JP3521370B2 - Image forming method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method for forming an image by exposing a silver halide light-sensitive material that moves relatively to a plurality of recording elements arranged in an array.

[0002]

2. Description of the Related Art Among image recording apparatuses for outputting image data, a recording head (hereinafter also referred to as an array head) formed by one row or a plurality of rows of light quantity control type recording elements.
The one using is advantageous in that the structure of the device is simple and compact, and therefore the cost is low.

As a recording head using a light quantity control type recording element, for example, a light source such as an LED array or a fluorescent display tube array (VFPH) which is a light emitting element array is used as a backlight, and an optical shutter array is combined therewith. Examples thereof include PLZT shutter arrays and liquid crystal shutter arrays.

However, since the recording elements constituting the array have variations in light emission characteristics, when used as they are, there is a problem that unevenness in shade occurs in an output image due to uniform data.

For the purpose of correcting the above variations, Japanese Patent Publication No.
JP-A-27443 describes a method in which each recording element is driven by the same signal to record an image, a variation in density of a recorded image is measured to calculate a correction amount, and the correction is performed according to this value. In addition, Japanese Unexamined Patent Publication No. 2-276655
In the publication, a method is proposed in which the above correction is repeated until the shading unevenness is within an allowable range.

However, the above-mentioned correction method is a method for forming an image by temporarily exposing a photoconductor such as a photoconductor drum by an array light source and adhering an image-formed product such as toner to the image-forming member. While the photosensitive member and the image forming body are separate bodies, the positional relationship between the exposing member and the photosensitive member can be fixed, while the above-described correction method is directly exposed to the silver halide photosensitive material which moves relatively to form an image. When it is used for a photosensitive material, since the photosensitive member becomes an image forming body as it is, the positional relationship with the exposure member cannot be fixed exactly, and the shape change, the deflection, the distortion, the vibration, etc., during the transportation of the photosensitive material are prevented. Due to the influence, the obtained correction amount does not contribute to the reduction of the shading unevenness over the entire surface of the light-sensitive material, resulting in the deterioration of the image quality, and making full use of the high image quality characteristics of the silver halide light-sensitive material. Can not, there is a problem.

Further, the above-mentioned correction method is for a photosensitive drum or the like which is supposed to be repeatedly used, and an image is directly formed by post-exposure development such as a silver halide photosensitive material and then exposed again for image formation. In the case where the photosensitive member is used for forming an image on a photosensitive member that is not subject to consideration, it is not considered that the photosensitive member is used up. Therefore, the method for obtaining the correction value for one screen of the photosensitive material is also delicate. However, there is a problem that the effect is small even though the correction becomes complicated by exposure to different photosensitive materials.

Further, according to the above method, there is a case where the correction amount by image formation on the silver halide light-sensitive material is hardly calculated depending on the exposure amount, and the correction amount is converged by repeated calculation. It doesn't hold,
It was also found that there was a problem that it was not possible to reduce the shading.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and the light emission characteristics of each recording element of an array head for forming an image by exposing a silver halide photosensitive material to light. An image forming method capable of stably forming a high-quality image excellent in gradation without unevenness in light and shade by relatively easily correcting the variation of With the goal.

[0010]

According to the present invention, a plurality of recording elements arranged in an array of one column or a plurality of columns of claim 1 moves relative to the recording element. In an image forming method for forming an image by exposing a silver halide light-sensitive material , the number of recording elements is
Exposure with a large or small exposure amount for each recording element
Creating a partial, and measuring the concentration of the silver halide light-sensitive material on different at least image 2 points were form Rikatachi by <br/> the same image data in each recording element, the greater exposure or
Peak position of the density data of the part exposed with a small exposure amount
Or, the valley position is detected, and the detected peak or valley is
The number of recording elements existing between
Obtain the peak position for each recording element and place it at the obtained peak position.
The density of the image formed by the same image data
The light amount data is obtained by measuring, and the correction amount for each recording element for correcting the density unevenness on the silver halide photosensitive material is calculated from the light amount data, and the exposure amount of each recording element is set to the correction amount. The image forming method, which is characterized by the correction based on the above, can prevent the correction using the density data at the peculiar place on the photosensitive material, and is effective in reducing the density unevenness over the entire surface of the photosensitive material. It is possible to easily obtain a certain correction amount, and even when repeatedly obtaining a highly accurate correction amount, the convergence is improved. As a result, a high-quality image with no noticeable density unevenness can be obtained at high speed, and the device can be complicated. It can be formed without increasing the cost and increasing the cost.

An image for forming an image by exposing a silver halide light-sensitive material moving relatively to the recording elements by a plurality of recording elements arranged in an array of one row or a plurality of rows according to claim 2. In the forming method, in the plurality of recording elements , a large exposure amount or a small exposure amount for every several recording elements.
Creating a portion exposed in an amount, and measures the concentration of more formed image the each on the photosensitive material at least two different image data <br/> with each recording element, the greater exposure also
Is the peak position of the density data of the part exposed with a small exposure amount
Position or valley position is detected, and between the detected peaks or valleys,
By dividing at equal intervals by the number of recording elements that exist between them
Obtain the peak position for each recording element, and set the peak position
An image formed by the two different image data in
The light amount data is obtained by measuring the density of the recording amount, and the correction amount for each recording element for reducing the density unevenness on the silver halide photosensitive material is calculated from the light amount data. With the configuration of the image forming method characterized by performing the correction based on the correction amount, it is possible to prevent the correction using the density data at the specific density on the photosensitive material,
It is possible to easily obtain the correction amount that is effective in reducing the uneven density over the entire density of the light-sensitive material, and it is possible to improve the convergence even if an accurate correction amount is repeatedly obtained. It is possible to form an inconspicuous high-quality image at a high speed without complicating the apparatus and increasing the cost.

Further, according to a third aspect of the present invention, each recording element of the array-shaped recording element is exposed to two different points on the silver halide light-sensitive material by exposure with different image data. It is possible to prevent the correction using the density data at each point, and it is possible to easily obtain the correction amount that is effective in reducing the uneven density over the entire surface of the photosensitive material, and as a result, the uneven density can be obtained. An inconspicuous high-quality image can be formed at high speed without complicating the apparatus and increasing the cost.

Further, the density of the image used for calculating the correction amount of each recording element of the array-shaped recording element is set in the linear portion of the characteristic curve of the silver halide photosensitive material. Depending on the configuration, since the part where the gradation characteristics change harder than in the case of higher density or lower density is used, the density difference with respect to the fluctuation of the light amount can be represented greatly and the correction accuracy is improved. To do. Also, 2
Extrapolation and interpolation in the case of calculating the approximate value using the density values above the points can be performed by a linear expression, and the calculation of the correction amount can be simplified.

According to a fifth aspect of the present invention, the correction amount is calculated in a state in which a plurality of recording elements of the array-shaped recording element are driven. Since the amount of light is calculated and corrected while the elements are driven, it is more accurate than when the amount of light is calculated and corrected by illuminating each recording element one point apart from the actual image recording. It becomes possible to correct the variation in the light emission characteristic of the recording element, and thereby it is possible to form a good high-quality image with less uneven density.

Further, while any recording element of the array-shaped recording element of claim 6 is in a driving state, a recording element adjacent to the recording element is set in a non-driving state, and the closest adjacent elements are simultaneously driven during image formation. With a configuration characterized in that the distance to the recording element is the same as the distance to the closest recording element that is driven at the same time when the image used to calculate the correction amount is formed, the condition close to the actual image formation is achieved. It becomes easy to obtain the correction amount accurately, and thus it becomes easy to form a better high quality image.

Further, a plurality of recording elements arranged in an array can be turned on / off independently of each other, and are turned on / off a plurality of times by a combination of the same or different time widths according to image data. Thus, with the structure characterized in that the silver halide light-sensitive material is exposed, it becomes possible to form a multi-tone image with a simple structure. In the formation of an image on a silver halide photographic light-sensitive material by multiple exposures, the discontinuity in the number of multiple-exposure exposures and the discontinuity in light emission time and density caused by the multiple exposure effect of the light-sensitive material cause singular points. Since it becomes easy, the application of the present invention is preferable also in order to eliminate it and obtain smooth gradation.

Further, according to the eighth aspect, a plurality of recording elements in the array form are turned on and off a plurality of times 512 to obtain 512.
With the structure characterized by forming the gradation of not less than 65536 gradations, a uniform image, especially human skin, background sky can be obtained without complicating the apparatus, increasing the cost, and impairing the maximum density. It is possible to obtain a high-quality image with no density unevenness, etc., thereby making it possible to provide an apparatus capable of forming a high-resolution continuous tone image of high quality by utilizing the characteristics of the silver halide photosensitive material. .

Further, the relationship between the density of the image formed by the exposure of the silver halide light-sensitive material and the light amount data is obtained, and the density of the pixel formed by each recording element of the array-shaped recording element is determined from the relationship. Calculate the light intensity data that is the same or the density value when the same light intensity data is given,
Even if the correction density data includes a singular point, the value is not changed even if the correction density data includes a singular point, by the configuration characterized in that the correction amount for each recording element is calculated based on the calculated light amount data or the density value. Since the correction amount is obtained without using it, the correction amount is not calculated as a significantly different value, and it is effective in reducing the unevenness of light and shade in a minute portion.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. However, the present invention is not limited to the embodiments described below.

FIG. 1 is a schematic configuration diagram of an image forming apparatus used for carrying out the method of the present invention. In this apparatus,
A color photographic printing paper (hereinafter referred to as a silver halide photographic light-sensitive material) fed from a roll by a support drum 1 of a conveyance control means rotated by a driving source (not shown).
When 2 is conveyed in the direction of the white arrow,
The red recording head 30a, the green recording head 30b, and the blue recording head 30c, which are provided with recording elements arranged in an array of one row or a plurality of rows, are exposure-controlled by the recording head controller 40 according to image data, and Each color is sequentially exposed at a predetermined position, and a latent image of a color image is formed on the photographic printing paper 2. When the exposure process is completed, the photographic printing paper 2 is conveyed by the support drum 1 to the developing process of the next processing step. An array-shaped light source of one row or a plurality of rows is used for each of the recording heads 30a to 30c, an LED light source that has been generally adopted conventionally is used for the red recording head 30a, and a green recording head 30b and a blue recording head. Thirty
c is a vacuum fluorescent print head (Vac that can be easily separated by a color filter with relatively high brightness and high-speed response).
uum Fluorescent Print Hea
d is hereinafter referred to as VFPH). The photographic printing paper 2 is not limited to the roll shape, and may be cut paper.
The moving means of the photographic printing paper 2 may be other means such as a means for carrying the photographic printing paper 2 on a belt.

The correction processing unit 60 includes recording heads 30a, 30
A correction amount for correcting the light emission characteristics of the recording elements b and 30c is calculated from the density data and output to the printhead control unit 40, and the printhead control unit 40 enables the below-mentioned enable based on the correction amount. Each recording head 3 by controlling the signal
The emission characteristics of 0a, 30b and 30c are adjusted.

FIG. 2 is a drive control circuit block diagram for explaining the image data writing operation of the recording head for one color.
In this figure, the printhead control unit 40 uses 12 for each color.
When the image data representing the gradation by the digital value of the bits is input, the correction process is performed on the image data based on the above-mentioned correction data, and the serial digital image data for one line pixel for each recording element is input. And a set pulse signal for transferring the image bit data to the latch circuit 32 and an enable signal for controlling the light emission time are generated and output to the recording head 30 for one color. Here, the image bit data is specific bit data of the image data.

The recording head 30 includes a recording head controller 40.
From the MSB as image bit data for one line
When the (most significant bit) data is transferred to the shift register 31, the set pulse signal is input to the latch circuit 32, and the MSB data for one line is latched in the latch circuit 32 in synchronization with the set pulse signal. To do. Then, by inputting an enable signal according to the gradation to the driver circuit, drive control is performed for each recording element of the recording elements arranged in an array of one column or a plurality of columns in the time width section of the enable signal and latched. The light is emitted according to the image data. That is, the driver circuit 33 selectively selects the element whose latched data is "1".
A drive signal is sent to 4 and light is emitted for the time width of the enable signal. Irradiation light is SELFOC lens array 3
An image is formed on the photographic printing paper 2 via 5 to form a latent image. By performing such a process sequentially from MSB to LSB (least significant bit) for all bits, recording for one line is completed. The order of bits may start from LSB or may be another order, and is not limited. Although one color has been described above, similar control is performed for all three colors.

VFPH having emission characteristics in green and blue components
In the lower part of the SELFOC lens array 35, green and blue color separation filters (not shown) are arranged, and the recording head control unit 40 conveys the image data transferred for each color. Since the three recording heads 30 perform recording control while sequentially shifting the exposure timing so as to record at a predetermined position on the paper 2, it is possible to perform appropriate color image recording.

FIG. 3 is a detailed block circuit diagram of the printhead control unit 40. The operation of the printhead control unit 40 will be described below.

First, the multiplier 41 corrects the image data by multiplying the image data by the correction data in order to correct the emission characteristic obtained by the correction processing unit 60 described above, and outputs the corrected image data to the interface 42. . The CPU 43 sets a count initial value for counting pixels for one line to the counter 44 via the interface 42 and sets the counter 4
4 is activated, and the demultiplexer 45 for input switching is controlled. In response to this, the counter 44 starts counting and outputs the count value to the demultiplexer 45. Based on the count value, each pixel of the image data is expanded into a density value of 12 bits and processed to 12
Line memory 4 as image data for 1 bit x 1 line
Write to 6.

The line memory 4 for the image data of the first line
6 is completed, the image data of the first line is transferred from the line memory 46 to the multiplexer 48 by M.
The SB to LSB are sequentially output and transferred to the recording head 30. On the other hand, the image data of the second line has its output path switched by the demultiplexer 45 and is written to the line memory 47. As described above, while the image data of the current line is being transferred to the recording head 30, since the image data of the next line is expanded and written in the other line memory, the process is repeatedly performed. The image data of can be continuously output by the expansion process without stagnation in time.

Under the control of the CPU 43, the counter 49 counts the transfer time of the image bit data to the multiplexer 48 and outputs a count-up signal to the set pulse signal generation circuit 50.
0 generates a set pulse signal at the timing when the transfer of the image data to the recording head 30 is finished and outputs it to the recording head 30, and also outputs the set pulse signal to the enable signal generating circuit 52.

On the other hand, under the control of the CPU 43, the counter 51 counts the enable time corresponding to the density value assigned in advance for each 12-bit bit and outputs it to the enable signal generating circuit 52. A reference numeral 52 generates an enable signal having an enable time corresponding to the 12-bit MSB (most significant bit) representing the density value in response to the generation of the set pulse signal, and outputs it to the recording head 30 and also to the CPU 43. Output. Then, the CPU 43 receives this and controls the counter 49 to generate the next set pulse signal.
By repeating such a series of operations, the set pulse signal, the enable signal, and the image bit data are output to the recording head 30 with the timing sequentially taken from MSB to LSB for each line.

FIG. 4 is a timing chart of output signals output from the print head controller 40 to the print head 30b. Of the image data expanded into the density value of 12 bits for each pixel, M of one line is first
After SB is output and transferred to the recording head 30b, a set pulse signal and an enable signal are output. Furthermore, when the latch data for all the enable signals from MSB to LSB, that is, the bit value is “1” and light emission is generated for one recording element, the maximum exposure time is reached and the maximum density is given. . The interval time between enable signals is set to 48 μsec. Similar control is performed for the other recording heads 30a and 30c.

The period of the enable signal for each color at this time is as shown in Table 1.

[0032]

[Table 1]

Further, specific examples in which an image is formed by using the above-mentioned apparatus will be shown below together with comparative examples.

(Experimental Example 1) The images to be formed are the same as those in Examples and Comparative Examples, and an evaluation image A of an image including a close-up of a person's face with a gray gradation background and a density of about 0 on the entire surface of the photosensitive material. As the evaluation image B of a solid image having a uniform density of 0.8, the image quality of those output images is visually evaluated. The correction of the recording head when forming an image is performed by calculating a correction amount based on the following method in each of the comparative example and the example.

Correction Method 1-1: Comparative Example The recording heads 30a, 30b and 30c are respectively corrected by the following procedure, and the evaluation images A and B are output by three-color exposure.

1) An image data value at which the density value on the photographic paper 2 is about 0.8 is obtained by a certain recording element, all the recording elements are caused to emit light by the image data value, and the central portion of the photographic paper 2 is exposed. Then, development processing is performed to obtain an image for correction.

2) The correction image obtained by the above operation is used as a density measuring device (Konica Microdensitometer PDM-5).
(TYPE BR: manufactured by Konica Corporation), density measurement is performed in the recording element array direction of the recording head to obtain density data.

3) FIG. 5 is a partially enlarged view of the graph showing the density data obtained as described above. The density data has a shape in which the density data has a peak at the array position of each recording element, and based on this, the density peak position (i) is detected for each recording element.

4) The numerical data (5 data before and after here) located before and after the peak position (i) obtained above are integrated together with the density data at the peak position, and the integrated density (Di) is obtained.
To calculate. The same is done for all recording elements.

5) The density ratio between the obtained integrated density (Di) and the reference integrated density (avg (D)) (the average value of the integrated density of all measured recording elements) is used as a correction amount (Ci) according to the following formula. It is calculated and stored in the correction memory 66.

Ci = avg (D) / Di 6) Based on the obtained correction amount (Ci), image formation is performed as in the above embodiment.

Correction method 1-2: Example The recording heads 30a, 30b and 30c are corrected by the following procedure, and the evaluation images A and B are output by three-color exposure.

1) An image data value at which the density value on the photographic printing paper 2 is about 0.8 is obtained by a certain printing element, and all the printing elements are caused to emit light by the image data value, and the central portion and the end portions of the printing paper 2 are obtained. Then, the density is measured in the same manner as in the correction method 1-1, and the integrated density and the central integrated density (CD
i) and edge integrated concentration (EDi) are calculated.

2) A correction amount (Ci) is calculated from the obtained integrated densities by the following equation and stored in the correction memory 66.

Ci = avg (D) / ((CDi + EDi) / 2) The reference cumulative concentration (avg (D)) in the above equation is the average value of the cumulative concentrations of the central portion and the end portions.

3) Based on the obtained correction amount (Ci), image formation is performed as in the above embodiment.

As a result, in both of the evaluation images A and B, the embodiment according to the correction method 1-2 does not cause conspicuous unevenness in density in comparison with the comparative example according to the correction method 1-1. , Was able to obtain a good image as a whole.

(Experimental Example 2) The images to be formed are the same as those in the Examples and Comparative Examples, and an evaluation image A of an image including a close-up of a person's face with gray gradation as a background and the entire surface of the photosensitive material have low density. , An evaluation image B of a solid image of medium density and high density, and an evaluation image of giving a wedge image having a gradual density difference on a photosensitive material with a uniform density of several levels in a certain area ranging from low density to high density. As C, the image quality of these output images is visually evaluated. The correction of the recording head when forming an image is performed by calculating a correction amount based on the following method in each of the comparative example and the example.

Correction Method 2-1: Comparative Example Image formation is performed in the same manner as the correction method 1-1 of Experimental Example 1. However, the formed images are the evaluation images A, B, and C.

Correction Method 2-2: Example The recording heads 30a, 30b and 30c are corrected in the following procedure to output the evaluation images A, B and C by three-color exposure.

1) All the recording elements are made to emit light at image data values having density values of about 0.6 and 1.2 on the photographic printing paper 2, and the photographic printing paper 2 is exposed. 1
The respective concentrations are measured in the same manner as in -1, and the respective integrated concentrations D (0.6) i and D (1.2) i are calculated.

2) A correction amount (Ci) is calculated from the obtained integrated densities according to the following equation and stored in the correction memory 66.

Ci = ({avg (D (1.2))-av
g (D (0.6))} / 2 + avg (D (0.6)))
/({D(1.2)i-D(0.6)i}/2+D
(0.6)) Note that avg (D (1.2), avg (D
(0.6)) has a density value of about 1.2 and a density value of about 0.
Measurement of part 6 is the average value of the integrated densities of all recording elements.

3) Based on the obtained correction amount (Ci), image formation is performed as in the above embodiment.

Correction method 2-3: Example The recording heads 30a, 30b and 30c are corrected by the following procedures, and the evaluation images A, B and C are output by three-color exposure.

1) All recording elements have the same image data in the arrangement direction of the recording elements, and in the relative conveyance direction of the photographic printing paper 2, change into a plurality of strips having different density steps at constant widths. A wedge image is formed by illuminating the entire surface of the photosensitive material by emitting light with image data (each density step is about 0.55, 0.7, 0.85, 1.0,
It is formed by performing exposure with image data values of 1.15 and 1.3. ) Is formed, and the respective density measurements are performed in the same manner as in the correction method 1-1 of the first embodiment, and the respective integrated densities D (0.55) i to D (1.3) i are calculated.

2) A linear approximation is performed by the least squares method using the obtained integrated densities and the image data values equivalent to the light amount data, and from the obtained formulas, the approximate integrated densities (RDi) at the light amount data 1.0 are obtained. ) Is calculated.

3) A correction amount (Ci) is calculated from the approximate integrated concentration (RDi) obtained by the above operation by the following formula, and stored in the correction memory 66.

Ci = avg (RD) / RDi In the above equation, avg (RD) is the average value of the approximate integrated densities of all the recording elements measured.

4) Based on the obtained correction value (Ci), image formation is performed as in the above embodiment.

Results In both the evaluation images A and C, compared with the comparative example according to the correction method 2-1, in the example according to the correction method 2-2, there is a density step where density unevenness is particularly noticeable. It was possible to obtain a good image for the wedge as a whole without any generation.

Further, in the embodiment based on the correction method 2-3,
Even when the evaluation images A, B and the evaluation image C were output at any position on the photosensitive material, good images with less unevenness of light and shade could be obtained in all the images.

In the above embodiment, the correction method 1-1, 3).
As shown in, the array position of the recording elements of the recording head was determined by detecting the peak of the density data, but depending on the conveyance accuracy or the mounting accuracy of the recording head,
It may not appear as a clear peak on the concentration data. In that case, the integrated density can be calculated by estimating the position of the recording element by the following method, for example.
As a peak position estimation method in this case, a high density portion is created every few recording elements, and the peak is detected,
There is a method in which the peak position is obtained by dividing the space at equal intervals by the number of recording elements.

Specifically, it can be carried out by the following procedure.

1) From the first recording element, every 50 recording elements are exposed so that the exposure amount is larger than that of other recording elements to obtain a correction image.

2) The peak position of the high density portion on the density data is detected.

3) The high density peaks are divided at equal intervals by the number of recording elements existing therebetween, and the peak position for each recording element is obtained.

4) The recording element exposed with a high exposure amount and the number of recording elements around the recording element cannot accurately calculate the integrated density due to the influence of the high density pixels. Therefore, 50 recordings are separately recorded from the 25th recording element. The same operation as above is performed for each element.

5) Of the both, the portion not affected by the high density pixel is extracted and the integrated density is calculated.

Further, instead of detecting the peak position with an exposure amount larger than that of the other recording element in the above 1), the valley position can be detected with a small exposure amount.

The above method can be used in combination with the method of detecting the peak position of each recording element, if the peak position of each recording element is partially known.

Further, one simultaneous light emitting element is placed for one recording element, and two simultaneous light emitting elements are placed.
It is also possible to improve the peak separability by shifting the light emitting element and outputting a plurality of correction images by setting the recording element, the fourth recording element, or the like.

In this case, the distance to the closest recording element that can be simultaneously driven when actually forming an image and the distance to the closest recording element that can be simultaneously driven when forming a correction amount calculation image. Is preferable from the viewpoint of obtaining the correction amount under the condition close to the actual image forming condition.

The constant value of the image data for correction may be any density at which variations in light and shade can be measured, and is preferably the density in the straight line portion of the characteristic curve of the photosensitive material used, which is the color in the above-mentioned embodiment. Speaking of paper, a density of about 0.5 to 1.5 is preferable.

In the above-mentioned embodiments, the photographic paper (paper for silver halide photographic light-sensitive material) was used for the correction image and the evaluation image, but the silver halide light-sensitive material is not limited to this, and it may be transparent or semi-transparent. Such as transparent photographic paper, negative film, reversal film, reversal paper, photosensitive material sensitive to visible to infrared wavelengths, monochrome photosensitive material for X-ray photography, photosensitive material having self-processing liquid (instant photosensitive material), etc. Any photosensitive material that can form a visible image,
The same effect can be obtained by using an apparatus that performs exposure with a light source having an appropriate wavelength.

The light-sensitive material for the correction image and the light-sensitive material actually used for image formation may be different, but the same light-sensitive material is used in that correction is possible including the characteristics of the light-sensitive material. It is preferable.

In the above-mentioned embodiment, the Konica Microdensitometer PDM-5T is used as a device for measuring the concentration.
Although YPE BR (manufactured by Konica Corporation) was used, the same evaluation was performed using various scanners such as a commercially available flat bed scanner and drum scanner, and it was possible to obtain substantially the same effect.

In the above embodiment, the interval between adjacent light emitting recording elements in the recording element array direction and the data sampling interval in the density measuring device are about 85 μm (300 d), respectively.
pi recording head) and 5 μm, the ratio of the former to the latter is preferably 4 to 200 from the viewpoint of accuracy and workability for calculating the correction amount.

Further, in the above-mentioned embodiment, the average value of all the recording elements is used as the reference integrated density, but the maximum value or the minimum value in all the recording elements may be used as the reference.

It is also possible to improve the correction accuracy by performing correction using the correction value obtained as necessary, outputting the correction image, and further obtaining the correction value by the same method. is there.

In the above-mentioned embodiment, an example of correction by only density measurement is given, but brightness measurement by an appropriate photometric device may be used in combination. Further, the density measuring means and the brightness measuring means may be incorporated in the image forming apparatus, or the correction value may be calculated externally without being incorporated and stored in the memory for use.

In the above-mentioned embodiment, the correction is based on the multiplication of the correction values, but the correction method is not limited to this, and the same effect can be obtained by the correction by addition, subtraction and division.

In the above embodiment, the LED recording head, V
Although the FPH recording head is used, the recording head for exposure is not limited to this, and P using a suitable backlight is used.
LZT recording heads, optical shutter arrays such as liquid crystal shutter array recording heads, laser array recording heads in which semiconductor lasers are arranged in an array, etc. have multiple recording elements, and each recording element can be driven independently on / off. The same effect can be obtained by using the above recording head.

In the above embodiment, the photosensitive material is moved with respect to the recording element to form an image, but the recording element may be moved with respect to the photosensitive material to form an image.

Further, although the gradation control method in the above-mentioned embodiment is the exposure time modulation by a plurality of exposures, it may be a single exposure by a brightness modulation, an exposure time modulation or the like, or a combination of both, and is not limited. is not. In particular, in the method of controlling the exposure time by multiple exposures in general, in the uniform image data part, different image data is obtained depending on the correction coefficient, so uneven density occurs due to different exposure times of multiple exposures, Even if it is repeatedly corrected, it may not converge to a desired level without shading unevenness. However, by applying the present invention to that, it is possible to reduce the effect and to converge to a level without shading unevenness. ,preferable.
In particular, when the number of gradations is 512 or more, the uneven density is remarkably reduced without impairing the maximum density. Further, by setting the number of gradations to 65536 or less, simplification of the apparatus and improvement in processing speed can be achieved. Since it can be achieved, it is preferable that the number of gradations by multiple exposures is 512 gradations or more and 65536 gradations or less.

6 and 7 show another example of the image forming apparatus for carrying out the method of the present invention described above.
Among them, in the apparatus of FIG. 6, the light of a single light source 3 which is turned on during image formation is split by an optical fiber 36 and guided to PLZT recording heads 37a, 37b, 37c with a color filter, and the recording heads 37a, 37b, 37c. Paper of silver halide photosensitive material conveyed by a pinching conveying roller by means of
The red, green and blue recording heads 3 of the image forming apparatus of FIG.
The same exposure as 0a, 30b, and 30c is performed to obtain the same effect. Therefore, the correction for each printing element is P
This is performed for each element of the LZT recording heads 37a, 37b, 37c.

In the apparatus shown in FIG. 7, the head carrier 38 having the small width recording heads 38a, 38b and 38c for red, green and blue is mounted on the conveying screw 5 driven by the motor 4.
By moving in the width direction with
8a, 38b and 38c are used to perform a large exposure over the entire width of the printing paper 2 so that a high quality image similar to that of the image forming apparatus of FIGS. 1 and 6 can be formed. Are narrow print heads 38a, 38b,
Each recording element 38c is carried out in the same manner as in each recording element of the recording heads 30a, 30b, 30c of FIG. 1 regardless of the position of the head carrier 38, or it can be changed depending on the position of the head carrier 38. The correction amount is separately obtained depending on the position of the head carrier 38, and the correction amount is calculated based on the correction amount.

[0088]

As described in detail above, according to the image forming method of the present invention, the light emitting characteristics of the respective recording elements of the array head for forming an image by exposing the silver halide photosensitive material to each other are relatively uniform. It is possible to easily correct and form a high-quality image with excellent gradation and without unevenness in density, stably.
It is possible to obtain a remarkable effect that the device is not complicated.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an example of an image forming apparatus used for carrying out a method of the present invention.

FIG. 2 is a drive control circuit block diagram illustrating an image data writing operation of a recording head for one color.

FIG. 3 is a detailed block circuit diagram of a recording head controller.

FIG. 4 is a timing chart of output signals output from the print head control unit to the print head.

FIG. 5 is a density data graph in which all recording elements of the recording head are made to emit light at predetermined image data values and recorded on photographic paper.

FIG. 6 is a schematic configuration diagram showing another example of an image forming apparatus used for carrying out the method of the present invention.

FIG. 7 is a schematic configuration diagram showing another example of an image forming apparatus used for carrying out the method of the present invention.

[Explanation of symbols]

1 Support drum 2 photographic paper 3 light sources 30 recording head 30a red recording head 30b green recording head 30c blue recording head 31 shift register 32 Latch circuit 33 Driver circuit 37a, 37b, 37c PLZT recording head 38a, 38b, 38c narrow print head 40 recording head controller 52 Enable Signal Generation Circuit 60 Correction processing unit

Front Page Continuation (72) Inventor Atsushi Takei, Konica Co., Ltd. 1 Sakura-cho, Hino-shi, Tokyo (56) References JP-A-7-61049 (JP, A) JP-A-2-36962 (JP, A) JP-A-6-143682 (JP, A) JP-A-2-71222 (JP, A) JP-A-1-176572 (JP, A) JP-A-6-270471 (JP, A) JP-A-6-127025 (JP, A) JP-A-5-94068 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/44 B41J 2/45 B41J 2/455 G03B 27/32 H04N 1 / 036

Claims (9)

(57) [Claims] 1. An image forming method for forming an image by exposing a silver halide light-sensitive material moving relative to a recording element by a plurality of recording elements arranged in an array of one row or a plurality of rows, in the plurality of recording elements, the number recorded
A unit that exposes a large amount of light or a small amount of light for each element
In each recording element , and at least two different points on the silver halide light-sensitive material are recorded by the same image data in each recording element.
The density of the image was measured with form Rikatachi, the greater the exposure amount or a small
The peak position of the density data of the part exposed with a short exposure amount or
Detects the valley position, and between the detected peaks or valleys,
Each item is divided by dividing the number of recording elements existing between them at equal intervals.
Obtain the peak position for each recording element and place it at the obtained peak position.
The density of the image formed by the same image data
The light amount data is obtained by setting the light amount data, and the correction amount for each recording element for correcting the density unevenness on the silver halide photosensitive material is calculated from the light amount data, and the exposure amount of each recording element is set to the correction amount. An image forming method characterized by performing correction based on the above. 2. An image forming method for forming an image by exposing a silver halide light-sensitive material moving relatively to the recording elements by a plurality of recording elements arranged in an array of one row or a plurality of rows, in the plurality of recording elements, the number recorded
A unit that exposes a large amount of light or a small amount of light for each element
Creating a minute, and the respectively on the photosensitive material is more formed in at least two different image data for each recording element
The density of the image is measured, and the large or small exposure amount
The peak position or the valley position of the density data of the part exposed by
Detected, existing between the detected peaks or valleys
By dividing the recording element at equal intervals by the number of recording elements
The peak position is calculated, and the two at the calculated peak position
The density of the image formed by different image data of
The light amount data is obtained by calculating the correction amount for each recording element for reducing the density unevenness on the silver halide photosensitive material from the light amount data, and the exposure amount of each recording element is calculated based on the correction amount. An image forming method characterized by correction. 3. The image forming method according to claim 2, wherein two different points on the photosensitive material are exposed. 4. The density is set in a straight line portion of a characteristic curve of the photosensitive material.
3. The image forming method described in 3. 5. The correction amount is calculated in a state in which a plurality of the plurality of recording elements are driven.
5. The image forming method according to any one of 4 above. 6. A recording element adjacent to the recording element is set to a non-driving state while any recording element of the plurality of recording elements is in a driving state, and even the nearest recording element driven simultaneously at the time of image formation. 6. The image forming method according to claim 5, wherein the distance between the first recording element and the closest recording element that is driven at the same time when the image used to calculate the correction amount is the same. 7. The silver halide sensitization method is such that the plurality of recording elements can be independently turned on and off, and are turned on and off a plurality of times by a combination of the same or different time widths according to image data. The image forming method according to claim 2, wherein an image is formed by exposing the material to light. 8. The light amount of the exposure is 512 gradations or more and 655
The image forming method according to claim 7, wherein the number of gradations is 36 or less. 9. The relationship between the density of the silver halide light-sensitive material and the light quantity data is obtained, and the light quantity data or the same light quantity data that gives the same density to the pixels formed by each recording element is given from the relationship. 9. The image forming method according to claim 2, wherein a density value at time is calculated, and the correction amount is calculated based on the calculated light amount data or the density value.