JPH07154667A - Method for adjustment of flange back of video camera using inner focus lens - Google Patents

Abstract

PURPOSE:To reduce the adjustment time by obtaining a telescopic end and a wide end based on the peak of an actual zoom tracking curve. CONSTITUTION:At first the peak of a zoom tracking curve is detected, and a variator 3 and a focus lens 5 are placed to the peak of the zoom tracking curve. Then the focus lens 5 is moved toward the far position by a specified amount T while unchanging the position of the variator 3. Then the variator 3 is used to search a focal position and the position of the variator 3 when focused is set as the telescopic end. Then the focus lens 5 is moved by a specified amount U. While the focus lens 5 is unchanged, the variator 3 is used to search a focused position and the position of the variator 3 when focused is set as a wide end. The peak of the zoom tracking curve is detected actually at first and the telescopic end and the wide end are decided based on the peak. Thus, no adjustment loop is required at adjustment of flange back and then the adjustment time is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a video camera using an inner focus lens, and a flange of the video camera using the inner focus lens for adjusting an error between a zoom tracking curve obtained in advance and an actual zoom tracking curve. Back adjustment method.

[0002]

2. Description of the Related Art In a video camera equipped with an inner focus lens, the focus lens is made to follow the movement of the variator so that the focus state can be maintained while the variator is moved for zooming. Such control is called zoom tracking control. The relationship between the position of the variator and the position of the focus lens which is the in-focus position is shown by a zoom tracking curve.

FIG. 7 is an example of a zoom tracking curve. In FIG. 7, the horizontal axis indicates the position of the variator,
The vertical axis represents the amount of extension of the focus lens. In addition, T
Reference numerals 1, T2, and T3 are zoom traversing curves when the subject is 1 m, 2 m, and infinity, respectively. If the focus lens is moved along such a zoom tracking curve when the variator is moved, it will be kept in focus.

However, the lens mounting position of the CCD image pickup device varies during manufacturing. Further, the zoom tracking curve obtained in advance differs from the actual zoom tracking curve due to variations in manufacturing the lens. Therefore, it is necessary to make an adjustment so that the image forming position of the lens system and the light receiving surface of the CCD image sensor actually coincide with each other.
Such adjustment is called flange back adjustment.

FIG. 8 is a flow chart showing an example of a conventional flange back adjustment method, and FIG. 9 is an explanatory view thereof. As shown in FIG. 7, the tracking curve is TE
It becomes steepest near the LE end side, and from the WIDE end to T
The apex exists at a position of about ⅔ until the end of the ELE.
At the apex, there is almost no slope of the zoom tracking curve. Therefore, near the apex, even if the variator is moved, the focus is hardly affected. On the contrary,
At the TELE end, the error in the position of the variator has a great influence on the focus. This means that from the adjustment side, it is easy to determine the position of the focus lens near the apex, and it is easy to determine the position of the variator at the TELE end side. The conventional flange back adjustment method shown in FIG. 8 utilizes this for adjustment.

First, the variator is moved to the position E1 which is the apex at the design value. Due to the mounting error of the CCD image pickup element, the position of the apex E1 at this design value has a deviation from the position of the apex of the actual zoom tracking curve (step ST51).

After the variator is set at the apex E1 of the design value, the position of the variator is left as it is, and the focus lens is moved to search for a focus position. When the focus lens is moved to the position of E2, it comes on the actual zoom tracking curve, so that it is in focus. When the subject is in focus, the position of the focus lens at that time is stored. (Step ST52).

Then, focuss from the top to TE
Move by T, which is the set value for the amount of movement to the LE end, then E3
(Step ST53).

Then, the focus lens is left as it is, and the position in focus is searched for while moving the variator. When the variator is moved to the position of E4, it comes on the zoom tracking curve and is in focus. When the position E4 in focus is searched by the variator, the position of the variator at this time is stored as the TELE end. The TELE edge detected in this way is deviated from the actual one because it is based on the apex of the design value (step ST54).

When the position of the TELE end is stored, the variator is moved by the specified amount S which is the set value of the moving amount of the variator from the TELE end to the apex, and is brought to the position of E5 (step ST55).

Then, the focus lens is moved to focus, and the position E6 of the focus lens when the focus is achieved is stored (step ST56).

As a result, the vertex of the zoom tracking curve is detected, but this vertex has an error from the actual vertex. It is determined whether the previously stored apex and the apex obtained this time are within a predetermined value (step ST57).

If the previously stored vertex and the vertex obtained this time are not within the predetermined values, the process returns to step ST53 and the same process is repeated using the vertex of this time. By repeating such processing, the previously stored vertex and the vertex obtained this time are within the predetermined value.

The fact that the previously stored apex and the apex obtained this time are within the predetermined value means that the apex is close to the actual apex. When this difference is within a predetermined value, the focus lens is moved by a prescribed amount U from the apex of the focus lens obtained in the previous steps to the position E8. The prescribed amount U is the WI of the focus lens
Corresponds to the amount of movement from the DE end to the vertex (step ST
58).

After the focus lens is moved by the specified amount, the variator searches for the in-focus position, and the in-focus position E9 is set at the WIDE end (step ST5).
9).

[0016]

In the above-mentioned conventional flange back adjustment method, the position of the TELE end is first determined with reference to the apex of the design value of the zoom tracking curve, so that the actual zoom tracking curve Apex and TEL
Adjustment loop ST53 to repeatedly obtain the E end
ST57 occurs. Therefore, there is a problem that the adjustment time becomes long.

Therefore, an object of the present invention is to provide a tracking adjustment method which can shorten the adjustment time.

[0018]

SUMMARY OF THE INVENTION The present invention provides a method for adjusting a flange back of a video camera using an inner focus lens for adjusting an error between a zoom tracking curve obtained in advance and an actual zoom tracking curve. Flange back adjustment method for a video camera using an inner focus lens, which comprises the steps of detecting the positions of the vertices on the tracking curve and the steps of determining the positions of both ends of the variator based on the vertices on the actual zoom tracking curve. Is.

[0019]

Since the apex on the actual zoom tracking curve is detected and the TELE end and the WIDE end are obtained with the apex on the actual zoom tracking curve as a reference, the adjustment loop is eliminated and the adjustment time can be shortened.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The present invention is applied to the flange back adjustment in a video camera having an inner focus lens as described above. In the present invention, when the flange back adjustment is performed, first, the apex of the actual zoom tracking curve is obtained. Therefore, the adjustment time can be significantly shortened.

As shown in FIG. 1, the inner focus lens 1 is provided with a fixed lens 2 at the front, followed by a variator 3 for zooming, a fixed lens 4 and a focus lens 5. An iris 6 is provided between the variator 3 and the fixed lens 4.

A CCD image pickup device 7 is arranged at a predetermined distance from the inner focus lens 1. The output of the CCD image pickup device 7 is supplied to the video signal processing circuit 8.
The video signal processing circuit 8 forms a video signal from the output signal of the CCD image pickup device 7. Video signal processing circuit 8
From which the component of the luminance signal Y is output, and the high-pass component of this luminance signal Y is extracted by the high-pass filter 9. The output of the high pass filter 9 is supplied to the detection circuit 10. From the output of the detection circuit 10, the high frequency component level of the luminance signal is detected. A contrast signal S1 is obtained from the output of the detection circuit 10. The contrast signal S1 is supplied to the system controller 11 and used as a signal for evaluating the in-focus state.

The positions of the variator 3 and the focus lens 5 can be moved by lens drive motors 12 and 13. Further, the position of the variator 3 is detected by the sensor 14, and the output of the sensor 14 is output by the system controller 1.
1 is supplied. When zooming is performed by moving the variator 3, tracking control is performed such that the focus lens 5 is moved so as to follow the movement of the variator 3 so that focusing can be continued. A table for realizing this tracking control is prepared in the system controller 11, and the focus lens 5 is moved following the movement of the variator 3.

The previously obtained zoom tracking curve and the actual zoom tracking curve are the CCD image pickup element 7
It depends on variations in the mounting position during manufacturing. Therefore, flange back adjustment is necessary.

FIG. 2 is a flow chart showing a flange back adjusting method to which the present invention is applied, and FIG. 3 is an explanatory view thereof. It is assumed that the actual zoom tracking curve is as shown in FIG. In FIG. 3, the horizontal axis indicates the position of the variator 3, the right side is the TELE side,
The left side is the WIDE side. The vertical axis indicates the position of the focus lens 5, the upper side is the near side, and the lower side is the far side. When the variator 3 and the focus lens 5 are on this zoom tracking curve, focusing is achieved.

As shown in FIG. 2, in the flange back adjusting method to which the present invention is applied, first, the apex of the zoom tracking curve is detected, and the variator 3 and the focus lens 5 are positioned at the apex of the zoom tracking curve. (Step ST1). That is, first, the variator 3 and the focus lens 5 are brought to the position A1 in FIG. How to detect the position of the apex of the zoom tracking curve will be described later.

Next, the position of the variator 3 remains unchanged,
The focus lens 5 is moved to the far side by the specified amount T (step ST2). That is, the variator 3 and the focus lens 5 are brought to the position A2 in FIG.

Then, the variator 3 is set at the position in focus.
Search with. From the position of A2 in FIG. 3, the position of the focus lens 5 is unchanged and the variator 3 is TEL.
When it is moved to the E side, it comes to the zoom tracking curve at the point A3 and comes into focus. In this way, the position of the variator 3 when in focus is set as the TELE end (step ST3).

Next, the focus lens 5 is moved by the specified amount U. That is, the variator 3 and the focus lens 5 are brought to the position A4 in FIG. 3 (step ST4).

When the focus lens 5 is moved by the specified amount U, the position of the focus lens 5 remains unchanged and the variator 3 searches for a focus position. Variator 3
When is moved from A4 in FIG. 3 to the WIDE side, the zoom tracking curve comes at the position of A5 and the focus is achieved. In this way, the position of the variator 3 when focused is set as the WIDE end (step ST
5).

As described above, in the flange-back adjusting method to which the present invention is applied, first, the apex of the actual zoom tracking curve is detected, and the TEL is set on the basis of this apex.
The E end and the WIDE end are determined. Therefore, the adjustment loop is eliminated during the flange back adjustment, and the adjustment time can be shortened. The apex of the actual zoom tracking curve can be detected as follows.

FIG. 4 is an explanatory diagram of an example of a method for detecting the apex of the zoom tracking curve. As shown in FIG. 4, first, as an initial position, the variator 3 is slightly adjusted to the WIDE side and the focus lens 5 is adjusted to the slightly near side from the position where the apex of the zoom tracking curve will be located. That is, as the initial position, the variator 3 and the focus lens 5 are set at the point B in FIG. 4A.
Put in 1.

Next, while the focus lens 5 is fixed, the contrast signal S1 is observed while moving the variator 3 from the initial position to the TELE side. The contrast signal S1 is obtained from the output of the detection circuit 10 in FIG. 1, and the contrast signal S1 has a maximum value at the time of focusing and has a small value as the focus is blurred.

Therefore, when the variator 3 is searched, the contrast signal S1 changes as shown in FIG. 4B, and the position of the variator 3 shown in FIG. The shift is minimized and the contrast signal S1 is maximized.

Position B where the contrast signal S1 is maximum
2 with the variator 3 fixed and the focus lens 5 fa
Search in the r direction. Then, the focus position is obtained. As a result, the position B3 of the apex of the zoom tracking curve shown in FIG. 4A is obtained.

Here, an example in which the variator is searched in the direction from the WIDE end to the TELE end has been shown.
The LE end side may be changed to the WIDE end side.

FIG. 5 is an explanatory view of another example of the method for detecting the apex of the zoom tracking curve.

As shown in FIG. 5, first, as an initial position, the variator 3 is slightly adjusted to the WIDE side and the focus lens 5 is adjusted to the slightly near side from the position where the apex of the zoom tracking curve will be located. That is, as the initial position, the variator 3 and the focus lens 5 are placed at the point C1 in FIG. 5A.

Next, with the position of the variator 3 unchanged,
Search the focus lens 5 and focus. When the focus lens 5 is moved to the far side, it comes on the tracking curve at the point C2 in FIG. 5, so that the contrast signal S1 is maximized and focused as shown in FIG. 5B.

Next, with the focus lens 5 fixed, the variator 3 is moved in the TELE direction to search for a focus position. When the variator 3 is moved in the TELE direction, the variator 3 comes back on the zoom tracking curve at the point C3 in FIG. 5A, so that the contrast signal S1 becomes maximum at the position of the point C3 and the focus is achieved.

While moving the variator 3 in this way, the contrast signal S1 is observed. When the variator 3 reaches the position C4 which is the apex of the zoom tracking curve, the focus shift becomes maximum as shown in FIG. 5A. Therefore, the contrast signal S1 is minimized as shown in FIG. 5B.

The variator 3 is moved to the position C4 where the contrast signal becomes the minimum, and from there, the focus lens 5 is searched toward the near side to find the point of focus. Focus is obtained by moving the focus lens 5 to the point C5, and the vertex of the zoom tracking curve is obtained from this position.

In this case also, the variator 3 is set to TEL.
You may make it search from the E side to the WIDE side.

FIG. 6 is an explanatory diagram of still another example of the method for detecting the apex of the zoom tracking curve. First, as the initial position, the variator 3 is set to a slightly WID from the position where the apex of the zoom tracking curve will be located.
Align the focus lens 5 on the E side to the near side slightly. That is, as the initial position, the variator 3 and the focus lens 5 are placed at the point D1 in FIG. Then, the focus lens is used to search for the in-focus position D2.

Next, while moving the variator 3 to the TELE side, the focus lens 5 is moved so as to be always in focus by the autofocus control. During this time, the position of the focus lens 5 is observed. When the variator 3 is moved from the point D2 to the TELE side, the focus lens 5 moves according to the zoom tracking curve, the focus lens moves to the near side up to the point C4, and then the focus lens moves to the far side. Position D3 where the position of the focus lens is closest to the near side
And the vertex of the zoom tracking curve is obtained from this position.

In this case as well, the variator 3 is set to TELE.
An algorithm for searching from the WIDE side to the WIDE side may be used.

[0047]

According to the present invention, the apex on the actual zoom tracking curve is detected, and the TELE end and the WID are set with reference to the apex on the actual zoom tracking curve.
Seeking the E end. Therefore, the adjustment loop is eliminated during the flange back adjustment, and the adjustment time can be shortened.

[Brief description of drawings]

FIG. 1 is a block diagram of an example of a video camera including an inner focus lens to which the present invention can be applied.

FIG. 2 is a flow chart used to explain an embodiment of the present invention.

FIG. 3 is a schematic diagram used to describe an embodiment of the present invention.

FIG. 4 is a schematic diagram used to describe an example of a method for detecting a vertex of a zoom tracking curve.

FIG. 5 is a schematic diagram used to describe another example of the method for detecting the apex of a zoom tracking curve.

FIG. 6 is a schematic diagram used for explaining still another example of the method for detecting the apex of the zoom tracking curve.

FIG. 7 is a schematic diagram of an example of a zoom tracking curve.

FIG. 8 is a flowchart of an example of a conventional flange back adjustment method.

FIG. 9 is a schematic diagram used to describe an example of a conventional flange back adjustment method.

[Explanation of symbols]

 1 Inner focus lens 3 Variator 5 Focus lens

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Claims (1)

[Claims] 1. A method of adjusting a flange back of a video camera using an inner focus lens for adjusting an error between a zoom tracking curve obtained in advance and an actual zoom tracking curve, and a position which is a peak on the actual zoom tracking curve. And a step of determining the positions of both ends of the variator on the basis of the vertices on the actual zoom tracking curve, and a flange-back adjusting method for a video camera using an inner focus lens.