JPS602827B2 - television camera equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a television camera device with a focus adjustment mechanism.

In a television camera device, when the total optical point is shifted, it is necessary to easily adjust the focus, and the present invention is effective when applied to such a case.

The details of this invention will be explained below based on the drawings.

FIG. 1 shows an embodiment of the invention.

In the figure, 1 is a television camera consisting of a television camera body 1-1, an optical focus adjustment mechanism 1-2 for adjusting the focal position, and other necessary equipment, and 2 is a television camera that distributes the output of the television camera. A distributor, 4, is a predetermined partial extraction circuit, 5, which extracts only a part of the captured image as required.
6 is a predetermined frequency component extraction circuit that allows only signal components of a certain frequency to pass; 6 is a circuit for extracting the predetermined frequency component from the optical circuit; This is a control signal generation circuit that generates a control signal to control the point adjustment mechanism 1-2.

Further, 3 is an output terminal for sending the output of the television camera 1 to an external device, and 10 is an object to be photographed.
In the television camera 1, the optical V-point adjustment mechanism 1-2
By adjusting the , you can focus the heat on objects at various distances.

However, when the target object is located at a certain distance Lo from the television camera 1, when the trout point adjustment mechanism 1-2 is adjusted, the signal components included in the output signal of the television camera 1 change as shown in Fig. 2. .

In other words, the high frequency component is Lo as shown in curve A.
The peak value is reached when the focal position is aligned with , and decreases when the Kurama point is aligned ahead or behind that point. Moreover, as shown in curve B, the frequency component of Nakagusuku shows a rather higher level when the focal point position is slightly before or after Lo.

Furthermore, as shown in curve C, the low frequency component takes a peak value at a position considerably deviated from the focal position.

These phenomena are explained as follows.

In other words, if the focus position matches the target subject, the ring
is clearly imaged, so the output signal of the television camera 1 changes sharply in this part, but as the focal position shifts, the signal changes in this circular part become more gradual depending on the degree of focal position shift. become.

Therefore, the frequency components included in the output signal of the television camera device 1 shift from higher to lower frequency components in accordance with the shift in the focal position, resulting in the mirror direction shown in FIG. The present invention has focused on this point and provides a television camera device that allows easy optical focus adjustment when the focal position has shifted.

FIG. 3 shows an example of a device for detecting the adjustment signal of the present invention.

Components with the same reference numerals as in FIG. 1 indicate components with the same functions.

5-1-1 is a first filter that extracts Takagi frequency components, 5-1-2 is a second filter that extracts Nakagusuku frequency components, and 5-1-3 is a filter that extracts low frequency components. the third filter, 5-2-1, 5-2-2, 5-2-
Reference numerals 3 denote first, second, and third detection circuits that envelope-detect the output signals of the first, second, and third filters, respectively.

The predetermined frequency component extraction circuit 5 extracts each frequency component included in the output signal of the television camera, and applies these signals to the control signal generation circuit 6 to perform the following control. For example, if the focal position is at Lo-L in Figure 2 and the optical focus adjustment mechanism is adjusted in the direction of increasing the focal position, the Takagi frequency component is curve A, so the level is small and there is little change. , the Nakagusuku component is curve B, so the level is relatively high and tends to increase.

Furthermore, since the low-quality component is on curve C, the level is relatively high but tends to decrease. By continuing to make adjustments to increase the total point position based on the above data, it is possible to reach a mountain where the focal position matches the target object.

Specifically, when comparing changes in the Takagi frequency component that occur in response to changes in the focal position, changes in the Nakagusuku frequency component, and changes in the low frequency component, it is found that in the vicinity of Lo-L, the high frequency component is almost overshadowed by noise. On the other hand, the Nakagusuku frequency component has begun to climb the peak of the hump characteristic, and the low frequency component has begun to descend toward the valley of the hump characteristic.

When the focal position is further brought closer to Lo, the Nakagusuku frequency component begins to go down to the valley after passing through the peak of the hump characteristic, and at the same time, the Takagi frequency component begins to rise.

Note that the high frequency component does not have a hump characteristic, so even if the middle frequency component and the low frequency component are near the center of the broad valley of the hump characteristic, they can be detected sharply at the in-focus position Lo. Serve. The above-mentioned change characteristics are uniquely determined by how the frequency range of the video signal to be extracted is divided by checking each signal by comparing relative values instead of absolute values.

Therefore, the current control method is to look at the relationship between changes in high frequency components and other components. The position of the focus is determined and the focus adjustment mechanism is adjusted to a predetermined focus position according to the result.

It is a matter of course that the control in this case should be considered by configuring a well-known servo mechanism to improve control accuracy. Next, when the focal position rubs L+L' and the adjustment is made to increase the focal position, the characteristic curve in Figure 2 shows that the direction of adjustment is the opposite, so the adjustment is made to decrease the focal position. I understand that I have to change it to .

FIG. 4 shows an example of the control signal generation circuit 6 that implements the above-mentioned control.

The high frequency component A, middle frequency component B, and low frequency component C extracted by the predetermined frequency component extraction circuit 5 are each converted into a digital signal at a predetermined sampling time by an A/D converter 6-1. The signal is input to one of the comparators 6-4 via the buffer memory IJ6-2, and is further input to the other comparator 6-4 via the buffer memory 6-3.
That is, in the comparator 6-4, the current sample value of each frequency component is input from the buffer memory 6-2, and the previous sample value of each frequency component is input from the buffer memory 6-3. For example, the current sample value for high frequency component A is compared with the previous sample value, and if it has increased, 11 is output, if it has decreased, -1 is output, and if it is constant, 0 is output as signal a. Increases and decreases in other frequency components are similarly detected, and the comparator 6-4 obtains outputs a, b, and c. By the way, in FIG. 2, when the focus position moves to the right, the comparator 6-
As shown in FIG. 5, the increase/decrease in each frequency component outputted from 4 can be identified into seven combinations corresponding to the waveform diagram of FIG. 2.

Therefore, by storing these combinations in advance in the discriminator 6-5, the comparator 6-4 obtained according to changes in the focal position
By identifying which combination the outputs of d correspond to, it is possible to generate a control signal d that increases (10) or decreases (1) the focal position. Note that if the direction of movement of the focal point position is opposite to that described above, a reverse control signal may be generated.
As described above, the output signal data of the first detector 5-2-1, the second detector 5-2-2, and the third detector 5-2-3 are control signals for performing the required control. to occur.

Further, although the above description has been made regarding the case where optical focus adjustment is performed, it is of course applicable to the case where focus adjustment is performed by electrical means.

Further, in the configuration shown in FIG. 1, it has been described that the optical focus is directly adjusted using an external signal, but the adjustment can be similarly easily performed even if it is performed manually according to a predetermined frequency extraction circuit output signal or the like.

As described above, according to the present invention, the Takagi frequency component and the lower frequency component of the video signal are detected, and the focus is adjusted using the control signal obtained according to the relative change in these detection signals. This has the advantage of being able to focus on a wide range of focus deviations through control using only video signals, and simplifying the configuration and control.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory diagram illustrating an embodiment of the present invention, FIG. 2 is a diagram illustrating changes in the output signal of a television camera device due to a shift in optical focus, and FIG. FIG. 2 is a configuration diagram showing an embodiment of a predetermined frequency component extraction circuit, which is one of the components of the present invention. Further, FIG. 4 is a block diagram showing an embodiment of a control signal generation circuit which is one of the constituent elements of the present invention, and FIG. 5 explains the operation of the circuit shown in FIG. 4 in correspondence with FIG. 2. It is a diagram.
In the figure, 1 is a television camera, 1-1 is a camera body, and 1-2 is an optical camera. Focus adjustment mechanism, 2 is a distributor, 3 is an output terminal, 4 is a predetermined portion detector, 5 is a predetermined frequency component extraction circuit, 6 is a control signal generation circuit, 1 is a subject, 5-1
-1, 5-1-2, 5-1-3 are the first and second, respectively.
Third filter, 5-2-1, 5-2-2, 5-2-3
are the first, second, and third detectors, respectively. Note that the same reference numerals in the figures indicate the same or corresponding parts. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. A television camera having a focus adjustment mechanism, a first detection circuit that detects high frequency components included in the television camera output signal, and a second detection circuit that detects frequency components lower than the high frequency components. and the focus adjustment signal that controls the focus position in a predetermined direction according to relative changes in the respective outputs of the first detection circuit and the second detection circuit that change in accordance with changes in the focus position. A television camera device equipped with a control signal generation circuit for sending to a mechanism.