JPH0433188B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image signal correction device, and in particular, in a flat scanning photoelectric transmitter/receiver device using a vibrating mirror, recording caused by non-uniform velocity of a recording light spot. The present invention relates to an image signal correction device that corrects image distortion.

[Prior art]

In general, in a flat scanning photoelectric transmitter/receiver that uses a vibrating mirror, if the vibration speed of the vibrating mirror is constant during scanning, the scanning speed of the recording light spot that scans the photosensitive recording medium is slower in the center and slower in the periphery. It is well known that it is faster. Therefore, if the pixel data for each pixel read from the original image by constant speed scanning is recorded as is, the above-mentioned characteristics will cause distortion in which the periphery of the recorded image in the main scanning direction is more expansive than the central area.

An image signal correction device in a conventional photoelectric transmitting/receiving device using a vibrating mirror adds data for correcting the above-mentioned non-uniform velocity to the driving power of the vibrating mirror, and variably controls the vibration speed of the vibrating mirror during scanning. The scanning speed of the recording light spot is corrected to be constant.

[Problem that the invention seeks to solve]

However, with the conventional method described above, it is difficult to create complete data, and when the vibration speed of the vibrating mirror increases, variable speed control becomes physically difficult and complete correction becomes impossible. There is a problem in that density unevenness parallel to the sub-scanning direction occurs in some recorded images.

An object of the present invention is to prevent the occurrence of density unevenness and easily create complete correction data by changing the temporal position of each pixel data in inverse proportion to the time change in the scanning speed of the recording light spot. An object of the present invention is to provide an image signal correction device.

[Means for solving problems]

The image signal correction device of the present invention includes a planar scanning type recording optical system including a light source and a vibrating mirror, and a system that reads out pixel data corresponding to a preceding scanning line while writing pixel data corresponding to a subsequent scanning line. A first storage means having a capacity for storing the pixel data corresponding to two scanning lines, and a recording light spot from the recording optical system due to non-uniform velocity at the recording scanning part during the preparation period prior to scanning. In order to cancel the positional error of each of the recording light spots corresponding to each of the pixel data, correction data for controlling the readout timing of each of the pixel data to the first storage means is written, and the correction data is used to a second storage means for reading pixel data and sequentially updating the correction data based on the readout result to create modified correction data;
and third storage means provided in parallel with the storage means for storing the modified correction data and controlling the readout timing of the pixel data with the modified correction data during recording scanning.

[Effect]

In the present invention, during an adjustment period prior to scanning, pixel data corresponding to one scanning line is stored in a RAM serving as a second storage means, and the position of the recording light spot for each scanning line is Correction data for each pixel data that cancels out the error is written from a keyboard or the like, and the read timing is controlled by the correction data to read out the pixel data for each scanning line stored in the first storage means, and based on the readout result. By sequentially updating the correction data to correct values, the data stored in the second storage means is made into complete corrected correction data. The non-uniform velocity of the vibrating mirror can be corrected by writing the correction correction data into the ROM as the third storage means, reading the correction correction data from the ROM during recording scanning, and controlling the read timing for the first storage means. The object of the present invention is to realize an image signal correction device that prevents the occurrence of density unevenness in recorded images due to the above-mentioned problems.

As a result, it is possible to write the final complete data to the ROM, which is difficult to rewrite. First, the correction data written to the second storage means is rough, and then the correction data is written according to the recording measurement results. All you have to do is modify the details. Therefore, initial adjustment is easy, adjustment man-hours can be shortened, and complete correction data can be obtained.
It has the advantage of being stored in ROM.

〔Example〕

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

FIG. 1 is a block diagram showing an embodiment of the present invention, in which the image signal correction device includes an A/D conversion circuit 1, a first
A storage section 2 as a storage means, a frequency divider 3, a write counter 4, a read counter 5, a variable frequency divider 6, a RAM 7 as a second storage means, and a ROM 8 as a third storage means. , an inversion circuit 9 , a write/read control circuit 10 , a D/A conversion circuit 11 , a recording circuit 12 , and a recording section 13 .

The operation of the embodiment shown in FIG. 1 will be explained below.
This will be explained in detail with reference to FIGS. 2 and 3.
2 is a perspective view of a main part of the recording section 13 in FIG. 1, and FIG. 3 is a time chart for explaining the operation of the storage section 2 in FIG. 1.

In FIG. 1, the pixel signal D _A is a series of input signals for each pixel having a voltage value corresponding to each pixel density, and is supplied to the A/D conversion circuit 1 and converted into a multilevel code according to each voltage value. pixel data di.

The storage unit 2 includes switchers 21, 23, 24 and 2.
6, and RAMs 22 and 25. RAM
Each of 22 and 25 has a capacity capable of storing pixel data di corresponding to one scanning line, and one repeats writing and reading alternately, such that while one is writing, the other is reading.

The write/read control circuit 10 switches switches 21 and 23 and switches 24 and 24 at each rise of the phase signal P.
A write/read instruction signal E and are supplied to each of 26 and 26 respectively. The write/read instruction signal E is a signal in which when one is “high”, the other becomes “low”,
The RAMs 22 and 25 are instructed to write when the write/read instruction signal E is "high" and to read when the write/read instruction signal E is "low".

The synchronous clock _S1 has a period n times the pixel period, and the pixel clock _S2 is divided by 1/n by the frequency divider 3.
is supplied to the write counter 4.

The write/read control circuit 10 outputs a counter activation signal F which becomes "high" every time the inverted phase signal rises and becomes "low" every time the next inverted phase signal falls.
is generated, and the write counter 4 and read counter 5
supply to.

The write counter 4 counts the pixel clock _S2 while the counter activation signal F is "high" to generate a write address WE, and is set to the initial value when it becomes "low".

During the period when the write/read instruction signal E is "high", pixel data di corresponding to the m-th scanning line is supplied from the switch 21 to the RAM 22. On the other hand, the write address WE is supplied from the switch 23 to the RAM 22, and according to the instruction of the write address WE,
Pixel data di corresponding to the m-th scanning line of the RAM 22 is written.

The write/read instruction signal becomes "high" with the phase signal P for the (m+1)th scanning line, the switchers 24 and 26 enter the writing state, and the (m+1)th scanning line is written to the RAM 25 in the same manner as above. Corresponding pixel data di is written.

On the other hand, pixel data di corresponding to the m-th scanning line
While writing the data into the RAM 22, the write/read instruction signal is "low" and the switches 24 and 26 are in the read state.

Here, prior to explaining the read operation of the RAMs 22 and 25, the recording section 13 shown in FIG. 2 will be described.

As shown in FIG. 2, the recording section 13 includes a recording optical system 14, a pair of feed rollers 16 and 17, and a recording medium 15.

The recording optical system 14 includes a light source 141 such as a helium/neon laser, an optical modulator 142, a slit plate 143, a lens 144, and a vibrating mirror 145.

The laser beam from the light source 141 is transmitted to the optical modulator 14
2, passes through the slit of the slit plate 143, and becomes recording light of a predetermined size at the lens 144. The recording light from the lens 144 is sent to the vibrating mirror 145.
, and forms a recording light spot on the recording scanning portion 18 of the recording medium 15 .

The optical modulator 142 is, for example, an AO modulator that utilizes an acousto-optic effect, and deflects the laser beam according to the voltage value of the recording signal D′ _R from the recording circuit 12. Therefore, when the recording signal D' _R has a voltage value corresponding to black, the laser beam from the optical modulator 142 passes through the entire surface of the slit of the slit plate 143, and when the recording signal D'R has a voltage value corresponding to white, it passes through the slit plate 143. By setting the deflection amount of the optical modulator 142 so that it does not pass through the slit, the recording scanning portion 18
The light intensity of the upper recording light spot can be modulated according to the voltage value of the recording signal D' _R .

The vibrating mirror 145 vibrates by a predetermined angle in one direction at a main scanning speed and returns to the initial position at a high return speed in the opposite direction, repeating the vibration, and main-scans the recording light from the lens 144 from the initial position B of the recording scanning part 18. Main scanning movement is performed within the range of end position C.

The recording medium 15 is flat, and therefore, when the vibration speed of the vibrating mirror in the main scanning direction is set constant, the speed of the recording light spot moving on the recording scanning part 18 is slower in the center and moves toward the periphery. It gets faster as the time increases. Therefore, if an image signal read at a constant speed is recorded as it is, a distortion will occur in the recorded image that spreads from side to side.

The recording medium 15 is held between a pair of feed rollers 16 and 17, and is moved in the sub-scanning direction A at a sub-scanning speed to perform printing scanning.

Next, referring to FIG.
The read operation of No. 5 will be explained.

During initial adjustment prior to recording an image signal, a pulse signal of a constant period synchronized with the pixel clock _S2 is supplied from the recording circuit 12 to the recording section 13, and the recording section 13 creates a record on the recording medium 15. Correction data that changes the frequency division ratio of the variable frequency divider 6, which measures the line spacing parallel to the sub-scanning direction of the recorded image and controls the read timing of the read counter 5 so that the difference between the respective line spacings becomes zero. is written into the RAM 7 for each pixel data corresponding to one scanning line.

When writing to the RAM 7, correction data is input to the terminal 71 from, for example, a keyboard, a "low" write enable signal H is input from the terminal 72, and a "low" read enable signal K is input from the terminal 73. At this time, the inversion read enable signal for the ROM 8 becomes "high" in the inversion circuit 9, and reading from the ROM 8 is not performed.

The variable frequency divider 6 changes the frequency division ratio of the separately supplied synchronous clock S ₁ in accordance with the correction data from the RAM 7 and supplies the read clock S ₃ to the read counter 5 . Therefore, the frequency division ratio of the variable frequency divider 6 is 1/n
In this case, the read timing of the read address RE supplied from the read counter 5 to the RAMs 22 and 25 is the same as that of the write address WE.

The read counter 5 counts the read clock _S3 while the counter activation signal F is "high" to generate a read address RE, and is set to the initial value when it becomes "low".

A pulse signal synchronized with the above-mentioned pixel clock _S2 is supplied to the A/D conversion circuit 1, and the encoded pulse signals are sequentially written into the RAMs 22 and 25 using the above-described writing method. First, writing is performed to RAM 22, and then, while writing to RAM 25, RAM 22 becomes in a read state.

Now, pixel data d1, ~, dN corresponding to each of the 1st to Nth pixels in the main scanning direction
Assume that the correction data for the first pixel data d1 is (n+3). Read address RE for pixel data d1 is RAM2
At the same time that the pixel data d1 is read out, it is also supplied to the RAM 7, and (n+3) correction data is supplied from the RAM 7 to the variable frequency divider 6.

The variable frequency divider 6 has a frequency division ratio of 1/(n+3), generates a read clock _S3 by dividing the frequency of the synchronous clock _S1 by 1/(n+3), and supplies it to the read counter 5. The read counter 5 counts the read clock _S3 ,
A read address RE for the second pixel data d2 is generated, and the pixel data d2 is read from the RAM 22.

If the correction data for the second pixel data d2 is (n+2), the read address RE for the pixel data d2 is supplied to the RAM 7 (n+2).
The correction data is supplied from the RAM 7 to the variable frequency divider 6. Therefore, the variable frequency divider 6 is 1/(n+2)
The frequency division ratio becomes ₁ /(n+
2) The frequency-divided read clock _S3 is supplied to the read counter 5. The read counter 5 counts the read clock _S3 and determines the read address for the pixel data d3.
Generate RE and read pixel data d3 from RAM22. At the same time, correction data for the pixel data d3 is read from the RAM 7.

Thereafter, the process proceeds in the same way to obtain the Nth pixel data dN.
The read addresses RE up to this point are sequentially generated at read timings according to the correction data, and reading from the RAM 22 is completed.

Each pixel data di corresponding to the encoded pulse signal read out from the RAM 22 is supplied to the D/A conversion circuit 11.

The D/A conversion circuit 11 converts the modified multi-level encoded pulse signal into a voltage value corresponding to each pixel data and outputs a recording signal D _R.
After amplifying the signal, the signal is supplied to the recording section 13 and recorded.

Next, the write/read instruction signal E becomes "high" with the phase signal P, and the inverted write/read instruction signal E becomes "low".
Then, the pixel data di corresponding to the encoded pulse signal corresponding to one scanning line written in the RAM 25 is read out and recorded in the same manner as above.

The above operation is repeated multiple times, the line spacing parallel to the sub-scanning direction of the resulting recorded image is measured, the correction value of the correction data is determined based on the measurement result, and the terminal 71
The correction data is corrected by writing it to RAM7. By repeating this correction, corrected correction data that can completely correct the position error is stored in the RAM 7.

Next, connect the RAM to the external ROM writer from terminal 74.
After supplying the modified correction data of No. 7 and writing the modified correction data into the ROM 8, the ROM 8 is installed in a predetermined position and the terminals 71, 72, 73 and 74 are set to high impedance to complete the initial adjustment.

An example of the above write/read timing relationship is shown in FIG.

That is, the pixel clock _S2 for writing is generated every five clocks of the synchronizing clock _S1 , and the corresponding read clock _S3 generates three pixel data in four clocks S of the synchronizing clock _S1 in the order of pixel data.
This is the timing relationship between write pixel data and read pixel data for each pixel data when 5 clocks correspond to 2 pixel data and 6 clocks correspond to 3 pixel data.

Next, when recording and scanning, as mentioned above, the RAM
Pixel data di for each scanning line is sequentially written into 22 and 25. In addition, the terminal 72 is set to high impedance, and the read enable OE of ROM8 is set to high impedance.
is "low", the read enable OE of RAM7 becomes "high", and ROM8 enters the read state.

In this state, similar to the reading of the correction data from the RAM 7 described above, the modified correction data is read from the ROM 8 for each read address RE for the pixel data di, and the frequency division ratio of the variable frequency divider 6 is adjusted to the modified correction data. The timing of generation of the read address RE from the read counter 5 is controlled accordingly.

Therefore, the recording signal from the D/A conversion circuit 11
D _R has a time array in which the positional error of each pixel data due to the non-uniformity of the vibrating mirror 145 is corrected, and no distortion occurs in the recorded image reproduced in the storage unit 13.

〔Effect of the invention〕

As described above, the image signal correction device of the present invention includes a RAM as the first storage means and a RAM as the second storage means.
and by adding ROM as a third storage means,
The correction data is sequentially updated in advance in the second storage means to create complete correction correction data, the obtained correction correction data is stored in the third storage means, and the pixel data stored in the first storage means is By controlling the readout timing of each pixel with the corresponding correction correction data, complete correction correction data can be created extremely easily. It changes in inverse proportion to the change in , and it is possible to prevent density unevenness from occurring in the recorded image, which has the effect of reducing the number of adjustment steps and improving the image quality.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention;
2 is a perspective view of a main part of the recording section in FIG. 1, and FIG. 3 is a time chart for explaining the operation of the storage section in FIG. 1. In the figure, 2...Storage unit, 5...Read counter, 6...Variable frequency divider, 7, 22, 25...
RAM, 8...ROM, 13...recording section, 14...
...recording optical system.

Claims (1)

[Claims] 1. A planar scanning type recording optical system including a light source and a vibrating mirror, and a recording optical system corresponding to at least two scanning lines for reading out pixel data corresponding to a preceding scanning line while writing pixel data corresponding to a subsequent scanning line. a first storage means having a capacity to store pixel data;
During the preparation period prior to scanning, the first recording light spot is configured to cancel the positional error of each of the recording light spots corresponding to each of the pixel data due to non-uniform velocity of the recording light spot from the recording optical system in the recording scanning region.
Write respective correction data for controlling the readout timing of each of the pixel data into the storage means, read out the pixel data with the correction data, update the correction data sequentially based on the readout result, and create modified correction data. a second storage means for creating the pixel data, and a second storage means for storing the modified correction data provided in parallel in the second storage means, and controlling the readout timing of the pixel data with the modified correction data during recording scanning. 3. An image signal modifying device comprising: