _T1 , the characteristic diagram shown in FIG. 8c is obtained.

As described above, as is clear from FIGS. 6, 7, and 8, according to the present invention, the non-exposure time can be set to 0 or a value close to 0. Furthermore, the same effect can be obtained when the correction exposure is performed four or more times. In addition, the time width correction circuit 2 is adjusted so that the required exposure time is minimized.
3. Deterioration in image quality can be minimized by controlling the strobe signal 32.

Note that the same effects as the present invention can be obtained also in the following cases.

(1) We have shown an example of driving an LED for a “black” signal, but when driving an LED for a “white” image signal.

(2) When multiple elements are treated as one block and the average light intensity of each block is corrected.

(3) Although we have shown an example in which each LED to which a drive signal is applied is driven simultaneously, there is a case where each element or each block is driven sequentially.

(4) Although we have shown an example using an LED as a light emitting element,
Instead, the light from the light source is used via a light amount control element such as a liquid crystal.

(5) An image recording device that uses a photosensitive recording medium that directly forms a visible image by exposure to light.

(6) When the basic exposure time width is equal to or longer than the exposure cycle.

Effects of the Invention According to the present invention, the non-exposure time can be set to 0 or a value close to 0, the time required for exposure can be shortened, the deviation of the image formation position on the photosensitive recording medium can be reduced, and the image quality can be improved. It has the effect of

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a conventional image recording device, Fig. 2 is a block diagram of a conventional image recording device, Fig. 3 is an operational characteristic diagram of the image recording device shown in Fig. 2, and Fig. 4 is a conventional image recording device. FIG. 5 is a block diagram of an image recording device according to an embodiment of the present invention; FIG. 6 is a comparison of exposure characteristics between the image recording device shown in FIG. 5 and the image recording device shown in FIG. 2. figure,
7 is a comparison diagram of exposure characteristics between the image recording device shown in FIG. 5 and the image recording device shown in FIG.
The figure is a comparison diagram of exposure characteristics between the image recording apparatus shown in FIG. 5 and the image recording apparatus shown in FIG. 2. 13... LED array section, 13a... LED array, 21...... ROM, 23... time width correction circuit, 24... LED drive amplifier circuit, 31... control terminal, 32... strobe signal.

Claims (1)

[Claims] 1: an LED array section having an LED array and an optical system; a storage means for storing light amount correction information in advance;
Adjustment means that performs basic exposure based on the image signal after the correction exposure based on the light amount correction information, and adjusts the exposure of the LED array section so that the end time of the correction exposure coincides with or approaches the end time of the exposure cycle; and a recording section having a photosensitive selenium drum that rotates at a constant speed while being irradiated with the light output from the adjusting means, and the adjusting means shortens the non-exposure time between the correction exposure and the basic exposure. An image recording device characterized by: