JP3262025B2 - Measuring method of light intensity of luminescent dots - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for measuring the amount of light of a light emitting dot in a line light source having a plurality of light emitting dots arranged in one or a plurality of rows. For example, detecting the arrangement of a plurality of light emitting dots in the arrangement of the line light source for the print head, measuring the light amount of each light emitting dot at an accurate position, and creating correction data for equalizing the light emitting amount of the plural light emitting dots This is suitable for measuring the amount of light to be performed.

[0002]

2. Description of the Related Art FIG. 6 is an external view of a vacuum fluorescent tube for an optical printer. In the figure, 1 is a vacuum fluorescent tube, 1a is a substrate, 1b is a light transmitting part, 2 is a light emitting dot, and 51 is a photosensitive film.
The vacuum fluorescent tube 1 is an example of a linear light source in which a plurality of light emitting dots are arranged on a straight line. Substrate 1 of vacuum fluorescent tube 1
On “a”, a plurality of light emitting dots 2 are provided on two lines in a straight line, and are arranged in a staggered manner in which the lines are changed every other dot at the same pitch. The upper surface of the substrate 1a on which the light emitting dots 2 are provided is covered with a light transmitting portion 1b, and the substrate 1a and the light transmitting portion 1b form an envelope and the inside is evacuated. The outer shape of the luminescent dots 2 is about 100 μ, and the row interval is about 1.1 mm. In addition,
In some cases, the plurality of light emitting dots 2 are provided on three or more lines of a plurality of straight lines. In this case as well, each light emitting dot 2 is periodically distributed and arranged in each line by changing the line by one dot. The light emitting dots 2 emit light by the impact of electrons emitted from a linear cathode (not shown).

A photosensitive film 51 is disposed on the upper surface of the light transmitting portion 1b via a condensing lens portion such as a selfoc lens array not shown in FIG. The photosensitive film 51 and the vacuum fluorescent tube 1 and the condenser lens side are relatively moved in the main scanning direction with the direction perpendicular to the main scanning direction. As the photosensitive film 51, an instant photographic film or the like is used, and the light emitting dots 1 are sequentially exposed linearly in the sub-scanning direction by emitting light. In the sub-scanning direction, first, every other dot is linearly exposed by each light emitting dot 1 in the first row, but as the movement in the main scanning direction, the area not exposed by each light emitting dot 1 in the second row is exposed. Is done. When the entire movement in the main scanning direction is completed, an image is formed on the photosensitive film 51. In this example, the case where an image is formed directly on a recording medium has been described. However, there is also a case where a charged photosensitive drum is exposed to form a latent image, which is developed and transferred to paper.

In such a light source for an optical printer, the brightness of each light emitting dot is not uniform, and each light emitting dot 1
Have a variation of about ± 20%. Therefore, in order to improve print quality, it is necessary to make the light amount of each light emitting dot 1 as uniform as possible. For this reason, conventionally, the brightness of each light emitting dot is measured using a photomultiplier tube to generate light amount correction data, and the light amount is corrected at the time of image formation.

FIG. 7 is a schematic block diagram of a conventional printer light source and a diagram for explaining a conventional light amount correction method. In the figure, 1 is the vacuum fluorescent tube shown in FIG. 6, 61 is a multiplier, 62 is a ROM, 63 is a pulse width modulator, 64 is a grayscale clock generator, and 65 is an anode driver. FIG.
Now, the function of light quantity correction will be described conceptually. The vacuum fluorescent tube 1 has a plurality of anode electrodes on which phosphors are adhered, and a planar grid electrode provided around the anode electrodes to increase the selection action and the brightness.

As will be described later with reference to FIGS. 8 and 9, in order to correct the variation in the luminance of each light emitting dot of the vacuum fluorescent tube 1, the average luminance of each light emitting dot is previously determined using a photomultiplier tube. Relative value), an exposure table for correction is written into the ROM 62, and the light emission time is controlled by referring to a correction value for input data at the time of exposure.
The light amount is made uniform.

FIG. 7A is a schematic block diagram of a light source for a printer. Input image data for controlling the i-th anode of the vacuum fluorescent tube 1 is represented by G (i) (0 ≦ G (i) ≦
1). The input image data G (i) is multiplied by the multiplication unit 6
1, L _std / L read from the ROM 31
(I) and exposure data L ′ (i) (0 ≦ L ′).
(I) ≦ 1) is output. That is, the following equation holds. L ′ (i) = (L _std / L (i)) × G (i) (1)

FIG. 7B is a diagram for explaining light quantity correction. L (i) is the light amount when the light emitting dot 2 of the dot number (i) is caused to emit light with the maximum pulse width. L
_std is the target light amount when the light emission amount of all the light emitting dots 2 of the vacuum fluorescent tube 1 is made uniform, and for example, the light emission amount of the light emitting dot which has the smallest luminance but satisfies the standard value among all the light emitting dots 2 Adjust to In order to correct the light amount so as to achieve the target light amount, the pulse width of the light emitting dot 2 of the dot number (i) is set to (L _std / L (i)). Further, in order to make the light emission amount proportional to the input image data G (i), G
By multiplying (i), the above equation (1) is obtained.

The exposure data L ′ (i) is input to a pulse width modulator 63. Each time the pulse width modulation unit 63 is reset by a clear signal of a predetermined cycle, the clock pulse from the gradation clock generation unit 64 is exposed to the exposure data L ′.
The exposure data L ′ (i) is counted by counting the number corresponding to (i).
Generates a pulse signal having a width corresponding to. When the pulse width is controlled by 8 bits, 2 ⁸ −1 = 255 types of pulse widths can be obtained, and 255 gradations can be controlled. L mentioned above
_std / L (i) is such that the gradation representing the input image data G (i) is 255 × (L _std / L (i)) for light amount correction.
Means to decrease.

An anode driver 65 supplies an anode voltage to each anode electrode. The pulse signal output from the pulse width modulation unit 63 is supplied to the anode driver 65 and becomes the pulse width of the drive signal applied to the i-th anode electrode, and the light emission amount of the i-th light-emitting dot 2 is corrected. The gradation is controlled according to the input image data G (i).

Light emitting dot 2 of dot number (i) described above
Is determined by the following light quantity measurement. FIG. 8 is a perspective view of a light quantity measuring device for explaining a conventional light quantity measuring method. In the figure, the same parts as those in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted. 2a is a light emitting dot during light emission, and 13 is a photomultiplier tube. For the measurement,
A photoelectric sensor that converts light into an electric signal is required. Currently, photomultiplier tubes are used. An anode voltage having the same size and the same pulse width is applied to each light emitting dot 2 so that each light emitting dot 2 emits light one by one for the same time and the photomultiplier tube 13 emits light during this light emission. The light emission amount is measured while being positioned on the dot 2a. In this figure,
The vacuum fluorescent tube 1 to be measured is placed on the XY plane, and is moved relatively to the photomultiplier tube 13 to measure the light amount of each light emitting dot 2.

FIG. 9 is a perspective view of a photomultiplier, a side view of a conventional light quantity measuring device, and a sensitivity distribution characteristic diagram of the photomultiplier. In the drawings, the same parts as those in FIGS. 6 and 8 are denoted by the same reference numerals, and description thereof will be omitted. Reference numeral 71 denotes a condenser lens, 72 denotes a diffusion plate, and 13a denotes a light receiving window. As shown in FIG. 9A, the photomultiplier tube 13 has a light receiving window 13a having a diameter d. At present, a photomultiplier tube 13 is used as a photoelectric sensor. The diameter d of the light receiving window 13a is about 10 mmφ.
Which is sufficiently larger than the value of about 100 μm, which is the size of the light emitting dot 2. As shown in FIG. 9B, a diffusion plate 82 is provided on the front surface of the light receiving window 13a, and the light incident from the light receiving window 13a is converted into an electric signal. The spatially propagating light from the light emitting dot 2a passes through a condenser lens 71 such as a selfoc lens array, and the light from the light emitting dot forms an image on the diffusion plate 72. Note that this condenser lens 71
Is provided between the vacuum fluorescent tube 1 and the photosensitive film 51 when the vacuum fluorescent tube 1 is used as an optical pudding head in FIG.

The row interval between the light emitting dots 2 of the vacuum fluorescent tube 1 is
As described above, the diameter is about 1.1 mm, which is considerably smaller than the diameter of the light receiving surface 13a of the photomultiplier tube 13 of about 10 mm. The guideline of the position to be adjusted in the Y direction is visually adjusted so that the center of the photomultiplier tube 13 is located between the two rows of the light emitting dots 2. Then, the light intensity of each light emitting dot 2 is measured while moving the photomultiplier tube 13 in the X direction.

However, the photomultiplier tube 13 has a sensitivity distribution characteristic as shown in FIG. 9C even when the diffusion plate 82 is used. The relative sensitivity is highest when the incident point-like light reaches the center of the diameter d of the light receiving window 13a, and the change in the vicinity of the center is the smoothest. The sensitivity rapidly decreases near the boundary of 13a. Therefore, as described above, if the positioning is performed in units of about 1 mm, an error in the sensitivity difference occurs as a light amount measurement value due to a difference in sensitivity due to a shift in the relative position between each row and the photomultiplier tube 13. As a result, an error naturally occurs in the light amount correction value, and as a result, 1
Light and dark lines appear every other line.

Therefore, for all the light emitting dots 2 shown in FIG. 8, the relative distance in the vertical direction between the emitting dot 2a whose light quantity is to be measured and the light receiving window 13a of the photomultiplier tube 13 is equal, and XY The measurement must be performed such that the emission dot 2a to be measured is located at the center of the light receiving window 13a of the photomultiplier tube 13 on a plane.

If the vacuum fluorescent tube 1 and the photomultiplier tube 13 are manually and strictly aligned at the time of measuring the amount of light, the alignment can be performed with higher precision than in the prior art. However, when assembling a line light source composed of a plurality of light emitting dots 2 as a module of the vacuum fluorescent tube 1, an error of about 0.5 mm occurs for each product due to a tolerance of each component. Positioning on the basis of is meaningless. In addition, there is also a problem that each time the module of the vacuum fluorescent tube 1 is replaced and attached to the holder of the measuring device, the actual matching must be performed.

[0017]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and is intended to solve the problem even when the arrangement of a plurality of light emitting dots in a line light source is not accurately positioned with respect to a measuring device. It is another object of the present invention to provide a method for measuring the light quantity of a light emitting dot, which can accurately detect the position of the light emitting dot, so that the light quantity of the light emitting dot can be measured with high accuracy.

[0018]

According to a first aspect of the present invention, in a line light source having a plurality of light emitting dots arranged in one or more rows, each light amount of the plurality of light emitting dots is measured by a photoelectric sensor. a light amount measuring method of the luminous dots to be measured by using, together with the relatively moves the photoelectric sensor relative to the plurality of luminous dots, at least two predetermined JP <br/> of the plurality of luminous dots The light emitting dots are sequentially moved with the relative movement of the photoelectric sensor.
Next , the lighting control is performed individually, and the photoelectric sensor receives the light of the specific light emitting dot , and determines the position of the specific light emitting dot.
Searching sequentially and individually, detecting the arrangement of the plurality of light emitting dots, based on the detected arrangement data of the plurality of light emitting dots, moving the photoelectric sensor relative to each other, and detecting the plurality of light emitting dots. The lighting control is sequentially performed, and the light quantity of each of the lighted dots is sequentially measured by the photoelectric sensor at a predetermined relative position based on the position of each of the lighted dots.

Therefore, since the positions of at least two specific light emitting dots are searched by the photoelectric sensor that receives the light of the light emitting dots, it is not necessary to newly provide a special structure for position detection in the line light source. . The arrangement of a plurality of light emitting dots is obliquely assembled with respect to the envelope of the line light source, or this envelope is installed obliquely with respect to the measuring device. Even if the positioning is not accurate, the positions of the plurality of light-emitting dots can be accurately determined from the positions of the searched specific light-emitting dots. Since the position of a specific light-emitting dot is determined based on the photoelectric sensor that receives the light of the light-emitting dot, the position is detected by the same means as that for measuring the amount of light, and the optical characteristics and physical structure of the light-emitting dot and the photoelectric sensor are used. This is not affected even if there is a variation in the correspondence relationship with.

According to a second aspect of the present invention, in a line light source having a plurality of light emitting dots arranged in two rows in a staggered manner, each light amount of the plurality of light emitting dots is measured using a photoelectric sensor. Light amount measuring method,
With relatively moves the photoelectric sensor relative to the plurality of light emitting dots, the at least two predetermined specific luminous dots of the plurality of luminous dots
Lighting control is performed individually and sequentially with the relative movement of the photoelectric sensor ,
Said photoelectric sensor receives light of the specific luminous dots, sequentially searched individually the position of the particular luminous dots,
The arrangement of the plurality of light-emitting dots is detected, and based on the detected arrangement data of the plurality of light-emitting dots, the photoelectric sensor is moved along a locus equidistant from two rows of the light-emitting dots.
And on the surface of the light-emitting object on which the plurality of light-emitting dots are arranged.
The plurality of light-emitting dots are sequentially turned on while alternately changing a row to emit light while being relatively moved at a certain distance in the vertical direction, and the light-emitting dots that are turned on at a predetermined distance from the light-emitting dots that are turned on. Are sequentially measured by the photoelectric sensor. Accordingly, the same effect as that of the first aspect of the invention can be obtained, and the light amount of the luminescent dots for two rows can be sequentially measured while moving along one trajectory, greatly reducing the time required for the measurement. Can be reduced.

According to a third aspect of the present invention, in the light emitting dot light amount measuring method according to the first or second aspect, the photoelectric sensor receives the light of the specific light emitting dot to obtain a maximum light amount. Or a predetermined amount close to the maximum
The position of the specific light-emitting dot is searched for by detecting a position at which a threshold light amount can be obtained . Therefore, the position of a specific light emitting dot can be detected with high accuracy.

[0022]

FIG. 1 is a diagram showing a light-emitting dot position search sequence in an embodiment of a light-emitting dot light amount measuring method according to the present invention. Arrows in the figure indicate relative movement of the photomultiplier tube 13 with respect to the vacuum fluorescent tube 1. FIG. 2 is a block diagram of a light quantity measuring device for realizing an embodiment of the light emitting dot light quantity measuring method according to the present invention. FIG. 3 is a diagram showing a light intensity detection value of a light dot by a photomultiplier tube. FIG. 4 is a diagram showing a processing procedure of a light emitting dot position search sequence shown in FIG.

In the figure, the same parts as those in FIG. 6 are denoted by the same reference numerals, and the description is omitted. 2, 11 is a computer, 12 is a sensor output amplifier, 14 is a lighting control circuit, 1
5 is a motor driver, 16 is a two-axis control motor, 17 is an X and Y stage, and 18 is a limit sensor. In FIG. 1, a plurality of light emitting dots 2 are fixedly arranged in a staggered manner with a predetermined relative positional relationship. No. 1 to No.
The sequence numbers up to (2n) are given. Out of the plurality of light emitting dots 2, two light emitting dot groups parallel to the X direction are hereinafter referred to as odd-numbered rows and even-numbered rows according to the odd-numbered and even-numbered order numbers of the light-emitting dots 2.

This embodiment is a light quantity measuring method for detecting the light quantity of each light emitting dot 2 of a vacuum fluorescent tube 1 constituting a line light source module for an optical printer. Before starting the light quantity measurement, the photomultiplier tube 13 is moved relative to the plurality of light emitting dots 2 and the light emitting dots 2 at both ends of the dot array forming the line light source, that is, the odd number of N
o. 1, No. The light emitting dots 2 assigned with the sequence number of (2n-1) are individually controlled to be lit, and the photomultiplier tube 13 receives these lights and sequentially searches the positions thereof.

At the time of light quantity measurement, the measurement start position is determined based on the searched position data of the light emitting dots 2 at both ends, and the photomultiplier tube 13 is relatively moved in accordance with the inclination of the dot arrangement, and The plurality of light emitting dots 2 are sequentially turned on and controlled in synchronization with each other, and a predetermined relative position based on the position of each lighted dot 2 as a reference, for example, each light emitting dot 2
At the center position of, the amount of light of each light-emitting dot 2 is sequentially measured by the photoelectric sensor.

As will be described later with reference to FIG. 2, in the light quantity measurement, a lighting control circuit 14 for lighting the light emitting dots 2 of the vacuum fluorescent tube 1 and an X, Y stage 1 on which the vacuum fluorescent tube 1 is mounted.
7. Automatic measurement by software using a two-axis control motor 16 for moving the X and Y stages 17, a motor driver 15, a sensor output amplifier 12 for amplifying the output of the photomultiplier tube 13, and a control computer 11 I do.

As shown in FIG. 1, the light emitting dots 2 are arranged linearly at the same pitch in both even and odd rows, and are patterned by a photomask. The accuracy (error) is on the order of tens of microns and can be ignored. Therefore, if the coordinates of the light emitting dots at both ends can be accurately detected, the coordinates of the light emitting dots 2 located between them can be obtained by interpolation calculation. Either end of either the odd column or the even column may be used, in which case the other end can be obtained by calculation. The coordinates for actually starting the light quantity measurement, the coordinates for ending the light quantity measurement, and the moving step of the photomultiplier tube 13 can also be obtained by calculation. The position search sequence of the center coordinates of the light emitting dots at both ends is executed by, for example, steps 1 to 10 as will be described later with reference to FIG. 4, but the outline will be described first.

The vacuum fluorescent tube 1 is attached to the measuring device so that the longitudinal direction of the row of the light emitting dots 2 substantially corresponds to the X direction. When the mounting is completed, before starting the light quantity measurement of each light emitting dot 2, the No. 1 which is the light emitting dot 2 at the left end. 1 is turned on, the relative position of the photomultiplier tube 13 with respect to the light emitting dot is moved in the X direction as shown in the figure, and the light amount is measured at a certain distance interval, for example, every several tens to several hundreds μ. As shown in FIG. 3, a light quantity detection value which is symmetrical with respect to the center is obtained. Here, to find the position to obtain the maximum amount of light, the X-coordinate x ₀ of the position and the X direction of the center coordinates.
Alternatively, two positions where the detected light amount is equivalent to a certain threshold value close to the maximum light amount are searched for, and the midpoint x ₀ of the X coordinates x ₁ and x ₂ of these positions is determined in the X direction. Center coordinates.

Next, the relative position of the photomultiplier tube 13 with respect to the light emitting dot 2 is moved in the Y direction as shown in the figure, and the light quantity is measured at certain distance intervals. At this time, a detection value having the same characteristics as in FIG. 3 is obtained, and the center coordinates in the Y direction can be detected. Next, No. 2 which is the light emitting dot 2 at the right end. (2n-1) is turned on. Photomultiplier tube 13
Is moved in the Y direction which is the longitudinal direction of the light source. (2
Similarly, for the light-emitting dot 2 of (n-1), the relative position of the photomultiplier tube 13 to the light-emitting dot is indicated by X and Y in the figure.
If the center coordinates in the X and Y directions are detected by moving
You can see the coordinates of the dots at both ends. If the coordinates of the dots at both ends are known, the dot arrangement can be detected. That is, the X and Y position coordinates of all the light emitting dots 2 and the inclination of the dot array can be calculated. Therefore, if two-axis control is performed at the time of measuring the amount of light based on the coordinates of the dots at both ends, the position of the dot arrangement is corrected at the time of measurement, and the deviation of the dot arrangement can be absorbed.

In the light quantity measuring device shown in FIG. 2, the vacuum fluorescent tube 1 is mounted on an X, Y stage 17 and is controlled to move relative to a fixed photomultiplier tube 13. The X, Y stage 17 is a stage that can move independently in the X, Y directions. Although it is simplified in the figure,
A stage in the other direction is mounted on one stage in the X and Y directions. The two-axis control motor 16 also includes two stepping motors that independently drive each stage in the X and Y directions, and drives a stage in the other direction mounted on one stage in the X and Y directions. The motor to be driven is also mounted on one of the stages. The computer 11 has a built-in controller board, drives each motor via a motor driver 15, and controls the X, Y stage 1
7 is controlled in two axes. The X and Y stages 17 are controlled by a limit sensor 18 to move within a movable range.

The computer 11 controls the power supply to the light emitting dots 2 of the vacuum fluorescent tube 1 through the lighting control circuit 14 and causes the specific light emitting dots 2 to emit light for a predetermined time. The spatially propagating light from the light emitting dot 2 enters the light receiving window of the photomultiplier tube 13 via the same optical system as in FIG. The photomultiplier 13 converts the incident light into light / current and outputs the converted light to the sensor output amplifier 12. The sensor output amplifier 12 performs current / voltage conversion and amplifies the light, and converts the light amount data into the data stored in the computer 11. Output to the / D conversion board. The computer 11 inputs the digitized light amount data, performs storage and calculation, and moves the X and Y stages 17 via the motor driver 15. In this way,
No. 2 which is the light emitting dot 2 at both ends. 1, No. (2n-
The detection of the center coordinates of 1) and the accurate detection of the light amount of all the light emitting dots 2 including the intermediate ones are automatically measured by software. Note that the vacuum fluorescent tube 1 may be fixed and the photomultiplier tube 13 may be attached to the X and Y stages 17 so that both can be relatively moved.

Returning again to FIG. 1 and referring to FIG. 1 and No. Specific processing of the position search sequence of the light emitting dots 2 at both ends of (2n-1) will be described. Processing is started by a measurement start command, and S2
In No. 1, the photomultiplier tube 13 is No. One light emitting dot 2 is relatively moved to the X direction search start position. At this time, the photomultiplier 13 follows the locus in FIG. In S22, No. is performed by the method described with reference to FIG. The center position in the X direction of one light emitting dot 2 is searched. The photomultiplier tube 13 takes a locus of relative movement in the X direction in FIG. In S23, No. 1
The center position of the light emitting dot 2 in the X direction is stored.

In S24, the photomultiplier tube 13 is set to N
o. One light emitting dot 2 is relatively moved to the center position in the X direction. The photomultiplier tube 13 takes a locus of relative movement in the -X direction in FIG. In S25, the photomultiplier tube 13 is set to No. The first light emitting dot 2 is relatively moved to the Y direction search start position. The photomultiplier 13 takes a locus of relative movement in the -Y direction in FIG. In S26, No. The center position in the Y direction of one light emitting dot 2 is searched. The photomultiplier tube 13 moves in the Y direction in FIG. In S27, No. The center position in the Y direction of one light emitting dot 2 is stored.

In S28, the photomultiplier tube 13 is set to N
o. The light emitting dot 2 at (2n-1) is relatively moved to the X direction search start position. At this time, the photomultiplier 13 follows the locus in FIG. In S29, No.
The center position in the X direction of the light emitting dot 2 of (2n-1) is searched. The photomultiplier tube 13 takes a locus in FIG. In S30, No. The center position of the (2n-1) light emitting dot 2 in the X direction is stored.

In S31, the photomultiplier tube 13 is set to N
o. The light emitting dot 2 (2n-1) is relatively moved to the center position in the X direction. The photomultiplier tube 13 takes a locus in FIG. In S32, the photomultiplier tube 13 is set to N
o. The light emitting dot 2 at (2n-1) is relatively moved to the Y direction search start position. The photomultiplier tube 13 takes a locus in FIG. In S33, No. (2n-
The center position in the Y direction of the light emitting dot 2 of 1) is searched. The photomultiplier tube 13 takes a locus indicated by a circle (10) in FIG. In S34, No. The center position in the Y direction of the (2n-1) light emitting dot 2 is stored.

According to the above-described search sequence, the Nos. 1, No. The exact X and Y coordinates of each of the (2n-1) light emitting dots 2 are detected. The above-described search sequence is an example, and the steps S24 and S25 and the steps S31 and S32 may be performed simultaneously.

Nos. At both ends of the odd-numbered row 1, No. (2n-
From the X and Y coordinates of the light emitting dot 2 in 1), the inclination of the odd and even rows of the plurality of light emitting dots 2 can be known, and the photomultiplier tube 13 is moved relative to the vacuum fluorescent tube 1 along this inclination. To move relatively. The light emitting dots 2 are sequentially turned on in synchronization with this movement, and the light receiving amounts from all the light emitting dots 2 are sequentially measured at predetermined intervals. By performing such a measurement, the light emission amount of each light emitting dot can be detected at an accurate position.

In the above description, an example has been described in which the coordinates of the light emitting dots 2 at both ends are detected. However, since the arrangement of the plurality of light emitting dots 2 on the X and Y planes may be understood, If the positions of two specific light emitting dots 2 determined in advance can be detected by searching, the arrangement of the light emitting dots 2 can be obtained by calculation.

In FIG. 2, a rotary stage that rotates on the X and Y planes is attached, and the inclination of the arrangement of the light emitting dots 2 is determined by rotating the vacuum fluorescent tube 1 with the rotary stage based on the coordinates of the light emitting dots 2 at both ends. By rotating the light-emitting dots 2 by a predetermined angle, the light amount measurement can be performed after the longitudinal direction of the arrangement of the light emitting dots 2 is completely matched with the X direction. However, the apparatus cost can be reduced by using the X-axis and Y-axis two-axis control without using the θ stage.

FIG. 5 is a diagram showing a specific example of the relative movement of the photomultiplier tube when measuring the light amount of each light-emitting dot in one embodiment of the light-emitting dot light amount measuring method of the present invention. FIGS. 5A to 5D are diagrams illustrating first to fourth examples of the movement trajectory. In the figure, the same parts as those in FIG. 6 are denoted by the same reference numerals, and description thereof will be omitted. The light emitting dots 2 are given sequence numbers as in FIG. 1, and the measurement points are indicated by black circles. 41-44
Is the movement locus of the photomultiplier tube.

In FIG. 5A, as indicated by the movement locus 41, the photomultiplier tube 13 is no. Starting from the center position of one light emitting dot 2, the photomultiplier tube 13 is relatively moved on a straight line passing through the center of the light emitting dots 2 in odd rows. When the center of the photomultiplier tube 13 is substantially at the center of each of the light emitting dots 2, the light emitting dots 2 are sequentially turned on so as to emit light for a predetermined period, and the light amount values during this light emitting period are integrated and averaged. Become

No., which is the last of the odd-numbered columns, When the light quantity measurement of the light emitting dot 2 of (2n-1) is completed, the photomultiplier 1
No. 3 is No. of the even-numbered column. Each light emitting dot 2 is relatively moved to the center of the light emitting dot 2 of (2n), and relatively moved on a straight line passing through the center of the light emitting dot 2 in the even-numbered row.
At the center position, the lighting of each light emitting dot 2 is sequentially controlled, and the light amount values are integrated and averaged.

In this example, the drive control is simple, but the brightness decreases due to the temperature that rises with the lapse of time of the light quantity measurement. As a result, the adjacent light emitting dots 2 in the odd and even rows are arranged.
There is a difference in luminance between the two, which easily affects the measurement of the amount of emitted light. As a modification of the first example, two photomultiplier tubes 13 are prepared for odd-numbered rows and even-numbered rows, and light-emitting dots 2 of odd-numbered rows and even-numbered rows are prepared.
It is also possible to move the upper part at the same time. However, since the photomultiplier tube 13 has a large difference in sensitivity between individual products, the error may be rather large.

In FIG. 5B, as indicated by the movement locus 42, the photomultiplier tube 13 is no. Starting from the center of one light emitting dot 2, odd rows and even rows are relatively moved alternately in accordance with the sequence number of the light emitting dots 2. When the center of the photomultiplier tube 13 is substantially at the center of each of the light emitting dots 2, the light emitting dots 2 are sequentially turned on so as to emit light for a predetermined period, and the light amount values during this light emitting period are integrated and averaged. Become The adjacent light emitting dots 2 are measured at almost the same amount of light, so that the influence of the temperature rise is small. However, in the control of the two-axis control motor 16 shown in FIG. Has a problem in measurement accuracy.

In FIG. 5C, as shown as a movement locus 43, the center of the photomultiplier tube 13 is relatively moved on a straight line equidistant from the odd and even rows.
The light amount of two rows of the light emitting dots 2 is measured by one linear movement. The center of the photomultiplier tube 13 is No. 1
And No. When it comes to the position of the middle point connecting the light emitting dots 2 of No. 2, Lighting control is performed so that one light emitting dot 2 emits light over a predetermined period, and the light amount values during this light emitting period are integrated and averaged. Subsequently, No. 2
Similarly, the light emitting dots 2 are controlled to light up, and the light amount values during this light emitting period are integrated and averaged. Similarly, the center of the photomultiplier tube 13 is 3 and No. 3
, No. 4, the midpoint connecting the light emitting dots 2 of No. 4 (2n-
1) and No. When it comes to the position of the midpoint connecting the light emitting dots 2 of (2n), the light emitting dots 2 are sequentially turned on so that the light emitting dots 2 emit light for a predetermined period, and the light amount values during the light emitting period are integrated and averaged. I do.

In this way, the photomultiplier tube 13 is relatively moved from the two rows of the light emitting dots 2 along the locus of the same distance, and the plurality of light emitting dots 2 are sequentially turned on while alternately changing the row to emit light. Illuminated dots 2
Each light emitting dot 2 lit at a position at a predetermined distance from
Are sequentially measured by the photomultiplier tube 13. Such measurement is possible because the sensitivity of the photomultiplier tube 13 depends only on the distance from the center as shown in FIG. 9C, and the sensitivity distribution characteristic is symmetric with respect to the center point. Because you have. Since the distance between the odd-numbered row and the even-numbered row is sufficiently shorter than the diameter d of the light receiving window 13a of the photomultiplier tube 13, even if the center of the light emitting dot 2 and the center of the photomultiplier tube 13 are displaced, The decrease is slight and a relative sensitivity of around 98% is obtained.

In this example, the time required for measurement is greatly reduced, and the measurement period is short. Therefore, even when the light quantity of the luminescent dots has a temperature dependence, the influence of the temperature rise during the measurement period is small. Yes.

FIGS. 5A to 5C show the photomultiplier tube 13.
Is relatively moved in the Y direction by a distance corresponding to the inclination. However, since the amount of movement in the Y direction is very small, it is difficult to move at a constant speed, and the accuracy can often be maintained without constantly moving.

Therefore, in FIG. 5D, as shown as a movement trajectory 44, the light emitting dot 2 is moved in the Y direction every time several dots are measured, so that the light quantity can be measured efficiently. did. FIG. 5 (D) is the same as FIG.
However, the same movement can be performed in FIG. 5 (A).

After detecting the light amounts of the plurality of light emitting dots 2 by using the light amount measuring method described above, the light emitting amount of each light emitting dot 2 becomes smaller than that of all the light emitting dots when used as a print head as in the prior art. The pulse width for driving each light emitting dot 2 is set so as to make the light emitting dots 2 uniform. By storing correction data for giving the set pulse width in the memory, the light amount of the light emitting dots 2 is corrected when the line light source is used as a print head.

In the above description, the photomultiplier tube 13 having a diffusion plate is used as a photoelectric sensor for measuring the amount of emitted light. However, as the distance from the center increases, the light receiving sensitivity of the light from the emitted dots 2 decreases. Then, the light quantity can be measured based on the same principle. Such a characteristic may be realized as an overall characteristic of the characteristic of the photoelectric conversion element itself and the characteristic of the optical system provided in front thereof.

The method of selecting a plurality of light emitting dots in the vacuum fluorescent tube for an optical printer may be performed by using only a plurality of anode electrodes, or by using both a plurality of anode electrodes and a plurality of grid electrodes for selecting a plurality of rows. Can be arbitrarily determined. The line light source for the optical printer, which is the object for measuring the light quantity, is not limited to the vacuum fluorescent tube 1, and a plurality of light emitting diodes (LEDs) and field emission devices based on the same principle as the field emission display (FED) are arranged in a line. Or a line light source in which a plurality of liquid crystal shutters for transmitting and blocking light from a light source that is constantly emitting light are arranged in a line. The number of rows is not limited to two, but may be one.
Or more rows, and R
When the correction data is written in the OM, the printing characteristics of each light emitting dot in the main scanning direction are made uniform as in the case of two rows.

The method of detecting the position of at least two specific light emitting dots in the above method of measuring the light amount of the light emitting dot is not limited to measuring the light amount, but generally, the inclination of each of the plurality of light emitting dots of the line light source, the light emission of each light emitting dot. It can be used to detect an arrangement state such as a dot position.

[0054]

According to the light emitting dot light quantity measuring method of the present invention, since the position of the light emitting dot can be accurately detected, the light quantity of the light emitting dot can be measured with high accuracy. After the measurement start command is executed, the position error is fully automatic and highly accurate, in order to absorb the assembly error in manufacturing and the deviation of the relative positional relationship between the light emitting dot and the photoelectric sensor due to attachment to the measuring device by software. Light quantity measurement can be performed, and highly accurate light quantity measurement can be performed. As a result, when the line light source is used as a print head, the light amount of the light emitting dots 2 can be corrected with high accuracy.

[Brief description of the drawings]

FIG. 1 is a diagram showing a light emitting dot position search sequence in an embodiment of a light emitting dot light amount measuring method according to the present invention.

FIG. 2 is a block diagram of a light quantity measuring device which realizes one embodiment of a light emitting dot light quantity measuring method according to the present invention.

FIG. 3 is a diagram showing a light intensity detection value of a light dot by a photomultiplier tube.

FIG. 4 is a diagram showing a processing procedure of a light emitting dot position search sequence shown in FIG.

FIG. 5 is a diagram showing a specific example of relative movement of a photomultiplier tube when measuring the light amount of each light emitting dot in one embodiment of the light emitting dot light amount measuring method of the present invention.

FIG. 6 is an external view of a vacuum fluorescent tube for an optical printer.

FIG. 7 is a schematic block diagram of a conventional printer light source and a diagram for explaining a conventional light amount correction method.

FIG. 8 is a perspective view of a light quantity measuring device for explaining a conventional light quantity measuring method.

FIG. 9 is a perspective view of a photomultiplier tube, a side view of a conventional light quantity measuring device, and a sensitivity distribution characteristic diagram of the photomultiplier tube.

[Explanation of symbols]

1 vacuum fluorescent tube, 2 light emitting dots, 11 computer, 12 sensor output amplifier, 13 photomultiplier tube, 1
4 lighting control circuit, 15 motor driver, 162 axis control motor, 17 X, Y stage, 18 limit sensor, 41-44 movement trajectory of photomultiplier tube, 51 photosensitive film, 71 condenser lens, 72 diffusion plate

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ identification code FIG03G 15/04 // H01J 31/15 (58) Field surveyed (Int.Cl. ⁷ , DB name) B41J 2/44 B41J 2 / 45 B41J 2/455 G01J 1/42 G01M 11/00 G03G 15/04 H01J 31/15

Claims (3)

(57) [Claims] 1. A method for measuring the amount of light of a plurality of light-emitting dots in a line light source having a plurality of light-emitting dots arranged in one or a plurality of rows using a photoelectric sensor, the method comprising: with relatively moves the photoelectric sensor relative to the plurality of luminous dots, at least two rough of the plurality of luminous dots
A specific light emitting dot determined in advance is moved relative to the photoelectric sensor.
Sequentially individually lighting control with dynamic, said photoelectric sensor receives light of the specific luminous dots, sequentially searched individually the position of the particular luminous dots,
A position detecting step of detecting an arrangement of the plurality of light emitting dots;
And the plurality of light emitting dots detected in the position detecting step .
Based on the arrangement data, the photoelectric sensor is relatively moved, and the plurality of light emitting dots are sequentially turned on and off, and the lighted dots are turned on at predetermined relative positions based on the positions of the lighted dots. From the light quantity measuring step of sequentially measuring the quantity of light by the photoelectric sensor.
A method for measuring the amount of light emitted from a luminescent dot. 2. A method for measuring the amount of light of a plurality of light-emitting dots in a line light source having a plurality of light-emitting dots arranged in two rows in a staggered manner using a photoelectric sensor. with relatively moves the photoelectric sensor relative to the plurality of luminous dots, at least two rough of the plurality of luminous dots
A specific light emitting dot determined in advance is moved relative to the photoelectric sensor.
Sequentially individually lighting control with dynamic, said photoelectric sensor receives light of the specific luminous dots, sequentially searched individually the position of the particular luminous dots,
A position detecting step of detecting an arrangement of the plurality of light emitting dots;
And the plurality of light emitting dots detected in the position detecting step .
Based on the layout data, the photoelectric sensor along equidistant trajectory from two rows of the luminous dots and the plurality of light emitting
A certain distance in the vertical direction to the surface of the light emission target where the dots are placed
The plurality of light-emitting dots are sequentially turned on while alternately changing the columns to emit light while moving relatively apart from each other, and the light amount of each of the light-emitting dots at a predetermined distance from each of the light-emitting dots is measured by the photoelectric control. A light amount measuring step of sequentially measuring with a sensor. 3. The photoelectric sensor according to claim 1, wherein the photoelectric sensor is configured to receive light of the specific light emitting dot and to obtain a maximum light amount or a maximum light amount.
The method according to claim 1, wherein the position of the specific light emitting dot is searched by detecting a position at which a light amount having a close predetermined threshold value can be obtained .