JPH01217335A - Measuring method for exposure quantity of color copying machine and measuring method for copying density - Google Patents

Abstract

PURPOSE:To correctly know a reading position by taking the difference between metered values or two points of their corresponding values, detecting the ends of patterns and measuring exposure quantity in a prescribed position between the ends of patterns. CONSTITUTION:A test chart 11 possessing plural patterns of different colors is placed on an original placing plane 10 and is scanned optically. A metering means 33 measures its reflected light. In that case, a metered value is obtained by taking the difference between two points corresponding to values, and the ends of patterns are detected. The exposure quantity of a color copying machine is measured in a prescribed position between said ends. A logarithmically converted value, and values converted according to functions and conversion tables to correspond with lightness, etc., are used for values corresponding to the metered values of the test chart 11. Thus, a reading position can be found correctly even if an original is set incorrectly.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a color copying machine suitable for copying color originals having halftones, for example, a silver salt copying machine that uses reversal color paper, a diffusion transfer type photosensitive material, etc. Exposure measurement method and copy density measurement method used in photo color copying machines (optical printers), electrophotographic color copying machines, thermal transfer color copying machines, inkjet color copying machines, racer color copying machines, video color copying machines, etc. Regarding.

[Conventional technology]

In a color copying machine, copying conditions are set or adjusted when the device is installed and periodically thereafter, so that color copies with colors and densities faithful to the color original are created.

- In boat fishing, the factors that affect the density and color reproducibility of color copies include variations in the copying optical system and changes over time, variations in the properties of the recording material and changes over time, variations in the properties of the developing material and changes over time, Because of variations in developing conditions, etc., it is necessary to set copying conditions for each color copying machine even if the model is the same.

For example, in a silver-halide photographic color copying machine, factors based on the optical system include variations in the optical system such as the light source, lenses, color filters, mirrors, exposure measurement sensors, and the scanning speed of the slit light, as well as changes over time. It will be done. Furthermore, factors based on the recording material include changes in the type and characteristics of the photosensitive material over time, variations between lots, and the like. Factors based on the developing material include variations in the properties of the developer and changes over time. Furthermore, factors based on development conditions include development temperature and development time.

Various methods have been known to date for setting such copying conditions.

For example, Japanese Patent Laid-Open No. 61-14663 discloses that a B/W copy in which stripes with different densities are recorded is produced by controlling the luminance of the light source or the developing bias voltage of the developing device during one copying operation. A method is disclosed in which the density is set by creating a copy and visually judging the copy.

Further, Japanese Patent Application Laid-Open No. 60-243649 discloses a method of finding the optimum exposure amount by visually judging a copy obtained by exposing a test chart while changing the exposure amount.

This method is excellent in principle in that it can create a B/W copy whose density changes in stripes by changing the exposure amount and development conditions.

However, since the exposure amount is corrected by visual judgment of the copy, considerable skill is required to apply it to a color copying machine and correct each of the three colors (blue, green, red) in a well-balanced manner. .

Therefore, in order to deal with such problems, the present inventors
First, we used a test canid in which multiple patterns with different densities were recorded for each of the three primary colors, set it on the document placement surface, performed optical scanning, and measured the three primary color components of the reflected light using each measuring means. Measure each color to find the exposure amount for each color, operate the image recording system to create a color copy of the test chart, set this color copy on the document placement surface, perform optical scanning, and record the three primary colors of the reflected light. measuring the components with each measuring means, logarithmically converting the amount of reflected light of each color obtained to obtain a copy density value, and creating characteristic data for each primary color light indicating the relationship between the copy density value and the exposure amount;
A color copying condition setting method for adjusting the insertion amount of each filter into an optical path so as to match pre-known reference characteristic data of each color. ” (Patent Application No. 62-37249).

[Problem to be solved by the invention]

However, even with the above method, when the test chart and this color copy are set on the document placement surface when creating characteristic data, there is a problem that these items are not always set correctly, and that the test chart is not always set correctly. There are problems in that stability over time and the like are not necessarily high, and that it is difficult to stably and accurately measure test charts having a large number of patterns.

SUMMARY OF THE INVENTION An object of the present invention is to provide an exposure measurement method and a copy density measurement method for a color copying machine, which can accurately determine the reading position.

[Means to solve the problem]

In order to achieve the above object, the exposure measuring method for a color copying machine according to the present invention is such that a test chart having a plurality of patterns with different densities is set on a document placement surface and scanned with light, and the reflected light is measured by a photometer. The exposure amount is measured by measuring at a predetermined position between the edges of each pattern by taking the difference between two points of the photometric value or its corresponding value to detect The exposure amount is measured.

The method for measuring copy density of a color copying machine according to the present invention involves setting a test chart having a plurality of patterns of different densities on a document placement surface, scanning and exposing it to create a copy image, and then optically scanning this copy image. The reflected light is measured by a photometric means, and the copy density of the obtained copy image is measured, and at this time, the edge of the pattern is detected by taking the difference between two points of the photometric value or its corresponding value, The copy density is measured at a predetermined position between the edges of each pattern.

Then, the above-mentioned exposure measurement method and copy density measurement method can be applied to form a color copying condition setting method. is set on the document placement surface and optically scanned, and the three primary color components of the reflected light are measured using each photometric means to determine the exposure amount for each color, and the image recording system is activated to make a color copy of the test chart. Next, set this color copy on the original document surface, perform optical scanning, measure the three primary color components of the reflected light with each photometer, logarithmically convert the obtained reflected light amount of each color, and copy. The density value is determined, characteristic data indicating the relationship between the copy density value and the exposure amount is created for each primary color light, and the amount of insertion of the color filter into the optical path is made so as to match the reference characteristic data of each color known in advance. At that time, the edge of the pattern is detected by taking the difference between the photometric values of the test chart and the color copy or their corresponding values, and the predetermined position between the edges of each pattern is detected. The characteristic data is created by determining the exposure amount for a test chart and the copy density value for a color copy.

[For production]

According to the present invention, a test chart having a plurality of patterns with different densities is set on a document placement surface, optically scanned, and the reflected light is measured by a photometric means. In this case, the edges of the pattern are detected by taking the difference between the photometric values or their corresponding values at two points, and the exposure amount of the color copying machine is measured at a predetermined position between the edges of each pattern.

According to the present invention, a test chart having a plurality of patterns with different densities is set on a document placement surface and scanned and exposed to create a copy image. This copy image is optically scanned, and the reflected light is measured by a photometer. In this case, the edges of the pattern are detected by taking the difference between two photometric values or their corresponding values, and the copy density of the color copying machine of the copy image is measured at a predetermined position between the edges of each pattern.

To set copying conditions by applying the present invention, first, a test chart is set on the document placement surface, and the chart is optically scanned to measure the reflected light and a color copy is created.

Next, the obtained color copy is set on the document placement surface, optical scanning is performed, reflected light from the color copy is measured, and the obtained measured value is logarithmically converted to obtain a copy density value.

In this case, the edge of the pattern is detected by taking the difference between the photometric values of the test chart and the color copy or their corresponding values, and the exposure amount is determined at a predetermined position between the edges of each pattern. For color copying, the copy density value is also determined.

Characteristic data is created for each color from this copy density value and the exposure amount obtained from the first optical scan.

The deviation between the characteristic data and the reference characteristic data is determined from the actually measured characteristic data and the reference characteristic data known in advance, and the insertion amount of the color filter into the optical path is adjusted by the amount corresponding to this deviation.

〔Example〕

Examples will be described with reference to the drawings.

FIG. 1 shows a silver halide photographic color copying machine (hereinafter referred to as "color copying machine") as an embodiment of an image recording apparatus to which the color copying condition setting method using the exposure amount measurement method and copy density measurement method of the present invention is applied. A schematic configuration diagram of a copying machine (sometimes abbreviated as a copying machine) is shown.

As shown in FIG. 1, when setting the copying conditions, the test chart 11 is placed with the original surface facing down on the transparent original placing surface 10, and the original holding plate whose lower surface is white. It is held down by 12. During copying, a color original is placed on the original placement surface 10. Further, a white reference plate 13 is attached to the lower surface of the left end of the document placement surface 10.

The light source unit 14 includes a light source 15, a reflector 16, and a mirror 17, and reciprocates in parallel with the document placement surface 10 to slit-illuminate the test chart 11 or the color document. The mirror unit 18 holds two mirrors 19 and 20 extending in a direction perpendicular to the plane of the paper, and returns the light from the light source unit 14 in parallel.

Further, this mirror unit 18 moves in the arrow direction during magnification conversion.

The lens unit 22 moves back and forth along the optical axis in synchronization with the light source unit 14 in order to correct the focal shift caused by the movement of the light source unit 14. This lens unit 22
A yellow filter Y1, a magenta filter M1, and a cyan filter C are arranged near the principal point of the lens between the front group 23 and the rear group 24. These color filters Y, M
, C are movable in the direction perpendicular to the optical axis,
The light quality of the slit light is adjusted by the amount of insertion in the optical path, and the color balance is corrected. Such a Lylter device is described, for example, in Japanese Patent Publication No. 44-2542. Further, behind the rear group 24, two aperture plates 25 and 26 that move in opposite directions are arranged.

In the illustrated example, the two aperture plates 25 and 26 are movable, but they may be fixed.

Further, an ND filter may be added in addition to the color filters Y and M%C.

Each color filter Y, M%C and aperture plate 25 if necessary
．． 26 includes a drive unit 131.1 as shown in FIG.
32.133.134 are provided.

These driving units 131 to 134 may normally be driven using pulse motors, solenoids, or the like.

The light passing through the lens unit 22 passes through the mirror 28.2.
After being turned back at 9, it reaches an optical path switching mirror 31 whose rotation center is an axis 30. When measuring the reflected light, the condensing mirror 32 was inserted into the optical path as shown by the dotted line, and the optical path changing mirror 31 was also withdrawn from the optical path as shown by the dotted line to collect the reflected light from the test chart 11. In this state, it is put into the photometry means 33.

The condensing mirror 32 includes a plurality of mirrors 32a, and as shown in FIG. 2, each mirror 32a is arranged at an angle corresponding to the distance from the optical axis, so that almost all of the slit light is Or focus a part of the light. The photometric means 33 includes a red sensor 33a and a green sensor 33.
b1 blue sensor 33c, and measures the three-color light components of the reflected light.

A control means 50 is connected to the photometry means 33 .

The control means 50 controls the color filters Y, M, and C through their driving sections 131 to 133 according to copying conditions set as described below.

The control means 50 is composed of known control means, and includes a CPU
The above-mentioned copying conditions are stored in a known storage means together with the I10 board and the I10 board.

A photosensitive material 36 is stored in the magazine 35 in the form of a roll. This photosensitive material 36 is drawn out by a pair of drawing rollers 37 and 38, and after being drawn out a certain length, is cut by a cutter 39. This cut photosensitive material 36a has its tip end at the roller pair 40.4.
1 and stop at the bitten position. This roller pair 40.
A pair of rollers 42 and 43 are arranged opposite to 41, and a slit exposure position is formed between these four rollers 40 to 43, into which light from the optical path switching mirror 31 enters.

During copying, the rollers 40 to 43 rotate in synchronization with the light source unit 14, and a processing section (not shown) is installed for processing the exposed photosensitive material 36a. In this processing section, development, bleaching/fixing, and washing are performed.

A take-out tray (not shown) for sending out the dried photosensitive material 36a is provided downstream of the processing section.

Next, setting of copy conditions will be explained with reference to FIG.

When setting conditions, a mote designation key (not shown) is operated to set the copy condition setting mote.

Next, after setting the test chart 11 on the document placement surface 10, the copy key (not shown) is operated. In this copying condition setting mode, color filters Y, M, and C and aperture plates 25 and 26 are set at standard positions. Further, the condensing mirror 32 is inserted into the optical path as shown by the dotted line, and the optical path switching mirror 31 is retracted to the position shown by the dotted line.
After this, the light source unit 14 and the lens unit 22 move synchronously, illuminate the reference plate 13 and the test chart 11 with slit light, and perform the 51st scan.

The reflected light from the reference plate 13 and the test chart 11 is
The light passes through the mirrors 17, 19 to 20, the lens unit 22, and the mirrors 28, 29 in order, and then enters the condensing mirror 32.

As shown in FIG.
lead to. This photometry means 33 includes a red color sensor 33a.
, a green sensor 33b, and a blue sensor 33c, each of the three color components of the reflected light is measured.

The test chart 11 described above has a black band 11a recorded at the tip, as shown in FIG. A pattern of stripes Ilb is formed at equal intervals. These stripes fib extend in a direction perpendicular to the moving direction of the light source unit 14. In this embodiment, four stripes 11b are recorded for each of cyan, magenta, and yellow, making it possible to perform density measurements at four levels for each color.

In the above description, four patterns of stripes flb are formed, but the present invention is not limited to this, and the number of patterns of stripes 11b may be at least two or more corresponding to the image density. However, the more patterns there are in the stripes 11b, the more accurately the copying conditions can be set.

The exposure amount is determined from the photometric values of such a test chart. In this case, the difference between the two points of the photometric value or its corresponding value is taken to detect the edge of each pattern, and the predetermined distance between the edges of each pattern (points P, Q, R, S, T in Figure 5) is detected. position,
For example, the average value of a predetermined range centered on the 1/2 position between PQ in FIG. 5 is determined. Note that, as the value corresponding to the photometric value of the test chart, for example, a logarithmically converted value of the photometric value, a converted value obtained from a functional formula or a conversion table corresponding to brightness, etc. is used.

The exposure amount determined in this way is usually stored as a value as it is or as a logarithmically converted value.

When the light source unit 14 moves to the left end and the first scan is completed, copying of the test chart 11 is started. In this case, the optical path switching mirror 31 is inserted into the optical path as shown by the solid line, and the condensing mirror 32 is also withdrawn from the optical path. At the same time, feeding of the photosensitive material 36 is started, and the photosensitive material 36 is drawn out by a pair of rollers 37 and 38, and cut by a cutter 39 when it has been drawn out a certain length. During this cutting, since the tip of the photosensitive material 36a is caught by the rollers 42.43, the photosensitive material 36a is further fed by the rollers 42.43. When the tip of the photosensitive material 36a is bitten by the roller pair 40, 41, the roller 4
0-43 rotation stops.

After setting the photosensitive material 36a, the return stroke of the light source unit 14 is started, thereby performing the second scan. In this second scanning, the rollers 40 to 43 rotate in synchronization with the return of the light source unit 14, and the photosensitive material 36a
is continuously moved and subjected to slit exposure. By this slit exposure, the image of the test chart 11 is recorded as a latent image on the photosensitive material 36a.

Thereafter, in a processing section (not shown), it is subjected to various processes such as development, bleaching/fixing, and washing with water, and is taken out after drying to obtain a color copy of the test chart.

Next, the test chart 11 is removed from the document placement surface 10, and a color copy is set in its place. When the copy key (not shown) is operated, the optical path switching mirror 31 is retracted from the optical path and the condensing mirror 32 is inserted into the optical path, as in the first scanning. Thereafter, the forward stroke of the light source unit 14 is started, and the third scan is performed. In this case, similarly to the first scan, the light reflected from the color copy is measured by the photometry means 33.

The light quantity signals outputted from each of the sensors 33a to 33c are logarithmically converted, and from this value and the logarithmically converted value of the photometric value of the reference plate 13, the copy density is determined.

When determining the copy density, the edge of each pattern is detected by taking the difference between two photometric values or their corresponding values in the same manner as the exposure amount described above, and the average value of a predetermined range is determined.

Then, this copy density is stored.

As the value corresponding to the photometric value, similarly to the corresponding value of the photometric value in the test chart, a logarithmically converted value of the photometric value or a converted value based on a functional formula or a conversion table corresponding to brightness, etc. is used.

In the above-mentioned exposure amount and copy density, the two points when detecting the edge of each pattern by taking the difference between the two points may be adjacent points or may be points several points apart.

Although it depends on the number of patterns on the test chart, it is preferable to set the number of points to less than 20 when several points are passed.

In addition, as shown in Fig. 4, for example, the etch existing range or measurement area of each pattern from the black tip mark is memorized, and the exposure amount or the average copy density of the area determined by photometry is calculated. You can.

In this case, the tip mark may be not only black but also white, other colors, densities, and notches.

Alternatively, the edge of each pattern may be detected based on the difference between two points between the existing range of the edge of each pattern from the tip mark and the photometric value for that range or its corresponding value.
Note that the leading edge mark may be detected by taking the difference between two points in the above-mentioned exposure amount and copy density to detect the edge of the leading edge mark or the center position of the leading edge mark. Another simple detection method may be to detect a specific color or density near the tip.

Further, the tip mark may be provided in contact with the pattern of the test chart, or may also serve as the pattern.

The distance from the tip mark must be determined based on data such as the end position, the area that always includes the end position, the photometry position, the area that always includes the photometry position, the start of the photometry amount or the end of the photometry, and the photometry interval. good.

Furthermore, after detecting the ends, the position of each end may be corrected based on the plurality of ends found.

Furthermore, edge detection does not necessarily need to be performed for all patterns, and the position of the edge of each pattern may be determined or corrected based on the edge of a specific pattern or the edge with the highest detection accuracy.

When the third scan is completed, the light source unit 14 returns to the initial position.

The signals of the exposure amount or its logarithmically converted value obtained in the first and third slit scans and the signal of the copy density value are read out from the storage means, and the relationship between the exposure amount or its logarithmically converted value and the copy density is determined. Create characteristic data for each color.

In this case, an interpolation method may be used. Further, the characteristic data may be a relational expression or a table value.

The above characteristic data is compared with reference characteristic data of each color known in advance.

The reference characteristic data may be determined based on the design, or may be measured by the procedure described above when installing the color copying machine, and the obtained data may be written into the storage means.

Note that the reference characteristic data may be a series of data groups of a signal of an exposure amount or its logarithmically converted value and a signal of a copy density value, or a pair of data for each color.

The light source unit 4 returns to the initial position and moves to the reference plate 1.
3 is slit-illuminated, the light reflected from this reference plate 13 is measured by the photometry means 33. Using the blue exposure amount, green exposure amount, and red exposure amount obtained in this measurement as reference values, measure while moving the yellow filter Y, magenta filter M, and cyan filter C, respectively, and check for deviations from the standard characteristic data (for example, the same The camera is placed at a position that is increased or decreased by an amount corresponding to the difference in light amount (difference in light intensity, etc.) that affects the copy density. This completes the setting of copy conditions.

The reference plate used for setting the above-mentioned copying conditions may be gray or the like instead of white. In addition, the relationship between the exposure amount of each color and the amount of movement of the corresponding color filter is memorized, the position of the color filter corresponding to the reference data is determined, and then the deviation of the exposure amount calculated as described above is calculated. The copying conditions can be set by modifying the amount of movement of the color filter corresponding to the amount of movement of the color filter.

After setting the copy conditions, a mode designation key (not shown) is set to copy mode. In this copying mode, the condensing mirror 32 is retracted from the optical path, and the optical path switching mirror 31 is retracted from the optical path.
or inserted into the optical path. When copying a color original, the color original is set on the original placing surface 10 and pressed from above with the original holding plate 12. Next, when a copy key (not shown) is turned on, a color copy is created in the same manner as the above-described test chart copying procedure. In addition,
In this case, the photosensitive material 36a is exposed during the forward stroke of the light source unit 14.

In this example, no color correction is performed on individual color originals, or the image quality is high.In order to obtain a good color copy,
Is it possible to perform color and density corrections appropriate for color originals?

In this case, in the forward stroke of the light source unit 14, the three-color density of each point on the color original is measured, and according to the three-color density, the position determined in the copying condition setting mode is set as a reference.
Adjust the amount of color filters Y, M, and C inserted into the optical path.
Then, during the return stroke of the light source units 1 to 14, a color original is copied.

In the embodiments described above, test charts 1 to 1 may be created and used in a pseudo manner by using test charts or by inserting color filters Y, M, and C into the optical path.

In the present invention, the first photometry and the second color copy creation may be performed simultaneously.

For example, instead of the optical path switching mirror 31, a half mirror that partially reflects and partially transmits light may be used to create a color copy at the same time as photometry. Further, in a color copying machine using digital processing such as an inkjet color copying machine or a laser color copying machine, color copies can be created by performing image processing at the same time as photometry of a test chart.

In the above, a silver halide photographic color copying machine is mentioned as an image recording device, but it is not limited to this, and includes an electrophotographic color copying machine, a thermal transfer color copying machine,
Inkjet color copying machine, laser color copying machine,
It may also be a video color copier.

(Effects of the Invention) According to the present invention, the edges of the patterns are detected by taking the difference between the photometric values of the test chart and the color copy or their corresponding values, and the edges of the patterns are detected at predetermined positions between the edges of each pattern. Since the test chart measures the exposure amount or its logarithmically converted value, and the color copy of the test chart measures the copy density, the reading position can be accurately determined even if the original is set incorrectly.

Furthermore, the number of patterns can be increased, and by increasing the number of patterns, accurate measurement is also possible.

In fact, the color copying condition setting method using the above measurement method is highly accurate.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing one embodiment of a silver salt photographic color copying machine to which the present invention is applied. FIG. 2 is a sectional view showing the function of the condensing mirror. FIG. 3 is a block diagram for explaining a method of setting copy conditions. FIG. 4 is an explanatory diagram of a test chart. 5A to 50 are graphs showing the density of the test chart. Explanation of symbols 10... Original placement surface, 1, 1... Test chart, 12... Original holding plate, 13... Reference plate, 14
...Light source unit, 22...Lens unit, Y.
...Yellow filter, M...Magenta filter, C...Cyan filter, 31...Optical path switching mirror, 32...Condensing mirror, 33...Photometering means, 36.36a...Photosensitive material , 50...Control means patent applicant Fuji Photo Film Co., Ltd. Agent Patent attorney Nozomu Watanabe Minoru Patent attorney Yo Ishii -1 Indication of the case Patent Application No. 43137 of 1988 2 Name of the invention Related Patent Applicant Address 210 Nakanuma, Minamiashigara City, Kanagawa Prefecture Name (520) Fuji Photo Film Co., Ltd. 4 Agent
Person: 101 Telephone: 864-4498 Address: 3-2-2-6 Iwaki-cho, Chiyoda-ku, Tokyo Contents of the amendment (1) On page 27 of the specification, line 5, after “I can do it.” It is also possible to generate a test signal instead of a chart and create a color copy without using a test chart." is inserted.

Claims (2)

[Claims] (1) In an exposure measurement method for a color copying machine, in which a test chart having multiple patterns with different densities is set on the document placement surface and scanned with light, and the reflected light is measured by a photometer to measure the exposure amount. , a color copying machine characterized in that the edges of a pattern are detected by taking the difference between two points of photometric values or their corresponding values, and the exposure amount is measured at a predetermined position between the edges of each pattern. Exposure measurement method. (2) A test chart with multiple patterns of different densities is set on the document placement surface and scanned and exposed to create a copy image, the copy image is scanned with light, and the reflected light is measured with a photometric means. In the copy density measurement method for color copiers that measures the copy density of a copied image, the edge of a pattern is detected by taking the difference between two photometric values or their corresponding values, and the difference between the edges of each pattern is detected. A copy density measuring method for a color copying machine, characterized in that the copy density is measured at a predetermined position.