JPH08125915A - Method for automatically adjusting resolution of image pickup element - Google Patents

Abstract

PURPOSE: To automatically adjust a highly accurate line camera to a target resolution by storing characteristics relating to an image pickup element and the target value of a mark and automatically performing adjustment so as to equalize the detected value of the mark and the target value. CONSTITUTION: By using a test pattern TP on a glass substrate G for the adjustment, the resolution to be the target of the line camera Ca, the width of a marking area MA and the data of the resolution of the line camera Ca are registered beforehand. An automatic focusing device F is in normal constitution, drives a lens L by a motor M1 based on video signals from the line camera Ca and automatically adjusts a focus. A phase controller S inputs the video signals and horizontal synchronizing signals HD and measures the image photographing time of the MA and the image photographing time of the non marking area of the TP. Then, based on the duty factor of the photographing time, so as to equalize the detected value of the mark and the target value, the motor M2 is driven and a distance between the line camera Ca and the MA is automatically set.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resolution automatic adjustment method for automatically performing fine adjustment of the resolution of an image pickup device.

[0002]

2. Description of the Related Art In image processing, for example, a one-dimensional CCD (Charge Coupled Device) as an image pickup device for capturing an image used in an automatic production facility or the like.
e: There is a line camera (line sensor) using a solid-state image sensor, and when adjusting the resolution of such a line camera, conventionally, an instrument such as a scale is placed on the subject,
It was common to adjust by observing the scale and fix the line camera.

[0003]

[Problems to be Solved by the Invention]
For line cameras with more than 0 pixels, the resolution is 100
There is no display that displays 2000 pixels at the same time even when viewed visually. That is, since the image is usually compressed and displayed, the resolution is reduced to 1/2 to 1/4. Therefore, adjustment of the resolution of such a line camera has conventionally required a considerable amount of time and effort.

An object of the present invention is to provide a method for automatically adjusting the resolution of an image pickup device that captures an image, and in particular, by using a high-precision line camera having more than 2000 pixels, the position of the line camera is automatically moved to a target resolution. Yes, and
It is to simplify the control system so that the cost can be reduced.

[0005]

In order to solve the above problems, the present invention provides an image pickup device comprising an image pickup device for capturing an image and a phase control device for adjusting the resolution of the image pickup device. The control device stores the target value of the mark provided in advance on the subject and the characteristics relating to the image sensor,
The image sensor compares the detected value of the mark provided on the subject with the previously stored target value, and the image sensor and the image sensor are arranged so that the detected value becomes equal to the target value. It is characterized by an automatic resolution adjustment method for an image sensor, which automatically adjusts the distance from the mark provided on the subject.

In the phase control device, for example, a target resolution x of the image sensor, a width g of the mark, a resolution d of the image sensor, and an image capturing time Tb of the mark captured by the image sensor. From the shooting time Tc of the non-marked portion, the actual resolution Δx is calculated by the following equation Δx
= {(Tc / Tb) +1} (g / d), and when the value of the actual resolution Δx is larger than the target resolution x, bring the image sensor close to the subject, and When the value of the actual resolution Δx is smaller than the target resolution x, the image sensor is controlled to be moved away from the subject.

Further, in the phase control device, for example, from the driving frequency f of the image pickup device, or the resolution d and the horizontal period Ta of the image pickup device, the width g of the mark, and the image capturing time Tb of the mark, the target is determined. The mark width Δg corresponding to the desired resolution is calculated based on the following equation Δg = Tb · f or Δg = Tb (d / Ta), and the mark width g is equal to the target mark width Δg. The distance between the image sensor and the subject is controlled so that

Alternatively, in the phase control apparatus, for example, a mark width Δg corresponding to a target resolution is set in advance, and when the target mark width Δg is larger than the mark width g, When the image pickup device is moved away from the subject and when the target mark width Δg is smaller than the mark width g, the image pickup device is controlled so as to approach the subject.

[0009]

According to the present invention, the phase control device for adjusting the resolution of the image pickup device for capturing an image stores the target value of the mark provided on the subject in advance and the characteristics relating to the image pickup device, and the image pickup device detects the object. Since the detected value of the mark is compared with the target value stored in advance, the distance between the image sensor and the mark of the subject is automatically adjusted so that the detected value and the target value are equal. , Especially 2000
Using a high-precision line camera that exceeds pixels, the position of the line camera can be automatically moved and adjusted to the target resolution. Moreover, since the control system can be simplified, the cost can be reduced.

The target resolution x, mark width g,
From the resolution d, the image capturing time Tb of the mark captured by the image sensor, and the capturing time Tc of the non-mark image, Δx = {(T
c / Tb) +1} (g / d) when the actual resolution Δx is larger than the target resolution x, the image sensor is brought closer to the subject, and when it is smaller than the target resolution x, By controlling the image pickup device so as to move away from the subject, it becomes easy to use an operational amplifier or the like as a phase control device to implement hardware, and thus a simple and high-speed device can be manufactured.

Further, the driving frequency f, or the resolution d, the horizontal period Ta, the mark width g, and the mark image capturing time T.
From b, Δg = Tb · f or Δg = Tb (d / Ta)
Mark width corresponding to the target resolution calculated by
By controlling g to be the mark width g, the phase controller can have versatility because the input value is a digital value.

Alternatively, when the mark width Δg corresponding to the preset target resolution is larger than the mark width g, the image pickup element is moved away from the subject, and when the mark width Δg is smaller than the mark width g, the image pickup element is set to the subject. By controlling the distance between the image pickup device and the subject so as to approach the image pickup device, the phase control device can process at a higher speed than the image processing device can take in, and the cost can be reduced because the calculation means can be omitted.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for automatically adjusting the resolution of an image pickup device according to the present invention will be described below with reference to FIGS.
First, FIG. 1 shows automatic adjustment of resolution by a line camera as an example to which the present invention is applied. (A) is a plan view showing an example of a subject of a glass substrate for adjustment, (b) is a line camera It is a schematic side view which shows an uptake. In FIG. 1B, Ca is a line camera as an image sensor, L is its lens, and G is an adjusting glass substrate. As shown in FIG. , A certain width colored in black by printing (g
A subject (test pattern) TP having a marking area MA as a mark (mm) is formed.

The line camera Ca has a high precision of more than 2000 pixels by a one-dimensional CCD, is equipped with a known automatic focus adjustment type lens L, and images an object TP along the width direction of the marking area MA. Sequential scanning (Fig. 1
(Refer to the arrow AA 'line in (a)), and then move to the next line and similarly scan the image sequentially along the width direction of the marking area MA of the subject TP. Here, it is a condition that the subject TP has an accuracy of about 1/10 of the target resolution. In addition, the line camera Ca
The angle is adjusted in advance with respect to the subject TP.

FIG. 2 shows the video signal VD of the line camera Ca.
And the horizontal synchronizing signal HD. That is, in the horizontal synchronizing signal HD, Ta represents a horizontal cycle (cycle for one line). In the video signal VD,
Tb represents the image capturing time of the marking area MA, and Tc represents the interval (imaging time of the non-marking area image). Therefore, there is a relation of Ta = Tb + Tc.

The focus itself of the line camera Ca is automatically controlled by an automatic focusing device F (see FIG. 4) described later. FIG. 3 shows an example of the output waveform of the line camera Ca. (A) shows the output waveform in the out-of-focus state, and (B) shows the output waveform in the focused state. That is, in the automatic focusing device F, the adjustment position where the wave height of the differential signal obtained by differentiating the video signal at the edge portion of the marking area MA is the highest is in focus (see FIG. 3B).

Next, FIG. 4 is a block diagram showing a structural example of an image pickup apparatus used in the method for automatically adjusting the resolution of an image pickup element according to the present invention. This image pickup apparatus includes a line camera Ca, an automatic focusing device F, and a lens drive motor. It is composed of M1, a phase control device S, and a camera moving motor M2. Automatic focusing device F
Is of a known structure, and the lens L is driven by the lens drive motor M1 based on the video signal VD from the line camera Ca to automatically adjust the focus.

Then, the phase control device S moves the line camera Ca in the vertical direction of FIG. 1 (b) by the camera moving motor M2 based on the video signal VD and the horizontal synchronizing signal HD from the line camera Ca to change the phase. Is to control. That is, the phase control device S uses the marking area M
Based on the duty ratio of the image capturing time Tb of A and the capturing time Tc of the non-marking area image of the subject TP,
The distance to the marking area MA (subject) is automatically set. Below, 1st Example of control by this phase control apparatus S, 2nd Example, and 3rd Example are demonstrated in order.

<First Embodiment> The following data is registered in advance. i) Target resolution of the line camera Ca x ii) Marking area width g iii) Resolution of the line camera Ca d The image capturing time Tb of the marking area MA and the capturing time Tc of the non-marking area image are measured from the video signal VD.

The following relational expression holds between the above elements. (G / x): {d− (g / x)} = Tb: Tc Therefore, the actual resolution Δx is Δx = {(Tc / Tb) +1} (g / d). Therefore, when the value of the actual resolution Δx based on the above equation is larger than the target resolution x, the magnification is small, and therefore the line camera Ca is lowered in FIG. 1B (close to the adjustment glass substrate G). ) As described above, and when the value of the actual resolution Δx is smaller than the target resolution x, the magnification is large, so in FIG. 1B, the line camera Ca is raised ( The camera moving motor M2 may be controlled so as to move away from the adjustment glass substrate G).

Since the above control is calculated only by the duty ratio between the image pickup time Tb of the marking area MA and the image pickup time Tc of the non-marking area image of the subject TP, an operational amplifier or the like is used as the phase control device S. Then, it becomes easy to implement hardware, and a simple and high-speed device can be made.

That is, FIG. 5 shows an example of the configuration of the phase control device S using an operational amplifier, in which 51 and 52 are voltage converters.
53 is a divider, 54 is a reference voltage setting unit, and 55 is a comparator. First, the image capturing time Tb of the marking area MA
And the shooting time Tc of the non-marking area image of the subject TP
Are respectively converted by the voltage converters 51 and 52 to obtain the voltage converted voltage values VTb and VTc, respectively. Then, the voltage-converted voltage values VTb and VTc are calculated by the divider 53 to obtain a calculated value VCmp. This calculated value VCmp represents the duty ratio, that is,
It is obtained from VCmp = (VTc / VTb). Further, the calculated value VCmp is compared with a set value VSet according to a parameter preset by the reference voltage setting unit 54 by the comparator 55, and the required motor drive voltage VO to the target set value VSet is obtained.
When ut is obtained, this motor drive voltage VOut is output to the camera movement motor M2.

As described above, the phase control and the autofocus control are simultaneously performed, and the line camera Ca has a target resolution x.
It becomes possible to adjust to automatically.

<Second Embodiment> The driving frequency f of the line camera Ca is input. Alternatively, the horizontal cycle Ta may be read from the horizontal synchronization signal HD. The image capturing time Tb of the marking area MA is measured from the video signal VD. The following relational expressions hold between the above elements. Δg = Tb · f or Δg = Tb (d / Ta) The target mark width Δ is the width g of the marking area MA.
The camera moving motor M2 is controlled so as to obtain g.

In this method, since the input value is a digital value, it is possible to have versatility.

<Third Embodiment> The image pickup time Tb of the marking area MA read from the video signal VD and the driving frequency f of the line camera Ca (or the horizontal cycle Ta read from the horizontal synchronizing signal HD) are input to the camera. The movement motor M2 is controlled. In this case, the target mark width △
When g is larger than the width g of the marking area MA,
In (b), the camera movement motor M2 is set so as to raise the line camera Ca (away from the adjustment glass substrate G).
When the target mark width Δg is smaller than the width g of the marking area MA, the line camera Ca is lowered (moved closer to the adjustment glass substrate G) in FIG. 1B. Control the motor M2.

This method does not require complicated knowledge of image processing and can be processed at a higher speed than when it is loaded into the image processing apparatus. Moreover, since the calculation means can be omitted, the cost can be reduced.

As in each of the embodiments described above, the present invention is a combination of the autofocus device F and the phase control device S,
By performing the automatic resolution adjustment of the line camera Ca, anyone can easily adjust the line camera Ca, and it is not necessary to change the complicated parameters of the image processing, and the adjustment and the work change can be performed inline at any time. Particularly, in the present invention, the target value of the marking area MA of the subject TP and the characteristic relating to the line camera Ca are stored in advance by the phase control device S, and the value in which the line camera Ca detects the marking area MA of the subject TP is stored in advance. And the marking area MA between the line camera Ca and the subject TP so that the detected value becomes equal to the target value.
Since the distance between and is automatically adjusted, the position of the line camera Ca can be automatically moved to the target resolution and adjusted by using the high-precision line camera Ca with more than 2000 pixels.

In the above embodiments, the high-precision line camera having a one-dimensional CCD with more than 2000 pixels is used as the image pickup device, but the present invention is not limited to this. Further, it is needless to say that the structures of the automatic focusing device and the phase control device are arbitrary, and in addition, the specific detailed structure including the actuator can be appropriately changed.

[0030]

As described above, according to the method for automatically adjusting the resolution of an image pickup device according to the present invention, the phase control device for adjusting the resolution of the image pickup device sets the target value of the mark previously provided on the object and the image pickup. The characteristics related to the device are stored, the value detected by the image sensor for the mark of the subject is compared with the target value stored in advance, and the mark of the image sensor and the subject is adjusted so that the detected value becomes equal to the target value. Since the distance between and is automatically adjusted, it is possible to automatically move and adjust the position of the line camera to a target resolution by using a high-precision line camera having more than 2000 pixels. Moreover, the control system can be simplified and the cost can be reduced.

As described in claim 2, Δx =
When the actual resolution Δx calculated by {(Tc / Tb) +1} (g / d) is larger than the target resolution x,
Bring the image sensor close to the subject and set the target resolution x
When it is smaller, if the image pickup element is controlled so as to move away from the subject, it becomes easy to use an operational amplifier or the like as a phase control device to implement hardware, so that a simple and high-speed device can be manufactured.

Further, as described in claim 3, the mark width g
Is controlled so that the mark width Δg corresponds to the target resolution calculated by Δg = Tb · f or Δg = Tb (d / Ta), the input value becomes a digital value as a phase control device. Therefore, versatility can be provided.

Alternatively, as described in claim 4, when the mark width Δg corresponding to the preset target resolution is larger than the mark width g, the image pickup device is moved away from the object and the mark width g is larger than the mark width g. When it is small, if you control the image sensor so that it comes close to the subject, as a phase control device,
Since the processing can be performed at a higher speed than that when the image processing apparatus is loaded, and the calculation means can be omitted, cost reduction can be achieved.

[Brief description of drawings]

1A and 1B show automatic adjustment of resolution by a line camera as an example to which the present invention is applied, in which FIG. 1A is a plan view showing an example of a subject on a glass substrate for adjustment, and FIG. It is a schematic side view which shows.

FIG. 2 is a diagram exemplifying a video signal and a horizontal synchronizing signal of a line camera.

FIG. 3 shows an example of an output waveform of a line camera,
(A) is an output waveform diagram in a defocused state, and (B) is an output waveform diagram in a focused state.

FIG. 4 is a block diagram showing a configuration example of an image pickup apparatus used in the method for automatically adjusting the resolution of an image pickup element according to the present invention.

5 is a circuit diagram showing a configuration example of the phase control device of FIG.

[Explanation of symbols]

 Ca image sensor L lens G adjustment glass substrate TP subject MA mark F autofocus device M1 lens drive motor S phase control device M2 camera movement motor VD video signal HD horizontal sync signal Ta horizontal period Tb mark image recording time Tc non-mark image Image capturing time 51,52 Voltage converter 53 Divider 54 Reference voltage setting unit 55 Comparator

Claims (4)

[Claims] 1. An image pickup device comprising an image pickup device for capturing an image and a phase control device for adjusting the resolution of the image pickup device, wherein the phase control device sets a target value of a mark previously provided on a subject. The characteristic relating to the image pickup device is stored, the value obtained by detecting the mark provided on the subject by the image pickup device is compared with the target value stored in advance, and the detected value and the target value are compared. A method for automatically adjusting the resolution of an image pickup device, wherein the distance between the image pickup device and the mark provided on the subject is automatically adjusted so that 2. The phase control device, wherein a target resolution x of the image sensor, a width g of the mark, a resolution d of the image sensor, an image capturing time Tb of the mark captured by the image sensor, The actual resolution Δx is calculated from the shooting time Tc of the unmarked image based on the following equation Δx = {(Tc / Tb) +1} (g / d), and the value of the actual resolution Δx is When the resolution x is higher than the target resolution x, the image sensor is brought closer to the subject, and when the value of the actual resolution Δx is smaller than the target resolution x, the image sensor is moved away from the subject. The method for automatically adjusting the resolution of an image pickup device according to claim 1, wherein 3. In the phase control device, a target resolution based on a drive frequency f of the image sensor, a resolution d and a horizontal period Ta of the image sensor, a width g of the mark, and an image capturing time Tb of the mark. The mark width Δg corresponding to is calculated based on the following formula Δg = Tb · f or Δg = Tb (d / Ta) so that the width g of the mark becomes the target mark width Δg. The method for automatically adjusting the resolution of an image pickup device according to claim 1, wherein the distance between the image pickup device and the subject is controlled. 4. In the phase control device, a mark width Δg corresponding to a target resolution is set in advance, and when the target mark width Δg is larger than the mark width g, the image pickup device Away from the subject, and the target mark width Δg is the mark width g.
The method for automatically adjusting the resolution of an image pickup device according to claim 1, wherein the image pickup device is controlled to approach the subject when the image pickup device is smaller than the image pickup device.