JPH0584991B2 - - 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 to 6) 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 rotation adjustment method for 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 a method in which, when performing so-called registration adjustment to arrange a solid-state image sensor used in a solid-state image sensor at a predetermined position in an imaging optical system, the repetition pitch is equal to the pixel pitch of the solid-state image sensor. Regarding the imaging output of a pair of repetitive patterns in corresponding areas on the left and right or top and bottom with the center of the screen in between, which is obtained by imaging a repeating pattern that repeats light and shade at a repeating pitch in a predetermined relationship using the solid-state imaging device, Rotation of the solid-state image sensor is performed by rotating the solid-state image sensor around the center so that the phases of a pair of beat components based on the difference between the pixel pitch of the image sensor and the repetition pitch match. Adjustments can be made with high precision through simple operations.

C. Prior Art Generally, 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 for each image pickup tube was performed by making a general position adjustment and then finely adjusting the position of the image pickup screen using the image pickup tube's deflection system.

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 7 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 registration to each image sensor with extremely high precision. 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, ±RY direction, and ±RZ It is necessary to ensure registration on the order of 1 μm in six axes of the direction, and conventionally, the above-mentioned registration adjustment has required a great deal of effort and time.

Therefore, the method of the present invention makes it possible to perform the registration error in the RZ direction, that is, the rotation adjustment of the solid-state image sensing device, with high accuracy with simple operations when performing the registration adjustment in the six-axis directions described above. The purpose is to

E Means for Solving the Problems In order to solve the above-mentioned problems, the rotation adjustment method for a solid-state image sensor according to the present invention deals with the left and right sides or the top and bottom of the screen across the imaging screen of the solid-state image sensor. The solid-state imaging device captures an image in which a pair of repeating patterns of light and shade are repeated in the horizontal or vertical direction, and the repeating pitch thereof has a predetermined relationship with the pixel pitch in the horizontal or vertical direction of the solid-state imaging device. detecting a pair of beat components based on the difference between the pixel pitch of the solid-state image sensor and the repeating pitch for the image pickup output of a pair of repeating patterns of portions corresponding to the left and right or top and bottom of the screen;
The solid-state imaging device is characterized in that the solid-state imaging device is rotated about the center and the rotation is stopped at a position where the phases of the pair of beat components match.

F Effect In the rotation adjustment method for a solid-state image sensor according to the present invention, a pair of repeating patterns that repeat shading in the horizontal or vertical direction are applied to portions corresponding to the left and right or top and bottom of the image pickup screen of the solid-state image sensor, respectively. The imaging output obtained by capturing an image with the solid-state image sensor, the repetition pitch of which has a predetermined relationship with the pixel pitch in the horizontal or vertical direction of the solid-state image sensor, has a repetition pitch that is equal to the pixel pitch in the horizontal or vertical direction. Contains a beat component based on the difference in pitch. The phase of the beat component above is
It changes depending on the registration error in the above-mentioned ±X direction, arrow ±Y direction, and ±RZ direction.
Regarding the imaging output of a pair of repeating patterns in the left and right or top and bottom corresponding parts across the center of the screen obtained by the solid-state image sensor, a pair of repeating patterns based on the difference between the pixel pitch of the solid-state image sensor and the repeat pitch are determined. By rotating the solid-state imaging device about the center so that the beat components match in phase, rotation adjustment of the solid-state imaging device can be performed with high precision with a simple operation.

G Example Hereinafter, an example of the rotation adjustment method for a solid-state image sensor according to the present invention will be described in detail with reference to the drawings.

The embodiment shown in FIGS. 1 to 6 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 generator 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, and is also supplied to a high resolution monitor 46 via a video signal processing circuit 45, and further via a digitizer 47 to a micro It is supplied to the computer 48.

G-2 Configuration of Test Chart for Registration Measurement As schematically shown in FIG. ±Δ ...Equation 1 (Here, Δ is set as Δ=τc・τp/τo, where τo is the effective image area size in the pixel arrangement direction.) Repetition with the relationship of Equation 1: The image of the repeating pattern PT that repeats shading at pitch 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, two vertical striped repeating patterns PTah, PTbh, which are arranged symmetrically across the horizontal center line Lsh and parallel to each other, and two repeating patterns PTah, PTbh, which are arranged symmetrically across the vertical center line Lsv and parallel to each other. horizontal striped repeating pattern PTav,
PTbv is used.

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

In this embodiment, 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 ±Z direction, ±RX, ±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 the driving state, and the repetitive pattern of the test chart 10 for measuring the strain is imaged, and the imaging output obtained by each of the CCD image sensors 31r, 31g, and 31b is shown in FIG. The respective position adjustment jigs 40r, 40g,
40b and follow the steps below to select each of the above CCDs.
Six-dimensional alignment is performed for the image sensors 31r, 31g, and 31b.

In this embodiment, each CCD image sensor 31
First, back focus adjustment and tilt adjustment are performed for r, 31g, and 31b.

The back focus adjustment and tilt adjustment are performed using the beats included in the imaging output signal obtained by imaging the repeating pattern of the registration measurement test chart 10 using the CCD image sensors 31r, 31g, and 31b through the master lens 20. The amplitude of the component is determined by the back focus and the tilt amount of the solid-state image sensor, that is, the registration error in the above-mentioned ±Z direction and ±RX, ±RY direction, that is, the back focus of the imaging optical system and each CCD image sensor 31r, 31.
g, varies depending on the amount of tilting of 31b, and each of the above
Since the maximum value is reached when the CCD image sensors 31r, 31g, and 31b are in the just-focus position, the beat component is detected by the oscilloscope 4.
This is performed by operating the position adjustment jigs 40r, 40g, and 40b while observing the waveform in step 4 to detect the position where the amplitude of the beat component is maximum.

Next, for each CCD image sensor 31r, 31g, 31b whose imaging plane has been determined by the backfocus adjustment and tilt adjustment, the registration measurement test chart 10 is shown.
Using the horizontal and vertical center lines Lsh and Lsv, coarse horizontal and vertical center adjustment and rotation adjustment are performed.

In other words, since the picture element located at the center of the imaging surface of the CCD image sensor 31 is fixed,
A cross-shaped reference image centered on this picture element is displayed on the screen of the high-resolution monitor 46 as shown by the solid line in FIG. CCD
Horizontal and vertical directions of the registration measurement test chart 10 captured by the image sensors 31r, 31g, and 31b and monitored on the screen of the high-resolution monitor 46, for example, as shown by broken lines in FIG. The position adjustment jigs 40r, 40g, and 40b are operated so that the images of the center lines Lsh and Lsv coincide with the cross-shaped reference image.

With this adjustment operation, each CCD image sensor 3
The horizontal and vertical centers and rotations of CCD image sensors 1r, 31g, and 31b are roughly adjusted to approximately ±3 μm, and each CCD image sensor 31r,
The registration of 31g and 31b is adjusted to within 1/2 pixel pitch.

In the rotation adjustment operation, the above-mentioned imaging output signal obtained by imaging the repeating pattern of the registration measurement test chart 10 by each CCD image sensor 31r, 31g, 31b via the master lens 20 is The image output of each central portion Cu, Cd of two vertical striped repeating patterns PTah, PTbh, which are arranged symmetrically across the horizontal center line Lsh and parallel to each other, schematically shown in FIG. ,4
2g and 42b. Each beat component included in the image output of the central portions Cu and Cd of both sides has a phase difference corresponding to the registration error in the ±RZ direction, that is, the rotation error of the CCD image sensor 31. There is.

Therefore, while observing the waveforms of each beat component included in the image output of the central portions Cu and Cd of both sides using the oscilloscope 44 as shown in FIG.
to the position where the phases of the respective beat components match each other.
Rotation adjustment is performed by rotating 31b.

In this embodiment, each CCD image sensor 31
r, 31g, and 31b, first, the amplitude of the beat component included in the center AS imaging output of the repeat pattern PTsh in the form of vertical stripes that repeats shading along the horizontal center line Lsh of the registration adjustment test chart 10. The back focus adjustment is performed using the change in the registration adjustment test chart 10, and the vertical striped repeating pattern PTsh of the registration adjustment test chart 10 is arranged symmetrically across both sides Ba and Bb and the horizontal center line Lsh. Two parallel vertical striped repeating patterns PTah,
Using changes in the amplitude of the beat components included in the imaging outputs of each central part Cu and Cd of PTbh, horizontal and vertical tilt adjustment is performed. Repeated pattern of Cu, Cd and horizontal stripes
By using the change in the phase of the beat component included in the imaging output of the central portions Da and Db of PTav and PTbv, the rotation adjustment and the center adjustment in the horizontal and vertical directions can be performed in the six axes mentioned above. All 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, in the solid-state imaging device rotation adjustment method according to the present invention, the solid-state imaging device rotates the imaging screen of the solid-state imaging device at the portions corresponding to the left and right or top and bottom of the screen. The solid-state image sensor captures an image of a pair of repeating patterns, each of which repeats light and shade in the horizontal or vertical direction, the repeating pitch of which has a predetermined relationship with the pixel pitch of the solid-state image sensor in the horizontal or vertical direction. Regarding the obtained imaging output, the pixel pitch of the solid-state imaging device and the repetition pitch included in the imaging output of a pair of repeating patterns in the left and right or top and bottom corresponding parts across the center of the screen obtained by the solid-state imaging device. so that the phases of the pair of beat components match based on the difference between
By rotating the solid-state image sensor around the center, rotation adjustment of the solid-state image sensor can be performed with high accuracy with simple operations, and the intended purpose can be fully achieved.

[Brief explanation of the drawing]

1 to 6 are screens showing an embodiment of the 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. and
Figure 2 shows the test pattern of the test chart for registration measurement in the above example and the CCD.
FIG. 3 is a schematic diagram for explaining the relationship with the pixel arrangement of the image sensor; FIG. 3 is a schematic diagram showing the configuration of the test chart for registration measurement used in the above embodiment; FIG. 5 is a waveform diagram showing beat components included in the imaging output obtained by imaging the test pattern of the test chart for registration measurement with a CCD image sensor, and FIG. 5 shows the registration of the CCD image sensor in the above example. FIG. 6 is a schematic diagram for explaining the coarse adjustment operation, and FIG. 6 is a waveform diagram showing beat components used in the rotation adjustment operation of the CCD image sensor in the above embodiment. FIG. 7 is an external perspective view of a CCD image sensor for explaining the direction of adjustment operation for 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 pair of repeating patterns that repeat shading in the horizontal or vertical direction in portions corresponding to the left and right or top and bottom of the screen across the center of the imaging screen of a solid-state image sensor, the repeating pitch being is in a predetermined relationship with the pixel pitch in the horizontal or vertical direction of the solid-state imaging device, and the imaging output of a pair of repetitive patterns corresponding to the left and right or top and bottom of the screen is as described above. A pair of beat components based on the difference between the pixel pitch of the solid-state image sensor and the repetition pitch is detected, and the solid-state image sensor is rotated about the center to a position where the phases of the pair of beat components match. A method for adjusting the rotation of a solid-state image sensor, the rotation of which is stopped.