JPH0584990B2 - - Google Patents

Description

[Detailed description of the invention] Hereinafter, the present invention will be explained in the following order.

A. Industrial field of application B. Summary of the invention C. Prior art D. Problems to be solved by the invention E. Means for solving the problems F. Effects G. Example G-1 Configuration of registration adjustment device (first (See figure) G-2 Configuration of test chart for registration measurement (See Figures 2 and 3) G-3 Adjustment operation procedure (See Figures 4 and 5) H Effect of the invention A Industrial Field of Application The present invention relates to a charge-coupled device (CCD) used as an image sensor in a solid-state imaging device.
The present invention relates to a method for measuring the amount of tilting of a solid-state image sensor, which is applied when performing so-called registration adjustment, etc., in which a solid-state image sensor such as a charge coupled device is placed at a predetermined position in an imaging optical system.

B. Summary of the Invention The present invention provides that when performing so-called registration adjustment, etc., in which a solid-state image sensor used in a solid-state image sensor is placed at a predetermined position in an imaging optical system, the repeat pitch is the same as the pixel pitch of the solid-state image sensor. Regarding the imaging output obtained by imaging a repeating pattern that repeats shading at a repeating pitch in a predetermined relationship with the solid-state imaging device, the picture elements of the solid-state imaging device are moved in the optical axis direction of the imaging lens of the solid-state imaging device. By performing the operation of detecting the position where the beat component due to the difference between the pitch and the above-mentioned repeating pitch is maximum on the center of the image capture screen and the portions corresponding to the left and right or top and bottom of the screen across the center, The amount of tilting of the solid-state image sensor can be calculated with high accuracy from the measurement output at each of the above positions.

C. PRIOR TECHNOLOGY In general, in a color imaging device, imaging light is separated into multiple color components using a color separation system, and a subject image of each color component is captured using a solid-state image sensor such as a CCD or an imaging tube. from each imaging output
It is designed to form and output standard color television signals such as the NTSC system. In a color imaging device using a plurality of image sensors, it is necessary to reliably maintain a state in which subject images of each color component captured by each image sensor are superimposed, that is, so-called registration adjustment is performed accurately.

In the conventional so-called three-tube color video camera, a three-color separation prism and three image pickup tubes are mechanically attached to a housing made of die-casting, etc., and the output signal from a test chart, etc., is transmitted to the machine. Registration adjustment of each image pickup tube was performed by adjusting the position of each image pickup tube, and then finely adjusting the position of the image pickup screen using the deflection system of the image pickup tube.

In contrast to such a three-tube color video camera, a solid-state color imaging device that uses a solid-state imaging device such as a CCD as an image sensor cannot electrically adjust the imaging screen position like an imaging tube. A holder made of iron or the like is bonded to each solid-state image sensor that captures an object image of each color component, and a holder is also bonded to each light emitting part of a color separation prism of a color separation system.
For each image sensor, as shown in Figure 6 with arrows indicating the adjustment directions, (1) Horizontal center (arrow ±X direction) adjustment (2) Vertical center (arrow ±Y direction) adjustment ( 3) Back focus (arrow ±Z direction) adjustment (4) Horizontal tilt (arrow ±RX direction) adjustment (5) Vertical tilt (arrow ±RY direction) adjustment (6) Rotation (arrow ±RZ direction) adjustment After performing registration adjustment in the six-axis directions, each solid-state image sensor was attached and fixed to each exit surface of the color separation prism by thermally welding each holder by soldering or the like.

D Problems to be Solved by the Invention In general, solid-state image sensors such as CCDs cannot electrically adjust the imaging screen position like an image pickup tube, so in a color imaging device using multiple solid-state image sensors, It is necessary to mechanically maintain the registration of each image sensor with extremely high accuracy. In particular, in solid-state color imaging devices that employ the so-called spatial pixel shifting method to achieve high resolution, the above-mentioned ±X direction, arrow ±Y direction, ±Z direction, ±RX direction, ±RY direction, and ± RZ
It is necessary to secure registration on the order of 1 μm in the six axes of the direction.
The above-mentioned registration adjustment requires a great deal of effort and time.

Therefore, the method of the present invention measures the registration error in the RX and RY directions, that is, the amount of tilting of the solid-state image sensor, with high precision using simple operations when performing the registration adjustment in the six-axis directions. It is an object of the present invention to make it possible to perform tilt adjustment of a solid-state image pickup device with a simple operation and with high accuracy.

E. Means for Solving the Problems In order to solve the above-mentioned problems, in the method for measuring the amount of tilting of a solid-state image sensor according to the present invention, in order to solve the above-mentioned problems, The image is a repeating pattern that repeats shading in the horizontal or vertical direction on the left and right or top and bottom corresponding parts of the image sensor, and the repeating pitch has a predetermined relationship with the horizontal or vertical pixel pitch of the solid-state image sensor. The solid-state image pickup device captures an image, and first, among the image pickup output of the repetitive pattern corresponding to the center of the screen, the beat component based on the difference between the pixel pitch of the solid-state image pickup device and the repeat pitch is detected. The image sensor is moved in the optical axis direction of the imaging lens, and the position where the detection output is maximum is set as the initial position, and then,
The solid-state imaging device is moved in the optical axis direction of the imaging lens while detecting the beat component for the imaging output of one of the repeating patterns of the portions corresponding to the left and right or top and bottom of the screen, and the second detection output is maximized. A first measurement output is obtained by measuring the amount of movement between the position of and the initial position, and a beat component is further detected for the imaging output of the other repeating pattern of the portion corresponding to the left and right or top and bottom of the screen. while moving the solid-state imaging device in the optical axis direction of the imaging lens and measuring the amount of movement between the third position where the detection output is maximum and the initial position or the second position. The present invention is characterized in that the amount of tilting is calculated from the first and second measured outputs.

F Effect In the method for measuring the amount of tilting of a solid-state image sensor according to the present invention, the central part of the imaging screen of the solid-state image sensor and the parts corresponding to the left and right or top and bottom of the screen across the center are shaded in the horizontal or vertical direction, respectively. The image pickup output obtained by capturing an image with the solid-state image sensor, which is a repetitive pattern in which the repeating pitch has a predetermined relationship with the pixel pitch in the horizontal or vertical direction of the solid-state image sensor, includes the above-mentioned image. A beat component based on the difference between the basic pitch and the repeated pitch is included. The amplitude of the beat component changes depending on the back focus of the imaging optical system and the tilt amount of the solid-state image sensor, that is, the registration error in the ±Z direction, ±RX, and ±RY directions. It changes depending on the registration error in the five axes of the above-mentioned ±X direction, arrow ±Y direction, ±RZ, ±RY direction, and ±RZ direction.
Regarding the imaging output obtained by imaging with the solid-state imaging device, the beat component due to the difference between the pixel pitch of the solid-state imaging device and the repetition pitch is maximized by moving the imaging lens of the solid-state imaging device in the optical axis direction. By performing the operation to detect the position of Can be calculated with high accuracy.

G Example Hereinafter, an example of the method for measuring the tilt amount of a solid-state image sensor according to the present invention will be described in detail with reference to the drawings.Hereafter, an example of a test chart for measuring the registration of a solid-state image sensor according to the present invention will be described in detail. will be explained in detail according to the drawings.

The embodiment shown in FIGS. 1 to 5 is a three-plate type
The present invention is applied to a registration adjustment device for adjusting the registration of a CCD color video camera.

G-1 Configuration of Registration Adjustment Device The registration adjustment device in this embodiment, as schematically shown in FIG. A chart 10 is arranged in front of a master lens 20. The imaging light of the test pattern by the registration measurement test chart 10 is transmitted to the master lens 20.
is guided to a color separation prism 30 of a three-plate CCD color video camera, and this color separation prism 30 converts the imaging light into three primary color lights R, G, and B, that is, red component light R, green component light G, and blue component light. B
The three CCD image sensors 31r,
31g and 31b are irradiated.
Each of the above CCD image sensors 31r, 31g, 3
1b is attached to position adjustment jigs 40r, 40g, and 40b that perform six-dimensional positioning, respectively. And each of the above CCD image sensors 3
1r, 31g, and 31b are CCDs that operate based on the reference signal provided by the reference signal generator 50.
It is driven by a drive circuit 51 and images an image, that is, a test pattern, using the imaging light of each color component separated by the color separation prism 30. Each of the above
Each image pickup output obtained by the CCD image sensors 31r, 31g, and 31b is transmitted to a preamplifier 4.
From 1r, 41g, 41b, each gate circuit 42r,
It is supplied to the matrix circuit 43 via 42g and 42b. Here, each of the gate circuits 42r, 4
2g and 42b are supplied with gate pulses generated by a gate pulse generating circuit 52 that operates based on the reference signal.

The image output signal obtained by the matrix circuit 43 is supplied to an oscilloscope 44 for wave observation, is supplied to a high resolution monitor 46 via a video signal processing circuit 45, and is further supplied to a microcomputer via a digitizer 47. 48.

G-2 Configuration of Test Chart for Registration Measurement As schematically shown in FIG. ±Δ...Equation 1 (Here, Δ is set to Δ=τc・τp/τo, where τo is the effective image area size in the pixel arrangement direction.) The repetition pitch satisfies the relationship of Equation 1: The image of the repeating pattern PT that repeats shading with τp is shown above.
It is designed to be applied to a CCD image sensor 31.

As schematically shown in FIG. 3, the test chart 10 for registration measurement in this embodiment has a test pattern that is a repeating vertical striped pattern that repeats shading along the horizontal center line Lsh. PTsh and two parallel lines arranged symmetrically across the horizontal center line Lsh.
The book's vertical striped repeating patterns PTah, PTbh,
Two horizontal striped repeating patterns PTav that are symmetrically arranged across the vertical center line Lsv and parallel to each other,
PTbv is used.

Here, each of the above vertical striped repeating patterns
PTsh, PTah, PTbh are the above-mentioned first
It is formed to repeat shading at a repetition pitch τph, which is in the relationship of the formula. Further, the horizontal striped repeating patterns PTav and PTbv are formed to repeat shading at a repeating pitch τpv that has the relationship expressed by the first equation above with respect to the vertical pixel pitch τcv of the CCD image sensor 31.

In this example, one test chart can be used in common to perform registration measurements for CCD image sensors with two types of pixel arrays that comply with CCIR and EIA standards. Two types of test patterns corresponding to CCIR and EIA standards are provided side by side.

The imaging output obtained by the CCD image sensor 31, which is irradiated with the imaging light of the test pattern by the test chart 10 for registration measurement as described above, is the difference between the repetition pitch τp of the repetition pattern PT and the pitch of each pixel τc. A moiré pattern based on the above repeating pattern is generated.
The signal level changes as shown in FIG. 2 depending on the relative position of PT and each picture element S. In other words, the imaging output for the horizontal repeating pattern PTh is:
As shown in FIG. 4, Δ beat components are included in one horizontal scanning period (1H).

The beat component included in the imaging output signal obtained by imaging the repeating pattern of the test chart 10 for registration measurement with the CCD image sensor 31 has an amplitude that is the back focus of the imaging optical system and the tilt amount of the solid-state imaging device. In other words, the above-mentioned ±Z direction, ±RZ, ±RY
The phase changes depending on the registration error in the direction, and its phase also depends on the center position and rotation of the solid-state image sensor, that is, the registration error in the above-mentioned ±X direction, arrow ±Y direction, and ±RZ direction. and change.

G-3 Adjustment operation procedure Therefore, in this embodiment, each of the position adjustment jigs 40r, 40 of the registration adjustment device is
Each CCD image sensor 3 attached to g, 40b
1r, 31g, and 31b are in a driving state, the repetitive pattern of the test chart 10 for measuring the strain is imaged, and each beat component of the imaging output obtained by each of the CCD image sensors 31r, 31g, and 31b is captured using the oscilloscope. 4
4 while performing waveform observation using the microcomputer 48 or waveform analysis using the microcomputer 48, operating each of the position adjustment jigs 40r, 40g, and 40b,
Each CCD image sensor 31r, 31g, 31b
6-dimensional alignment is performed.

In this embodiment, each CCD image sensor 31r, 31g, 3
Regarding the imaging output signal obtained by imaging the repeating pattern of the test chart 10 for registration measurement using 1b, first, vertical stripes of repeating shading are detected along the horizontal center line Lsh schematically shown in FIG. 3 above. The image output of the central part AS of the repeated pattern PTsh is output to each gate circuit 4.
It is selectively taken out by 2r, 42g, and 42b. That is, the image output at the center of the imaging screen is extracted, which is less affected by the axial aberration and chromatic magnification aberration of the imaging optical system. The amplitude of the beat component included in the image output of the central portion AS changes depending on the registration error in the ±Z direction, that is, the back focus of the imaging optical system, and the amplitude of the beat component included in the image output of the central portion AS changes depending on the registration error in the ±Z direction, that is, the back focus of the imaging optical system. It is maximum when is at the just focus position.

Therefore, while observing the waveform of the beat component included in the image output of the central portion AS using the oscilloscope 44, each position adjustment jig 40r,
40g, 40b to move each CCD image sensor 31r, 31g, 31b to the position where the partial amplitude of the antinode of the beat component is maximum.
g, 31b to the just-focus position, that is, back-focus adjustment is performed.

In the back focus adjustment, the aperture of the imaging optical system is opened to make the depth of focus shallow, and the registration measurement test chart 10 is measured by each CCD image sensor 31r, 31g, 31b via the master lens 20. Take an image.

And each CCD image sensor 31r, 31
g, 31b, the horizontal center line Lsh of the registration measurement test chart 10
Both ends Ba and Bb of the vertical striped repeating pattern PTsh that repeats shading along ,Cd
Use the following to adjust the tilt in the horizontal and vertical directions.

In the horizontal tilt adjustment operation, regarding the imaging output signal obtained by imaging the repeating pattern of the registration measurement test chart 10 with each CCD image sensor 31r, 31g, 31b via the master lens 20,
Horizontal center line schematically shown in Figure 3 above
Image outputs on both sides Ba and Bb of the vertical striped repetitive pattern PTsh that repeats shading along Lsh are selectively taken out by each gate circuit 42r, 42g, and 42b.

The amplitude of the beat component included in the image output of both sides Ba and Bb is determined by each CCD image sensor 3.
There is a level difference depending on the amount of horizontal tilting of 1r, 31g, and 31b, that is, the above-mentioned registration error of ±RX.

Therefore, while observing the waveform of the beat component shown in FIG. 4, which is included in the image output of both sides Ba and Bb, using the oscilloscope 44, the position adjustment jigs 40r, 40g, and 40b are operated. , each CCD image sensor 31r, 31g, until the position where the partial amplitude of the antinode of the beat component is maximum.
31b is moved in parallel to create the above repeating pattern.
Just focus positions Pa and Pb of each CCD image sensor 31r, 31g, and 31b with respect to both sides Ba and Bb of PTsh are detected.

Then, the above-mentioned back focus adjusted
As shown in FIG. 5, with the position of the CCD image sensor 31 as the initial position Po, the amount of movement from the initial position Po to the just focus positions Pa and Pb is measured to obtain the measurement outputs Δa and Δb. , the amount of tilt of the CCD image sensor 31 is calculated from each measurement output Δa, Δb, and the tilt adjustment is performed by repeating the adjustment operation two or three times so that Δa=Δb=0.

Note that in the above tilt adjustment, |Δa|=|Δb| is not necessarily achieved due to field curvature, but it can be converged by repeatedly performing adjustment.

In addition, vertical tilt adjustment operations are performed on each CCD.
The test chart 10 for measuring the registration using the image sensors 31r, 31g, and 31b.
Regarding the imaging output signal obtained by imaging the repeating pattern of While observing the waveform of the beat component included in the output using the oscilloscope 44, the position adjustment jigs 40r, 40g, and 40b are operated in the same manner as the horizontal tilt adjustment described above. .

Each CCD image sensor 31r, 31g,
The imaging plane of 31b is determined.

In this embodiment, after the tilt adjustment described above, each of the CCD image sensors 31r, 31g,
31b, the vertical striped repeating pattern of the test chart 10 for registration measurement described above.
Rotation adjustment and horizontal and vertical rotation adjustment are performed by using changes in the phase of the beat components included in the imaging outputs of the central parts Cu and Cd of PTah and PTbh and the central parts Da and Db of the horizontal striped repeat patterns PTav and PTbv. By adjusting the center of the direction, the above 6
All axial registration adjustments can be completed with extremely high precision.

H. Effects of the Invention As is clear from the description of the embodiments described above, the method for measuring the amount of tilting of a solid-state image sensor according to the present invention can be used to The above-mentioned solid-state image sensor captures an image that has a repeating pattern of repeating shading in the horizontal or vertical direction, and whose repeat pitch has a predetermined relationship with the pixel pitch in the horizontal or vertical direction of the above-mentioned solid-state image sensor. Regarding the imaging output obtained by imaging, move it in the optical axis direction of the imaging lens of the solid-state imaging device to determine the position where the beat component based on the difference between the pixel pitch of the solid-state imaging device and the repetition pitch is maximum. By performing the operation to detect the center of the imaging screen and the parts corresponding to the left and right or top and bottom of the screen across the center, the amount of tilt of the solid-state image sensor can be determined with high accuracy from the measurement output at each of the above positions. can be calculated, and the intended purpose can be fully achieved.

[Brief explanation of the drawing]

1 to 5 are drawings showing an embodiment of a registration adjustment device to which the present invention is applied, and FIG. 1 is a block diagram schematically showing the configuration of the registration adjustment device of this embodiment. 2 is a schematic diagram for explaining the relationship between the test pattern of the test chart for registration measurement in the above embodiment and the pixel arrangement of the CCD image sensor, and FIG. FIG. 4 is a schematic diagram showing the configuration of the test chart for registration measurement, and FIG. 4 shows the test pattern of the test chart for registration measurement.
It is a waveform diagram showing a beat component included in the imaging output obtained by imaging with a CCD image sensor,
FIG. 5 is a schematic diagram for explaining the tilt adjustment operation of the CCD image sensor in the above embodiment. FIG. 6 is an external perspective view of a CCD image sensor for explaining the direction of adjustment operation in general registration adjustment. 10...Test chart, 20...Master lens, 30...Color separation prism, 31r, 31g, 3
1b...CCD image sensor.

Claims (1)

[Scope of Claims] 1. A repeating pattern in which shading is repeated in the horizontal or vertical direction at the center of the imaging screen of a solid-state image sensor and at portions corresponding to the left and right or top and bottom of the screen across the center, and An image whose repeating pitch has a predetermined relationship with the pixel pitch in the horizontal or vertical direction of the solid-state imaging device is captured by the solid-state imaging device, and first, among the imaging outputs of the repeating pattern corresponding to the center of the screen, the above-mentioned image is captured by the solid-state imaging device. The solid-state imaging device is moved in the optical axis direction of the imaging lens while detecting a beat component based on the difference between the pixel pitch of the solid-state imaging device and the repetition pitch, and a position where the detection output is maximum is set as an initial position. Next, the solid-state image sensor is moved in the optical axis direction of the imaging lens while detecting the beat component of the imaging output of one of the repetitive patterns of the portions corresponding to the left and right or top and bottom of the screen, so that the detection output is maximized. A first measurement output is obtained by measuring the amount of movement between the second position and the initial position, and further, regarding the imaging output of the other repeating pattern of the portion corresponding to the left and right or top and bottom of the screen. While detecting the beat component, the solid-state imaging device is moved in the optical axis direction of the imaging lens, and the amount of movement between the third position where the detection output is maximum and the initial position or the second position is measured. A method for measuring the amount of tilting of a solid-state image sensor, comprising: obtaining a second measurement output, and calculating the amount of tilting from the first and second measurement outputs.