JP4477392B2 - Exposure apparatus and light amount correction method for exposure apparatus - Google Patents

Description

  The present invention relates to an exposure apparatus that outputs an image using a light-emitting pixel array composed of a plurality of light-emitting pixels, and more particularly to an exposure apparatus including a correction unit that corrects variations in the amount of light between the light-emitting pixels and a light amount correction method thereof. .

  2. Description of the Related Art Conventionally, an optical printer that forms a color image by performing light exposure on a color photosensitive material or the like using an exposure head having a plurality of light emitting pixels is known. Since such an exposure head has a plurality of light emitting pixels, there is a disadvantage that a variation in the amount of light by each light emitting pixel occurs due to various factors and a good image cannot be obtained. For this reason, it has been proposed to perform shading correction (light amount correction) by measuring variations in the light amount of each light emitting pixel (see, for example, Patent Document 1). A conventional optical printer head will be described below with reference to the drawings.

  FIG. 7 is a light emission pixel array of an optical printer head using a conventional fluorescent light emitting tube, a light amount characteristic diagram output from the light emission pixel column, and a light amount characteristic diagram as a result of performing a conventional shading correction. In FIG. 7, 1 is an optical printer head using a fluorescent light emitting tube, and 2 and 3 are first and second light emitting pixel columns. The light emitting pixel rows 2 and 3 are constituted by a plurality of substantially square light emitting pixels 2a to 2c and 3a to 3c, and are arranged in a staggered manner as shown in the figure. Note that the total number of light emitting pixels in the light emitting pixel columns 2 and 3 is actually composed of several hundreds or more, but is shown here with a small number of pixels for convenience of explanation. The fluorescent arc tube has an anode substrate, a cathode, a phosphor layer, etc., which are omitted here.

  4 is a light amount graph showing variations in the amount of light output from the light emitting pixel columns 2 and 3, and shows an example of variations in the amount of light output from the light emitting pixels 2a to 2c and 3a to 3c. Here, the light amount graph 4 varies for each luminescent pixel as shown in the figure due to various factors, but it is understood that the light amount near both ends of the optical printer head 1 is considerably lower than the light amount near the center. I can do it. Although the main cause is not shown in the drawing, both ends of the filament-shaped cathode inside the fluorescent light emitting tube are welded and fixed to the metal fitting, and the heat of the cathode is taken away by the metal fitting so that the vicinity of both ends of the cathode This is due to the fact that the temperature of the substrate does not reach a sufficient temperature for electron emission.

  Here, when an image is exposed to a silver salt instant film or the like as a color photosensitive material using the above-described optical printer head having a variation in the amount of light, a uniform image can be obtained due to uneven density in the image. Absent. For this reason, it is necessary to measure shading correction by measuring the variation in the amount of light of each light emitting pixel. Specifically, all the light-emitting pixels are turned on under the same conditions, the light output is measured, and correction information for each light-emitting pixel is calculated based on the measured light amount so that the light amounts of all the light-emitting pixels are constant. Based on the correction information, the light quantity of each light emitting pixel is adjusted by controlling the lighting time, for example.

  According to this light amount correction method, the light amount is corrected in accordance with the light amount of the light emitting pixel having the lowest light amount among the light emitting pixels 2a to 2c and 3a to 3c. The light amount is set to the light amount level A of the light amount 4a at the left end of the graph. Here, the reason for correcting for light emitting pixels with low light intensity is to increase the lighting time of the light emitting pixels with low light intensity or to apply high voltage to the fluorescent tube to correct for light emitting pixels with high light intensity. This is because it is not preferable because an increase in exposure time (that is, printing time) and an increase in exposure energy occur.

  However, if correction is made in accordance with the light emitting pixel having the lowest light amount, the light amount is considerably reduced near both ends of the optical printer head 1 as described above, and the entire light amount correction is performed in accordance with the low light amount level near both ends. In this case, even if the variation in the amount of light is improved, the amount of light necessary for exposure cannot be obtained, and the entire printed image tends to become dark, so that a good image cannot be obtained. Further, when the voltage applied to the fluorescent tube is increased in order to improve the darkness of the image, as a result, there arises a problem that exposure energy is lost more than necessary by performing light amount correction.

  For this reason, in Patent Document 1, as a measure for improving the above problem, a predetermined number of pixels (that is, the light emitting pixels 2a, 2b, 3a, and 3b) in the vicinity of both ends of the light emitting pixel rows 2 and 3 in which the amount of light decreases is set as an invalid area. A light emitting pixel other than the region (that is, the light emitting pixels 2c and 3c) is set as an effective region, and the light amount when the same condition is lit is measured for the light emitting pixels 2c and 3c which are the effective regions, and the effective region is based on the measured light amount. The correction information for the light emitting pixels 2c and 3c is calculated so that the light quantity of the light emitting pixels becomes constant. Based on the correction information, the light amount of the light emitting pixels 2c and 3c is corrected by controlling the lighting time, and the light amount correction is not performed for the light emitting pixels 2a, 2b, 3a and 3b in the invalid area. Has proposed. According to this light amount correction method, exposure correction is performed with reference to the light amount 4b, which is the lowest light amount in the effective region, so that the reference level is the light amount level B. Here, in the light quantity level A based on the light quantity 4a and the light quantity level B based on the light quantity 4b, the light quantity at the light quantity level B is clearly higher as shown in the figure. The image is less likely to become dark and the exposure energy loss is small.

  Although not shown, an optical printer head that exposes and stores an image on a color photosensitive material using a liquid crystal shutter (hereinafter abbreviated as LCS) having a line-like pixel row and a RGB light emitting diode (hereinafter abbreviated as LED) as a line light source. Has also been proposed. Even in the optical printer head using the LCS, there is a variation in the amount of light for each pixel due to various factors. There is a problem that uneven density occurs.

  Here, the change in the light modulation characteristics is due to the structure of the LCS, and the vicinity of both ends of the pixel column is close to the sealing material which is one of the constituent members of the LCS, and impurities and uncured resin of the sealing material are aligned in the LCS. It is considered that the main factor is that the film and the liquid crystal material are adversely affected, and as a result, the response characteristics near both ends of the pixel column change with respect to the response characteristics near the center of the pixel column of LCS. That is, FIG. 8 is a response characteristic diagram in LCS, in which the horizontal axis indicates the drive gradation and the vertical axis indicates the response integrated light quantity. In FIG. 8, Ta is a response characteristic of almost the entire pixel including the central portion of the LCS, and Tb is a response characteristic of pixels near both ends of the pixel column of the LCS. The response characteristic Tb is worse than the response characteristic Ta due to the influence of the sealing material described above, so that the response integral signal decreases with respect to the same gradation signal, and as a result, when shading correction is performed, Correct correction reference values cannot be obtained from the pixels near both ends of the pixel column. Therefore, even in an optical printer head using LCS, shading correction based on pixels in an effective area (pixels with response characteristics Ta) excluding pixels near both ends of the pixel column is necessary.

Japanese Patent No. 3444229 (Claims, Fig. 5)

However, the light quantity correction of the optical printer head described above corrects the light quantity uniformly within the effective area where the light quantity correction is performed, but since the light quantity correction is not performed in the invalid area, the effective area and the invalid area are particularly important. In the vicinity of the boundary, the change in the amount of light remarkably occurs, and density unevenness occurs at both ends of the printed image, so that a good image cannot be obtained. That is, 5 in FIG. 7 is a light amount graph as a result of correcting the light amount by matching the effective region with the light amount 4b, but as shown in the drawing, the light amount in the effective region is corrected to the light amount level B and is uniform. The amount of light in the invalid area on the left and right of the graph 5 has the same variation as the light amount graph 4 before the light amount correction because the light amount is not corrected. In particular, there is a light amount step or a large light amount change near the boundary between the effective region and the invalid region. And uneven density tends to increase rather.

  The light quantity graph 5 is the data after the light quantity correction in the optical printer head using the fluorescent light emitting tube. Even in the optical printer head using the LCS, if the same correction is performed, the effective area and the invalid area are displayed. In the vicinity of the boundary, a difference in the amount of light or a large change in the amount of light occurs. Further, as a means for correcting the difference between the response characteristics near the center of the LCS and the response characteristics near both ends, the difference between the response characteristics near the center of the LCS and the vicinity of both ends is examined, and the data of the difference between the response characteristics is A method of correcting shading by changing the correction coefficients near and both ends is conceivable. However, in this correction method, in the manufacturing process of an optical printer head using LCS, it is necessary to measure the response characteristics of each LCS near the center and near both ends, calculate the correction coefficient, and determine the correction data. In addition, it is not a good idea because the number of measurement steps and inspection adjustment steps in the manufacturing process increases and the cost of the exposure apparatus increases significantly.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and in an exposure head light amount correction, to correct the light amount variation of the entire area to be exposed, to improve density unevenness due to the light amount variation, and to obtain an excellent image. It is to provide a light amount correction method.

  In order to solve the above-mentioned problems, the exposure apparatus of the present invention and its light quantity correction method employ the following configurations and methods.

  The exposure apparatus of the present invention supplies gradation data by supplying image data to a light-emitting pixel column composed of a plurality of light-emitting pixels, and measures each light-emitting pixel obtained by measuring the light-emission output of the light-emitting pixel column. In an exposure apparatus that performs light amount correction to make the light amount of each light emitting pixel uniform according to correction data, a predetermined number of light emitting pixel regions from both ends of the light emitting pixel column are excluded pixel regions, and other pixel regions Is used as a target pixel region, and light amount correction is performed using correction data created based on the light emission output of the target light-emitting pixel that constitutes the target pixel region, and the exclusion light-emitting pixel that constitutes the exclusion pixel region includes the target The correction data that is the same as that of a specific light emitting pixel of the light emitting pixel is supplied.

  With the exposure apparatus of the present invention, even in the excluded pixel region, the light amount correction is performed with the correction data of the specific light emitting pixel in the target pixel region, so that the light amount correction can be realized in all the pixel regions including the excluded pixel region, and the density A good image with little unevenness and good appearance can be printed.

  The correction data supplied to the excluded light emission pixels by the exposure apparatus of the present invention is the same correction data as the target light emission pixels at both ends of the target pixel region.

  As a result, since the excluded pixel region performs light amount correction with the same correction data as the target light emitting pixels at both ends of the target pixel region, the light amount correction can be realized while maintaining the continuity between the excluded pixel region and the target pixel region. The density unevenness near the boundary between the excluded pixel area and the target pixel area is reduced, and a good-looking image including the print peripheral part can be printed.

The light amount correction method of the exposure apparatus of the present invention is obtained by measuring a light emission output of the light emitting pixel row, having a light emitting pixel row composed of a plurality of light emitting pixels for performing gradation exposure using supplied image data. In the light amount correction method of the exposure apparatus for performing light amount correction for making the light amount of each light emitting pixel uniform by the correction data for each light emitting pixel, a predetermined number of light emitting pixel regions are defined from both ends of the light emitting pixel column. Correction data is created based on the light emission output of the target light-emitting pixel that constitutes the target pixel area, with the other pixel area as the target pixel area, and the correction data is used to determine the target light-emitting pixel. While performing light quantity correction, the same correction data as the specific light emission pixel of the said target light emission pixel is supplied to the exclusion light emission pixel which comprises the said exclusion pixel area | region.

  With the light amount correction method of the exposure apparatus of the present invention, light amount correction is performed with correction data of a specific light emitting pixel in the target pixel region even in the excluded pixel region, so light amount correction is performed in all pixel regions including the excluded pixel region. It is possible to print a good image with good density and low density unevenness.

  The correction data supplied to the excluded light emission pixels by the light amount correction method of the present invention is the same correction data as the target light emission pixels at both ends of the target pixel region.

  With this light quantity correction method, the excluded pixel area performs light quantity correction with the same correction data as the target light emitting pixels at both ends of the target pixel area, so light quantity correction can be realized while maintaining the continuity between the excluded pixel area and the target pixel area. As a result, density unevenness near the boundary between the excluded pixel region and the target pixel region is reduced, and a good-looking image including the print peripheral portion can be printed.

  As described above, according to the present invention, even in the excluded pixel region, the light amount correction is performed with the correction data of the specific light emitting pixel in the target pixel region, so that the light amount correction can be realized in all the pixel regions including the excluded pixel region. Therefore, it is possible to provide an exposure apparatus that prints a good image with little density unevenness and good appearance.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a circuit block diagram of an exposure apparatus of the present invention. FIG. 2 is an LCS pixel array of the exposure apparatus of the present invention, a light amount characteristic diagram output from the LCS pixel column, and a light amount characteristic diagram as a result of performing shading correction. FIG. 3 is a block diagram showing a configuration of a measurement system that performs light quantity measurement for performing shading correction in the exposure apparatus of the present invention. FIG. 4 is a flowchart of light quantity measurement for performing shading correction of the exposure apparatus of the present invention. FIG. 5 is a flowchart for obtaining correction data for performing shading correction of the exposure apparatus of the present invention. FIG. 6 is a correction data table showing an example of correction data for performing shading correction.

  The circuit configuration of the exposure apparatus of the present invention will be described with reference to FIG. Reference numeral 10 denotes an exposure apparatus according to the present invention, which includes an exposure head 20 and an exposure control circuit 30. 21 of the exposure head 20 is an LCS having a line-like pixel row (see later), and 28 is a plurality of LEDs having red, green and blue emission colors. The output light from the LED 28 is irradiated to the pixel column of the LCS 21 as a line light source by a light guide plate (not shown), and the output light light-modulated by the pixel column passes through a lens array (not shown). Through a photosensitive material such as a silver salt instant film (not shown).

The exposure control circuit 30 includes an input interface circuit (hereinafter abbreviated as input I / F) 31 for inputting image data P1 from an external personal computer (not shown) or the like, and shading correction (light amount correction) for the image data P1. ) To generate corrected image data P2, a correction data memory 33 for storing correction data P3 for shading correction, an exposure correction circuit 34 for generating exposure timing data P4 from the image data P1, and a corrected image The LCS control circuit 35 that receives the data P2 and the exposure timing data P4 and generates the LCS control signal P5, the look-up table (hereinafter abbreviated as LUT) 36 for generating the LCS control signal P5, and the LCS control signal P5 The LCS drive signal P6 for driving each pixel of the LCS 21 is output. An LED drive control circuit 37, an LED drive condition memory 38 for storing LED drive condition data P7, an LED lighting control circuit for generating an LED drive signal P8 for driving the LED 28 in accordance with the exposure timing data P4 and the LED drive condition data P7 39, an output interface circuit (hereinafter abbreviated as output I / F) 40 for outputting the LCS drive signal P6 and the LED drive signal P8 to the LCS 21 and the LED 28 of the exposure head 20. It is assumed that shading correction correction data P3 and LED drive condition data P7, which will be described later, are stored in advance in the correction data memory 33 and the LED drive condition memory 38, respectively.

  Next, the LCS pixel array of the exposure head 20 of the exposure apparatus 10 of the present invention and the light quantity distribution characteristic output from the LCS will be described with reference to FIG. In FIG. 2, 21 is a simplified illustration of the LCS built in the exposure head 20 described above. The LCS 21 has a structure in which two glass substrates 22a and 22b are bonded to each other through a slight gap. Transparent electrodes (not shown) are formed on the glass substrates 22a and 22b, and the glass substrates 22a and 22b are further formed. A liquid crystal material (not shown) is sealed in the gap. Reference numeral 23 denotes a line-shaped pixel column as a light emitting pixel column formed by the transparent electrode, and the pixel column 23 is constituted by a plurality of substantially rectangular pixels 24 as light emitting pixels. Note that the shape of the pixel 24 is not limited, and may be, for example, a substantially parallelogram inclined at a predetermined angle, or the staggered arrangement described above.

  Further, since the portion other than the pixel column 23 is covered with a light shielding film (not shown) made of a chromium material or the like, only the plurality of pixels 24 that block the light and form the pixel column 23 in the portion other than the pixel column 23. Has a structure that transmits light. Then, the output light from the LED 28 that passes through the plurality of pixels 24 is transmitted or blocked according to the driving voltage applied to the transparent electrodes formed on the glass substrates 22a and 22b by the encapsulated liquid crystal material. Therefore, as a result, the LCS 21 has a function as an optical shutter that optically modulates the transmitted light in accordance with the LCS drive signal P6. Note that a drive IC that applies a drive voltage to the transparent electrode is generally mounted on the glass substrate 22a or 22b of the LCS 21, but is omitted here. Further, in this embodiment, the number of pixels 24 forming the pixel array 23 is 480 for printing a VGA size image, and the pixel pitch is 100 μm. The number of pixels is small. Further, the number of pixels and the pixel pitch may be arbitrarily determined according to the specifications of the exposure apparatus.

  25 is a light amount graph showing an example of a light amount distribution output from the pixels 24 when all the pixels 24 of the pixel row 23 of the LCS 21 are driven under the same conditions. As is apparent from the light amount graph 25, the light amount output from each pixel 24 varies, and this light amount variation varies for each exposure head due to various factors. Here, a decrease in the amount of light and a large change in the amount of light are observed near the left and right ends of the light amount graph 25. The main causes of this are as described above, the variation in the light amount distribution characteristics of the line light source by the LEDs 28, and the pixel array of the LCS 21. This is considered to be a decrease in the amount of light due to the vicinity of both ends of a lens array (not shown) arranged in a line arranged corresponding to 23, a change in response characteristics near both ends of the pixel column, and the like. In order to easily understand the effect of the shading correction of the present invention, the light amount variation (light amount graph 4) of the optical printer head shown as the conventional example and the light amount variation (light amount graph 25) of the exposure apparatus of the present invention are the same. Presented on the assumption.

  The main object of the present invention is to reduce the density unevenness of the photosensitive material caused by the light quantity variation as seen in the light quantity graph 25, and particularly to reduce the density unevenness near both ends of the pixel column. Reference numeral 26 denotes a light amount graph showing an example in which shading correction (light amount correction) is performed according to the present invention to reduce the light amount variation, but a detailed description thereof will be given later. Hereinafter, a measurement system that acquires correction data for shading correction and an actual shading correction method will be described.

  A configuration of a measurement system that acquires correction data for performing shading correction by the exposure apparatus of the present invention will be described with reference to FIG. In FIG. 3, the measurement system includes the exposure apparatus 10, measurement apparatus 50, and control personal computer (hereinafter abbreviated as PC) 80, which are measurement objects. Although not shown, the exposure apparatus 10 is attached to the measurement apparatus 50 by an attachment, and the exposure apparatus 10 and the measurement apparatus 50 are electrically connected by signal lines P10 and P11. The measuring device 50 and the PC 80 are connected by a bus line P12.

  The measuring apparatus 50 includes an exposure apparatus interface circuit (hereinafter abbreviated as exposure apparatus I / F) 51, a current supply circuit 52, a PC interface circuit (hereinafter abbreviated as PC-I / F) 53, a drive condition signal creation means 60, and a light quantity measurement. Means 70 are provided. The drive condition signal creating means 60 includes a CPU 61 that controls the entire measurement apparatus 50, an LCS drive circuit 62 that drives and controls the LCS 21 of the exposure apparatus 10 via the exposure apparatus I / F 51 and the signal line P10, and a drive condition of the LED 28. LED driving condition memory 63 for storing data, LCS driving condition memory 64 for storing driving condition data for measuring the LCS 21 built in the exposure head 20, and illuminance F (N) of each pixel of the LCS 21 A light amount memory 65 for storing (see below), and a correction data memory 66 for storing correction data for correcting the light amount variation of each pixel of the LCS 21.

  The CPU 61 is connected to the PC 80 via the PC-I / F 53 and the bus line P12, and inputs control data such as measurement start timing, measurement end timing, and driving conditions of the exposure head 20 from the PC 80, and exposure is performed using the control data. The head 20 and the whole measuring apparatus 50 are controlled to measure the light emission output from the exposure head 20. The current supply circuit 52 supplies a drive current to the LED 28 built in the exposure head 20 via the exposure apparatus I / F 51 and the signal line P11, and changes the supplied current value to emit light from the LED 28. Control strength.

  The light quantity measuring means 70 includes a CCD line sensor 71, a CCD control circuit 72 for controlling the CCD line sensor 71, and a received light amount detection circuit for detecting each received light amount of a plurality of light receiving elements of the CCD line sensor 71. 73, an integration circuit 74 for integrating the detection output of the received light amount detection circuit 73 to obtain received light amount data per predetermined time. The CCD line sensor 71 has a plurality of light receiving elements (not shown) arranged in a line, and the light receiving length is set to be longer than the length of the pixel row 23 of the LCS 21. The total number of light receiving elements is 2048, and the pitch width of the light receiving elements is 25 μm. Although not shown, the measuring device 50 includes a ROM that stores a control program for the CPU 61, a RAM that temporarily stores various data, and the like.

  The measuring device 50 and the PC 80 obtain the LED drive condition data of the LED 28 of the exposure head 20 and the correction data of the LCS 21 according to the measurement procedure described later, and temporarily store them in the LED drive condition memory 63 and the correction data memory 66. The PC 80 outputs a storage control signal P13, and the LED driving condition data and the correction data temporarily stored in the measuring apparatus 50 are stored in the LED driving condition memory 38 and the correction data memory 33 of the exposure control circuit 30 of the exposure apparatus 10. The exposure apparatus 10 that can be transferred and stored to perform appropriate LED driving and shading correction is manufactured.

Next, the determination of the applied current value to the LED 28 and the measurement of the light emission output from each pixel 24 of the LCS 21 executed by the measurement system shown in FIG. 3 will be described based on FIG. First, when measuring the amount of light, the exposure head 20 is set at a predetermined location of the measuring apparatus 50, and a measurement start instruction is transmitted from the PC 80 to the CPU 61 of the measuring apparatus 50 via the bus line P12 to start the measurement operation.

  In FIG. 4, the CPU 61 of the measuring apparatus 50 supplies a predetermined reference LED current value to the LED 28 of the exposure head 20 via the current supply circuit 52, and the LED 28 is lit (ST1). Here, as described above, the LED 28 is composed of LEDs having a plurality of emission colors of red, green, and blue, and the amount of light of each pixel 24 is measured for each emission color. Is supplied and lights up. The CPU 61 controls the LCS drive circuit 62 and drives all the pixels 24 of the LCS 21 under the same conditions. For example, if the LCS 21 is driven with an 8-bit gradation signal and the gradation range is 0 to 255, all the pixels 24 may be driven with the intermediate gradation 128.

  Next, the CCD line sensor 71 inputs a line-like light emission output from the pixel row 23 of the LCS 21 and outputs a light reception signal. The received light amount detection circuit 73 detects the received light signal from the CCD line sensor 71, the integrating circuit 74 integrates the detected received light signal for a certain period, and converts it into a digital signal by an A / D conversion circuit (not shown), and then receives the light receiving element. Each light amount data E (X) is input to the CPU 61 (ST2). As described above, since the CCD line sensor 71 has 2048 light receiving elements, 2048 light quantity data E (X) (X is 0 to 2047) are acquired.

  Here, as described above, since the pixel pitch of the pixels 24 of the LCS 21 is 100 μm and the pitch of the light receiving elements of the CCD line sensor 71 is 25 μm, there are four light receiving elements for the light emission output from one pixel 24. Will be in charge. Further, as shown in FIG. 2, the pixel row 23 of the LCS 21 has a gap (usually about 25 μm) between the pixels, so that light does not pass through this portion and the amount of light decreases. Therefore, the light amount data E (X) from the CCD line sensor 71 includes data (valley part) in which the light amount value decreases for every four data according to the pitch of the pixels 24.

  Next, the CPU 61 obtains a maximum light amount value Emax of the input light amount data E (X) (ST3). Next, the CPU 61 determines whether or not the maximum light amount value Emax is included in a predetermined range. If the determination is affirmative, the process proceeds to flow ST6, and if the determination is negative, the process proceeds to flow ST5 (ST4). This is because the output value of the A / D conversion circuit may be saturated if the light quantity maximum value Emax is too large, and if it is too small, the light quantity data E (X) is compressed and a good measurement result is obtained. Because you can't. In the present embodiment, the maximum light amount value Emax is set to be 90% or less and 80% or more of the conversion limit of the A / D conversion circuit as an example.

  Next, if a negative determination is made in the flow ST4, the reference LED current value applied in the flow ST1 is changed by a predetermined proportional amount, and the flows ST2 to ST4 are executed again (ST5). Here, the predetermined proportional amount is 10% in the present embodiment. When the maximum light amount Emax is higher than a predetermined range, the current is reduced by 10%, and when it is low, the current is increased by 10%. The LED current value is changed by the supply circuit 52.

  Next, if an affirmative determination is made in flow ST4, the CPU 61 detects and stores the valley V (N) where the light amount value is reduced from the light amount data E (X) (ST6). Here, as described above, the valley portion V (N) is generated when the amount of light decreases due to the gap between the pixels of the LCS 21. By detecting the valley portion V (N), each of the pixels 24 of the LCS 21 is detected. The position can be determined. N is a serial number indicating the position of each valley, and is an integer of 0 and 1 or more.

Next, the CPU 61 detects the largest light amount data between the adjacent valley V (N) and valley (N + 1) and stores it as a peak value P (N) (ST7). The CPU 61 also acquires and stores the light receiving element number Xp of the CCD line sensor 71 that detected the peak value P (N) together with the peak value P (N).

  Next, the CPU 61 calculates and stores an adjacent change amount R (N) that is a change amount between the valley portion V (N) and the adjacent peak value P (N) (ST8). The adjacent change amount R (N) is a change amount between the valley portion V (N) and the adjacent peak value P (N), and then the valley value V (N + 1) adjacent to the peak value P (N). The amount of change between and is obtained. In addition, the polarity of the adjacent change amount R (N) increases in the direction from the valley V (N) to the adjacent peak value P (N) (+), and from the peak value P (N) to the adjacent valley V (N + 1). ) Is stored as (−).

  Next, the CPU 61 detects the maximum increase amount Rmax and the maximum decrease amount Rmin from the stored adjacent change amount R (N), and stores the positions (ST9).

  Next, the CPU 61 recognizes and stores the area between the maximum increase amount Rmax and the maximum decrease amount Rmin as a pixel area where the pixel row 23 of the LCS 21 exists (ST10).

  Next, the CPU 61 stores a predetermined number of pixel regions at both ends of the obtained pixel region (that is, the width of the pixel column 23 of the LCS 21) as an excluded pixel region and stores the remaining pixel region as a target pixel region (ST11). . Here, in this embodiment, the number of excluded pixels constituting the excluded pixel region is assumed to be 5 pixels. An example of the excluded pixel area and the target pixel area is indicated by LCS 21 in FIG. 2, and if the position of the leftmost pixel in the pixel row 23 is N = 0, the excluded pixel area exists at both ends of the entire pixel area. The pixel positions of the excluded pixels are N = 0 to 4 and N = 475 to 479, and the pixel positions of the target pixels constituting the target pixel region are N = 5 to 474.

  Next, the CPU 61 stores the stored peak value P (N) in the target pixel region as the illuminance F (N) of the Nth pixel 24 of the LCS 21 (ST12). That is, the peak value P (N) is stored as the amount of light from each pixel 24. In actuality, the peak value P (N) is measured with some amount of light from adjacent pixels, and is not necessarily accurate illuminance from individual pixels. Let value P (N) = illuminance F (N).

  Next, the CPU 61 detects and stores the minimum light amount Fmin in the illuminance F (N) in the target pixel region (N = 5 to 474) (ST13).

  Next, the CPU 61 determines whether or not the minimum light amount Fmin is within a predetermined light amount range. If the determination is affirmative, the process proceeds to the next flow ST17, and if the determination is negative, the process proceeds to flow ST15 (ST14).

  Next, if a negative determination is made in flow ST14, the CPU 61 changes the current value currently applied to the LED 28 to a current value changed by a predetermined proportional amount (for example, 5%), and the newly changed current value. The value is supplied to the LED 28 by controlling the current supply circuit 52 (ST15). Here, as an example, when the minimum light amount Fmin is smaller than a predetermined range, the LED current is changed by + 5%, and when it is larger, it is changed by -5%.

Next, as in the above-described flow ST2, the CCD line sensor 71 inputs the line-like light emission output from the pixel row 23 of the LCS 21, re-acquires the light amount data E (X), and inputs it to the CPU 61 (ST16). . Next, after re-acquisition of the light amount data E (X), the steps ST6 to ST16 are repeated, and the LED current value is adjusted so that the minimum light amount Fmin falls within a predetermined light amount range. If the minimum light amount Fmin is extremely low, dust or the like may be attached to the pixel 24 of the LCS 21 or the LED 28 may be broken. Therefore, the adjustment flow of the minimum light amount Fmin is not executed and the exposure head 20 is not used. A non-defective product is preferable.

  Next, if an affirmative determination is made in flow ST14, the CPU 61 stores the current LED current value in the LED drive condition memory 63, and at the same time, stores data related to the current drive time for each pixel 24 of the LCS 21 in the LCS drive condition. (ST17).

  Next, the CPU 61 stores the current illuminance F (N) in the light amount memory 65 for shading correction described later (ST18). Thus, the determination of the value of the current applied to the LED 28 and the measurement of the light amount of the light emission output from each pixel 24 of the LCS 21 are completed.

  Next, acquisition of correction data for shading correction of the exposure apparatus of the present invention will be described based on the flowchart of FIG. Here, the flowchart shown in FIG. 5 may be executed in accordance with the system control software stored in the PC 80 of the measurement system while the PC 80 and the CPU 61 of the measurement apparatus 50 cooperate with each other, or the PC 80 alone. However, it is assumed here that the PC 80 is executed alone as an example. In FIG. 5, first, the PC 80 prepares a relational expression T (H) between the drive gradation (H) common to all the pixels 24 of the LCS 21 and the standardized irradiation exposure amount T (ST21). . The relational expression T (H) will be described later.

  Next, the PC 80 reads the illuminance F (N) of the target pixel area stored in the light quantity memory 65 of the measuring apparatus 50 (ST22).

  Next, the PC 80 detects the minimum light amount Fmin from the illuminance F (N) (ST23).

  Next, the PC 80 sets N = 5, and selects the first pixel in the target pixel area (the leftmost pixel in the target pixel area in FIG. 2) (ST24).

Next, the PC 80 obtains a corrected reference value U (N) for the Nth pixel based on the detected minimum light amount Fmin (ST25). Here, the correction reference value U (N) can be obtained from the following equation.
U (N) = Fmin · F (N)
The correction reference value of the pixel corresponding to the minimum light amount Fmin is 1.00.

  Next, the PC 80 sets the drive gradation level H to H = 0 (ST26). Here, the drive gradation level H is a level at which the LCS 21 is gradation driven. In this embodiment, the drive gradation level H is an 8-bit gradation drive, and thus the drive gradation level H ranges from 0 to 255.

Next, the PC 80 calculates the irradiation exposure amount S (H) required when the driving gradation level H is input for the Nth pixel from the correction reference value U (N) and the relational expression T (H) as follows: (ST27).
S (H) = T (H) / U (N)

Next, the PC 80 obtains a real value H ′ that satisfies S (H) = T (H ′) for the Nth pixel (ST28). Here, H 'is required for when given as a drive gradation level N-th pixel, obtaining the same irradiation exposure with the case of driving the gradation level H to the pixel is given to the minimum light amount Fmin The drive gradation level is represented. That is, when the driving gradation level H is given to the Nth pixel, the shading correction is performed by changing H to H ′.

  Next, the PC 80 rounds off the decimal point of H ′ to obtain correction data H ″ that is an integer value (ST29). This is because the system including the exposure head 20 in this embodiment is as described above. This is because gradation driving is performed by 8 bits and only an integer of driving gradation levels of 0 to 255 can be handled.

  Next, the PC 80 stores the correction data H ″ in the correction data memory 66 of the measuring apparatus 50 (ST30).

  Thereafter, the PC 80 repeats the same processing for all drive gradation levels (H = 0 to 255) for the Nth pixel (ST27 to ST31 and ST33). Further, the same processing is repeated for all target pixel regions (N = 5 to 474) (ST25 to ST34).

  Next, the PC 80 reads the correction data H ″ of the pixels at both ends of the target pixel area stored in the correction data memory 66 of the measuring device 50 at flow ST30 (ST35). N = 474, and correction data H ″ for this pixel is read out. When correction data H ″ is stored in the PC 80, the correction data H ″ may be used.

  Next, the PC 80 stores the read correction data H ″ of N = 5 pixels in the correction data memory 66 as correction data for the excluded pixel region (N = 0 to 4). Further, the PC 80 is read. Further, the correction data H ″ of the pixel of N = 474 is stored in the correction data memory 66 as the correction data of the excluded pixel region (N = 475 to 479) (ST36). That is, the correction data of the excluded pixel region (N = 0 to 4) is the same as the correction data of the leftmost pixel (N = 5) of the target pixel region adjacent to the excluded pixel region, and the excluded pixel region (N = The correction data of 475 to 479) is the same as the correction data of the rightmost pixel (N = 474) of the target pixel area adjacent to the excluded pixel area. Next, the PC 80 reads the correction data H ″ for all the pixel regions (that is, N = 0 to 479) from the correction data memory 66 of the measuring apparatus 50 and stores it as correction data P3 in the correction data memory 33 of the exposure apparatus 10. Further, the LED current value stored in the LED drive condition memory 63 in the flow 17 of FIG. 4 is read out and stored as the LED drive condition data P7 in the LED drive condition memory 38 of the exposure apparatus 10, and the flow ends.

ここで、式中の各係数Ａ₀〜Ａ₁₀は、赤緑青の各色ＬＥＤの発光波長毎に異なるが、その数値はここでは省略する。 Next, the relational expression T (H) will be briefly described. The relational expression T (H) is a relational expression common to all the pixels 24 of the LCS 21 and represents the relation between the drive gradation level (H) and the normalized normalized exposure dose T. Further, the relational expression T (H) is a relational expression obtained by the driving characteristics of the LCS 21 and the sensitivity characteristics of the photosensitive material such as the silver salt instant film used. In this embodiment, the subsequent calculation is facilitated. For this reason, the following 10th order polynomial is used to express the result by the least square approximation method.

Here, the coefficients A ₀ to A ₁₀ in the formula is different for each emission wavelength of each color LED of red, green and blue, that number is omitted here.

Next, FIG. 6 shows an example of the correction data H ″ obtained by the flow of FIG. 5. The correction data H ″ is applied to all the drive gradation levels H of each pixel (N = 0 to 479). The corresponding correction driving gradation is stored in the correction data memory 33 of the exposure control circuit 30 described above. still,
Here, the pixel of N = 6 is shown as a pixel corresponding to the minimum light amount Fmin, and the correction data H ″ of the pixel of N = 6 is equal to the drive gradation H. Also, the excluded pixel region (N = 0 to 4) The correction data H ″ is the same as the correction data H ″ at the left end (N = 5) of the adjacent target pixel area, and similarly, the correction data H ″ of the excluded pixel area (N = 475 to 479) is It is the same as the correction data H ″ at the right end (N = 474) of the adjacent target pixel region. Note that the correction data H ″ shown in FIG. 6 is correction data related to the output light from the red LED, and actually is green. Correction data is also obtained for the output light from the LED and the blue LED according to the same procedure and stored in the correction data memory 33 of the exposure control circuit 30.

  Next, the correction data H ″ (that is, the correction data P3 shown in FIG. 1) stored in the correction data memory 33 of the exposure control circuit 30 based on FIG. 1 and the LED driving condition memory 38 stored in the LED drive condition memory 38. An operation of the exposure apparatus 10 in which the shading correction is performed based on the LED current value (that is, the LED driving condition data P7 shown in Fig. 1) will be described with reference to Fig. 1, the image data P1 (bits) via the input I / F 31. When the map data) is input to the shading circuit 32, the shading circuit 32 checks which pixel in the LCS 21 the individual data of the sequentially input image data P1 is exposed (that is, N is obtained). In addition, the correction data H ″ stored in the correction data memory 33 is read using the value of the image data P1 as the drive gradation H, and the read data The positive data H ″ is output as the corrected image data P2 to the LCS control circuit 35. That is, the value of the image data P1 is converted into the correction data H ″ stored in the correction data memory 33 by the shading correction circuit 32, and the corrected image is displayed. The data P2 is input to the LCS control circuit 35.

  Next, the LCS control circuit 35 receives the corrected image data P2 and the exposure timing data P4, corrects the exposure density nonlinearity based on the LUT data P9 from the LUT 36, and then outputs the LCS control signal P5. The LCS drive circuit 37 receives the LCS control signal P5, and outputs an LCS drive signal P6 for driving the LCS 21 with gradation. The LCS 21 built in the exposure head 20 inputs the LCS drive signal P6 via the output I / F 40, and performs a uniform exposure operation by shading correction by driving all the pixels 24 in the pixel row 23 by gradation.

  On the other hand, the LED drive condition memory 38 of the exposure control circuit 30 outputs the stored LED drive condition data P 7 and inputs it to the LED lighting control circuit 39. The LED lighting control circuit 39 receives the LED driving condition data P7 and the exposure timing data P4, is converted into an analog amount by an internal D / A conversion circuit (not shown), and the LED driving current set for each color is converted into an LED. Output as drive signal P8. The LED 28 incorporated in the exposure head 20 receives the LED drive signal P8, is controlled to be lit by the LED drive current set for each color, and operates as an exposure light source of the LCS 21.

  A light amount graph 26 in FIG. 2 shows an example of the light amount characteristic of the exposure head 20 subjected to the shading correction based on the correction data H ″ obtained by the flow of FIG. 5 described above. Since (N = 5 to 474) is subjected to shading correction based on the pixel (N = 6) having the minimum light amount Fmin, the light amount variation is appropriately adjusted. , N = 475-479) is the same as the correction data H ″ of the pixels (N = 5, N = 474) at both ends of the adjacent target pixel region, and is corrected with reference to the light amount of the pixels at both ends. In this case, a variation substantially equal to the variation in the amount of light before correction occurs. However, as described above, the exclusion pixel area is corrected based on the light amount of both end pixels of the adjacent target pixel area, and as a result, the boundary between the exclusion pixel area and the target pixel area is corrected with continuity. There are few steps and changes in the amount of light, the density unevenness of the photosensitive material is improved, and a good image can be obtained in all pixel regions.

In FIG. 2, dotted lines 26a and 26b of the excluded pixel region of the light amount graph 26 are light amount graphs obtained by partially copying the characteristics of the invalid region of the light amount graph 5 of FIG. 7 which has been subjected to shading correction by a conventional exposure apparatus. is there. The effect of the present invention is apparent by comparing the light quantity graph 26 corrected for shading by the exposure apparatus of the present invention with the light quantity graphs 26a and 26b corrected for shading by the conventional exposure apparatus. In other words, in the conventional shading correction results (light quantity graphs 26a and 26b), a difference in the light quantity and a large light quantity fluctuation are observed near the boundary between the effective area where the correction process is performed and the invalid area where the correction process is not performed. However, in the shading correction result (light quantity graph 26) of the present invention, no light quantity step or large light quantity fluctuation can be seen near the boundary between the target pixel area and the excluded pixel area. Further, in the present invention, the vicinity of both ends of a pixel column that is likely to cause a decrease in light amount or a change in response characteristics of LCS is defined as an excluded pixel region, and a region other than the excluded pixel region is defined as a target pixel region, and the minimum light amount within the target pixel region Since the pixel of Fmin is detected and used as a reference for correction, the problem that the amount of light from the LCS decreases after shading correction and the amount of light necessary for exposure cannot be obtained is solved.

  In the present embodiment, the excluded pixel area is set to five pixels at the left and right ends of the pixel row 23. However, the number of pixels is not limited to this, and the excluded pixel area is arbitrarily set according to the light amount distribution characteristics. good. Further, in the present embodiment, the correction data for correcting the light amount of the excluded pixel region is the correction data for the pixels at both ends of the adjacent target pixel region, but this is not limited, and the correction data for the target pixel region is not limited. Any pixel correction data may be used. Further, the circuit block diagram of the exposure apparatus 10 of the present invention shown in FIG. 1 and the block diagram of the measuring system for measuring the light quantity shown in FIG. 3 are not limited to this configuration but satisfy the functions. Any configuration may be used. Further, the flowchart of the light amount measurement for performing the shading correction shown in FIG. 4 and the flowchart for acquiring the correction data for performing the shading correction shown in FIG. 5 are not limited to this operation flow. Any operation flow may be used as long as each purpose can be satisfied.

It is a circuit block diagram of the exposure apparatus of this invention. It is explanatory drawing which shows the pixel arrangement | sequence of LCS of the exposure apparatus of this invention, the light quantity characteristic output from this LCS, and the light quantity characteristic of the result of having performed the shading correction. It is a block diagram which shows the structure of the measurement system which performs the light quantity measurement for performing shading correction | amendment to the exposure apparatus of this invention. It is a flowchart of the light quantity measurement for performing the shading correction of the exposure apparatus of this invention. It is a flowchart which acquires the correction data for performing the shading correction of the exposure apparatus of this invention. It is a correction data table showing an example of correction data for performing shading correction of the exposure apparatus of the present invention. It is explanatory drawing which shows the light emission pixel arrangement | sequence of the optical printer head using the conventional fluorescent light emission tube, the light quantity characteristic output from this light emission pixel, and the light quantity characteristic of the result of having performed the conventional shading correction. It is explanatory drawing which shows the response characteristic of the pixel column center vicinity of LCS, and pixel pixel both ends vicinity.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical printer head 2, 3 Light emission pixel row 4, 5, 25, 26 Light quantity graph 10 Exposure apparatus 20 Exposure head 21 LCS
22a, 22b Glass substrate 23 Pixel row 24 Pixel 28 LED
30 Exposure control circuit 31 Input I / F
32 Shading correction circuit 33, 66 Correction data memory 34 Exposure correction circuit 35 LCS control circuit 37, 62 LCS drive circuit 38, 63 LED drive condition memory 39 LED lighting control circuit 40 Output I / F
50 Measuring device 51 Exposure device I / F
52 Current Supply Circuit 53 PC-I / F
60 Driving condition signal creating means 61 CPU
64 LCS drive condition memory 65 light amount memory 70 light amount measuring means 71 CCD line sensor 72 CCD control circuit 73 received light amount detection circuit 74 integration circuit 80 PC
P1 Image data P2 Correction image data P3 Correction data P6 LCS drive signal P7 LED drive condition data P8 LED drive signal

Claims (2)

The luminescence pixel row including a plurality of light emitting pixels, and supplies the image data performs gradation exposure, the light-emitting image individually by Ri Luminous each pixel measured and obtained compensation data to the light emitting output of the unit In an exposure apparatus that performs light quantity correction to make the light quantity uniform.
A predetermined number of light emitting pixel regions from both ends of the light emitting pixel column are excluded pixel regions, and other pixel regions are target pixel regions, and the target light emitting pixels constituting the target pixel region are based on respective light emission outputs. It performs light amount correction using the correction data created,
Exposure apparatus and supplying the corrected data of the target emission pixels at both ends of the target pixel area, commonly to exclude light emitting pixels all negative pixel regions adjacent respectively. A light-emitting pixel row formed of a plurality of light-emitting pixels for performing gradation exposure by the image data supplied, the light emitting image by Ri onset light into compensation data obtained by measuring the light output to each element in the light amount correction method for an exposure apparatus which performs light amount correction for uniformizing the light quantity for each pixel,
A predetermined number of light emitting pixel regions from both ends of the light emitting pixel column are excluded pixel regions, and other pixel regions are target pixel regions, and the target light emitting pixels constituting the target pixel region are based on respective light emission outputs. create a correction data, performs light amount correction using the correction data,
Light amount correction method of an exposure apparatus and supplying the corrected data of the target emission pixels at both ends of the target pixel area, commonly to exclude light emitting pixels all negative pixel regions adjacent respectively.

Images