JPS62269496A - Flange back detecting device - Google Patents

Abstract

PURPOSE:To quantitatively detect the deviation of a flange back, by arranging a chart which is ranged to a marker, and both sides of the marker, and is constituted of a stripe pattern having a color possible to be distinguished from the marker, obliquely to an image pickup plane. CONSTITUTION:A chart 1 is placed so that the center marker 4 of the chart 1 is positioned at the position of a prescribed distance L1 at the front of a video camera, and the chart 1 is arranged so as to have the inclination of angle theta to the parallel state of the video camera as shown in double dotted chain line. In case of focusing on the marker 4, a flange back F is decided as proper. When it is necessary to adjust the flange back, a focusing position is generated in the stripe pattern ranging to the right and left sides of the marker, and the focusing position changes corresponding to the direction, and the quantity of the deviation of the flange back. In such way, by detecting the deviation(time difference) between the position of the marker 4, and the actual focusing position from the image pickup output signal of an image pickup element 3, the flange back F can be detected quantitatively.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention is applied to the kW construction of a video camera.
The present invention relates to a flange back detection device for detecting the distance between a photographic lens and an imaging surface, that is, flange back.

[Invention (already required)]

The present invention relates to a flange back detection device for detecting a predetermined optical positional relationship between a photographing lens and an image sensor of a video camera. A chart consisting of is arranged tilted with respect to a position parallel to the imaging surface, and in the imaging output signal of this chart, the time difference between the signal corresponding to the marker and the signal corresponding to the in-focus position in the stripe pattern is calculated. This is a flange back detection device that is capable of quantitatively detecting the deviation of Francisba ivy by detecting the deviation of the flange back.

[Conventional technology]

The photographing lens and image sensor of a video camera must be placed in a predetermined positional relationship in order to form an accurate image. This optical alignment is called flange back adjustment, and in the past, it was installed based on dimension settings, or by photographing a chart called the Siemens Star.
Adjustments were made through trial and error based on the degree of blur in the image reproduced on the monitor.

[Problem that the invention seeks to solve]

Conventionally, it has been difficult to quantitatively determine the amount of flange bank, and flange back adjustment has been forced through trial and error. Therefore, productivity was poor and automation of the adjustment process was difficult.

An object of the present invention is to provide a flange back detection device that can quantitatively detect the direction and amount of deviation of an image sensor from a set position, facilitate flange bank adjustment, and automate the adjustment process. The purpose is to provide.

[Means for solving problems]

This invention provides a photographic lens 2 and an image sensor 3 of a video camera.
In the flange back detection device for detecting a predetermined optical positional relationship with the marker 4 and the marker 40
A chart 1 consisting of striped patterns IA and IB of colors that are continuous on both sides and can be distinguished from the markers 4, and the markers 4 are aligned with optically set positions.
The stripe pattern IA on one side of the marker and the stripe pattern IB on the other side of the marker and the photographing lens 2
The image sensor 3 that photographs the chart 1 at different distances from the image sensor 3, and the time difference between the signal corresponding to the marker 1 in the output signal of the image sensor 3 and the signal corresponding to the in-focus position in the stripe pattern. Circuit I for detecting ΔT
This is a flange back detection device equipped with I, 12, 13°, 14, 15, 17.

[Effect]

If marker 4 on center 1 is in focus, flange back is appropriate. If the flange back' needs to be adjusted, a focused position will be created in the stripe pattern that continues on the left and right sides of the marker 4. This focused position changes depending on the direction and amount of the flange back shift.

Therefore, flange back can be detected quantitatively by detecting the shift (time difference) between the marker position and the actually focused position from the image pickup output signal of the image pickup element.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1 showing the optical configuration of this embodiment, 1 is a chart, 2 is a photographing lens, and 3 is an image pickup device such as a CCD. The photographic lens 2 and the image sensor 3 are incorporated into a video camera or a camera-integrated VTR.

The photographic lens 2 is mounted on a surface (in Fig. 1, the photographic lens 2 is
The distance F between the center of the image sensor 3 ) and the imaging surface of the image sensor 3 is the flange back. This flange back F is adjusted to the correct value. The chart 1 is placed so that the marker 4 at the center of the chart 1 is located a predetermined distance L1 in front of the video camera. In this case, the chart l is arranged at an angle θ with respect to the state parallel to the video camera shown by the two-dot chain line. The predetermined distance I, 1 is a distance at which the marker 4 at the center of the chart I is originally in focus, and if the marker 4 is in focus, the flange back F is appropriate. Further, when displaying the photographic output of the chart 1 on a monitor, the horizontal width of the screen 6 of the monitor and the width of the chart 1 are matched, as shown in FIG. The chart 1 displayed on the monitor screen 6 is an image in which only a specific portion is in focus.

As shown in FIG. 4A, the chart 1 has a pattern of rectangular stripes of a predetermined color. Char 1
A red (R) marker 4 is placed in the center of -1, and a green (G) S] live is located on both sides of it. (shaded area) stripes and green stripes are provided alternately. The widths of these stripes are made equal to each other.

Since Char 1-1 is arranged at an angle like Lj water, the Char 1-1 that is in focus depends on the distance at which Pin 1 matches.
The point II- changes. t longer than the predetermined pressure 1iiiIH,I? When the focus is achieved when the distance is 1.), the focused position is included in one side IA of Char 1.1, and when the pin 1 is focused at a distance shorter than the specified distance 1. The in-focus position is included within the other side IB of 11.

FIG. 3 shows the signal processing configuration of one embodiment of U7, and the imaging signal from the image sensor r3 is supplied to the camera output processing circuit 10. A signal Sr and a green imaging signal Sg are respectively taken out.

The imaging signal Sr is supplied to the peak detection circuit 11, and the imaging signal Sg is supplied to the peak detection circuit 13 via the bypass filter 12. These peak detection circuits 11 and 1
3. The peak values within one horizontal period Th of each of the imaging signals Sr and Sg are detected.

[Peak Detection Circuit] The output signals of 1 and 13 are supplied as sampling pulses to sample and hold circuits 14 and 15, respectively. →The non-pull pole circuits 14 and 15 are supplied with a sawtooth voltage (31;) with a horizontal circumference HH゛h from the input terminal 16.
The sampling outputs of are added in the adder circuit 17 in opposite phases. The output voltage from the adder circuit 17 is taken out to the output terminal 7-18. To this output voltage, ■ indicates the direction of the flange back 1) and the star.

In one embodiment of the present invention, as shown by ■ and 2 in FIG. 1, the distance +1 is shorter than the predetermined focus distance L1! The operation when the camera is in focus at -2 will be explained with reference to FIG.

- As an example, the other (i
When the pin I is aligned with the black stripe 5 in the jll IB, the green image pickup signal Sg is not shown in FIG. 4B. In other words, when the focus is off, the level of the imaging signal Sli is low and the waveform does not become a pulse signal, whereas when the focus is on, the illumination black stripe 5
Imaging information regarding green stripes adjacent to % S g
The level is high, and the waveform is like a pulse signal.

This imaging signal Sg is supplied to the bypass filter 2,
The bypass filter 12 generates an output signal shown in FIG. 4C that is proportional to the high frequency components contained in the image pickup signal 3g.

The red imaging signal Sr reaches its maximum level at the timing corresponding to the marker 4, as shown in FIG. The level of the imaging signal of the marker 4 changes depending on the focused position, but the peak position corresponds precisely to the marker 4.

The peak detection circuit 11 generates a 4) combining pulse shown in FIG. A sampling pulse shown in FIG. 4F is generated which coincides with the timing. These sampling pulses have a time difference of ΔT.

This time difference T corresponds to the amount and direction of the deviation of the in-focus distance L2 from the predetermined distance L1.

Horizontal period '1'11 not shown in Figure 4G from input terminal 16
Since the sawtooth wave voltage is non-pulled by the sampling pulses from the peak detection circuits 1 and 13, the voltage V is obtained at the output terminal 8, which corresponds to the amount and direction of the deviation mentioned above. It will be done. Although not shown, this differential voltage ΔV is displayed by an indicator. Flange pack F
The differential voltage is adjusted while watching the indicator so that V becomes zero. The adjustment is not limited to manual adjustment, and automatic adjustment may be performed so that the differential voltage V becomes zero.

Note that as the pattern of the chart 1, the pattern of the above-mentioned embodiment IM can be used as long as the center marker 4 and the stripes on the left and right sides of the marker 4 can be distinguished. For example, blue stripes may be used instead of green stripes. In addition, it is possible to adjust the tilting direction of the image sensor by capturing images of the charts at four positions on the top, bottom, left, and right of the monitor screen, and focusing each of these four charts in the same manner as described above. can.

〔Effect of the invention〕

According to the present invention, when adjusting the position of the image sensor to an optically appropriate relative position to the photographing lens, the direction and amount of the flange back shift can be quantitatively detected, which is different from the conventional method. There is no need to make trial-and-error adjustments, and
Automatic flange back adjustment is possible.

[Brief explanation of the drawing]

FIG. 1 is a route map showing the optical configuration of an embodiment of this invention, FIG. 2 is a route map showing a monitor screen of an embodiment of this invention, and FIG. 3 is an electrical route map of an embodiment of this invention. FIG. 4 is a block diagram showing the construction of the present invention, and FIG. 4 is a route map and a waveform diagram of each part used to explain an embodiment of the present invention. Explanation of main symbols in the drawings 1: chart, 2: photographing lens, 3: image sensor, 4: marker.

Claims (1)

[Scope of Claim] A flange back detection device for detecting a predetermined optical positional relationship between a photographing lens and an image sensor of a video camera, comprising a marker and a color that is continuous on both sides of the marker and is distinguishable from the marker. A chart consisting of a striped pattern and the above markers are matched to optically set positions,
an image sensor that photographs the chart in a state where distances between the stripe pattern on one side of the marker and the stripe pattern on the other side of the marker and the photographing lens are different from each other; A flange back detection device comprising: a circuit for detecting a time difference between a signal corresponding to the marker and a signal corresponding to an in-focus position in the stripe pattern.