JP2006229702A - Imaging apparatus and focus control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify the circuit configuration for realizing an autofocus function of an imaging apparatus composed with a camera instrument and a focus controller separated from each other, and reduce the cost of the apparatus. <P>SOLUTION: An object image is formed on an imaging device 21 by a focusing lens 11 of a lens unit 10. Based on a video signal outputted by photoelectric conversion in this imaging device 21, a composite video signal is generated by the video signal processing circuit 22 of the camera instrument 20. Moreover, a contour correction signal is generated by a contour correction generation circuit 25, and a focus evaluation value is detected from the contour correction signal by an evaluation value detection means 23. This detected focus evaluation value is transmitted to the focus controller 40, and the focusing lens 11 is controlled by a focus control means 42 on the basis of the focus evaluation value. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an imaging device capable of processing a subject image captured via a focus lens by a camera device and projecting it on a monitor device, and automatically controlling the focus lens by a focus control device, and a focus in the imaging device More particularly, the present invention relates to an imaging apparatus in which a camera device and a focus control apparatus are separately provided, and a focus control method in the imaging apparatus.

2. Description of the Related Art An imaging device that has a function of projecting a subject image captured by a focus lens on a monitor device and automatically controlling the focus lens is known.
In addition, in the imaging device, a camera device having a function of projecting a subject image captured via the lens device on a monitor device and a focus control device having a function of controlling a focus lens of the lens device are separated. Some have a structure.

FIG. 5 shows a functional configuration of a conventional imaging apparatus having such a configuration.
In the imaging apparatus 100 shown in the figure, in order to focus the focus lens 111 of the lens apparatus 110, the composite video signal transmitted from the camera apparatus 120 is received by the focus control apparatus 140 and extracted by the evaluation value detection unit 141. The focus lens 111 is controlled by the focus control unit 142 so that the frequency component of a certain frequency is detected and the signal component becomes the maximum value.

Here, the control in the focus control device 140 will be further described.
The composite video signal generated by the video signal processing circuit 122 of the camera device 120 is transmitted to the focus control device 140 and input to the trap filter 141-1 of the evaluation value detection unit 141. Here, after the color signal component is attenuated, the high-pass filter 141-2 extracts a frequency component above a certain level, and the peak detection circuit 141-3 is a focus evaluation value that is a peak value in one field or one frame. (Evaluation value) is obtained. Then, the focus control unit 142 adjusts the position of the focus lens 111 through the focus motor 112 so as to monitor the focus evaluation value so that the value becomes the maximum value, and performs a focusing operation by so-called hill-climbing autofocus. ing.

Since the focus evaluation value changes like a mountain-shaped characteristic curve having a vertex at the focal point with respect to the position of the focus lens 111, the focus control unit 142 always increases the evaluation value of the focus lens 111 by the focus motor 112. When the evaluation value decreases, the focus motor 112 is reversed, and the focus lens 111 is returned and stopped to a position where the evaluation value is recognized as the maximum (see, for example, Patent Document 1).
JP-A-7-288733

  However, since the focus control device in the conventional imaging device requires various circuits such as a trap filter and a high-pass filter in order to create a signal for calculating the focus evaluation value, the configuration is complicated and the cost is low. There was a problem that it took.

  Furthermore, when performing irreversible processing such as compression processing when transmitting a composite video signal, or when performing long distance transmission, the contour correction signal component extracted from the composite video signal may be reduced, There was a problem that the characteristics of the autofocus function deteriorated.

  The present invention has been made to solve the above-described problem, and in an imaging device in which a camera device and a focus control device are separately configured, a circuit configuration for realizing an autofocus function is simplified. An object of the present invention is to provide an image pickup apparatus and a focus control method that can reduce the cost of the entire focus control apparatus and the image pickup apparatus and that can prevent deterioration of the characteristics of the autofocus function.

  In order to achieve this object, an image pickup apparatus according to the present invention includes a camera device that generates and outputs a composite video signal based on a subject image captured via a lens device, and a focus control device that controls a focus lens of the lens device. Is an image pickup apparatus configured separately from each other, wherein the camera apparatus generates contour correction signal generation means for generating a contour correction signal based on the composite video signal, and an evaluation value for detecting the evaluation value based on the contour correction signal A detection unit; and a transmission unit that transmits the evaluation value to the focus control device. The focus control device includes a reception unit that receives the evaluation value; and a focus control unit that controls the focus lens based on the evaluation value. As a configuration.

When the imaging apparatus has such a configuration, a circuit for obtaining a focus evaluation value (evaluation value) is provided not in the focus control apparatus but in the camera apparatus in an imaging apparatus configured by separating the camera apparatus and the focus control apparatus. Therefore, the circuit configuration for realizing the focus control function can be simplified.
For example, when the evaluation value detection means is provided in the focus control device, it is necessary to provide means for extracting a component corresponding to the contour correction signal from the composite video signal. On the other hand, when the evaluation value detection means is provided in the camera device, a circuit block for generating a normal contour correction signal is originally mounted, so that a circuit for extracting a component corresponding to the contour correction signal is not necessary. . Therefore, by providing the evaluation value detection means in the camera device instead of the focus control device, the circuit configuration for realizing the focus control function can be simplified, the focus control device can be downsized, and the cost of the entire imaging device can be reduced. -It can be suppressed.
In addition, in the imaging apparatus of the present invention, it is not a composite video signal but a focus evaluation value, that is, data that is sent from the camera apparatus to the focus control apparatus. For this reason, the deterioration of the autofocus characteristic can be greatly reduced.

In the imaging apparatus of the present invention, the evaluation value detection unit converts the contour correction signal into an absolute value, and an integration circuit that detects the evaluation value by integrating the contour correction signal converted into the absolute value. It is set as the structure provided with.
If the imaging apparatus has such a configuration, the focus evaluation value can be detected based on the contour correction signal output from the contour correction generation circuit mounted on the camera device.

In the imaging apparatus of the present invention, the evaluation value detection means includes an analog-digital conversion means and / or a digital-analog conversion means between the integration circuit and the transmission means.
When the imaging apparatus has such a configuration, it can cope with a case where one of the integration circuit and the transmission circuit is an analog circuit and the other is a digital circuit.

In the imaging apparatus of the present invention, the integration circuit detects the evaluation value by integrating the contour correction signals for one field or one frame.
When the imaging apparatus has such a configuration, the camera apparatus can detect the focus evaluation value by integrating the contour correction signals for one field or one frame.

Further, the imaging apparatus of the present invention is configured to include a maximum value detection circuit that detects a maximum value in one field or one frame of the contour correction signal as an evaluation value, instead of the integration circuit.
When the imaging apparatus has such a configuration, the camera apparatus can detect the maximum value in one field or one frame of the contour correction signal as the focus evaluation value.

  Further, the focus control method of the present invention is a process for generating and outputting a composite video signal by a camera device based on a subject image captured via a lens device, and a focus control device provided separately from the camera device. A focus control method including a process for controlling a focus lens of a lens apparatus, wherein a camera apparatus generates a contour correction signal based on a composite video signal, and a camera apparatus evaluates based on the contour correction signal. Processing for detecting the value, processing for transmitting the evaluation value to the focus control device by the camera device, processing for receiving the evaluation value by the focus control device, and controlling the focus lens based on the evaluation value by the focus control device The method has a processing to perform.

When the focus control method is such a method, since the focus evaluation value is generated based on the contour correction signal output from the contour correction signal generation unit in the camera device, the contour correction is performed as in the conventional imaging device. Separately from the signal generating means, it is not necessary to provide a circuit for extracting a component corresponding to the contour correction signal in the focus control device. Therefore, the circuit configuration for realizing the autofocus function can be simplified, and the costs of the focus control device and the entire imaging device can be reduced.
Furthermore, since it is not a composite video signal but a focus evaluation value, that is, data, that is sent from the camera device to the focus control device, it is possible to prevent deterioration of the autofocus function characteristics.

As described above, according to the present invention, in the focus lens control device configured separately from the camera device, the focus evaluation value is transmitted from the camera device by an arbitrary communication method. The circuit configuration for realizing the autofocus inside can be simplified, and the cost of the focus control device can be suppressed.
In addition, since the focus evaluation value, not the composite video signal, is transmitted from the camera device to the focus control device, it is possible to prevent deterioration of the autofocus function characteristics.

  Hereinafter, preferred embodiments of an imaging apparatus and a focus control method according to the present invention will be described with reference to the drawings.

First, an embodiment of an imaging apparatus of the present invention will be described with reference to FIG.
FIG. 2 is a block diagram illustrating the configuration of the imaging apparatus according to the present embodiment.
As shown in the figure, the imaging device 1 includes a lens device 10, a camera device 20, a monitor device 30, and a focus control device 40. The camera device 20 and the focus control device 40 are separated from each other. It is configured to be connected by the cage communication means 50.

Here, the lens device 10 has the same configuration as the lens device 110 shown in FIG. 5, and a focus lens 11 for forming a subject image on an image sensor 21 (described later), and the focus lens 11. And a focus motor 12 for controlling the movement of the lens.
The camera device 20 includes an image sensor 21, a video signal processing circuit 22, an evaluation value detection unit 23, and an evaluation value transmission unit 24.
The image sensor 21 can be composed of, for example, a CCD (Charge-Coupled Device) and the like, photoelectrically converts the subject image formed by the focus lens 11, and outputs a video signal.

The video signal processing circuit 22 generates a composite video signal based on the output signal (video signal) of the image sensor 21 and sends it to the monitor device 30. Thereby, the monitor device 30 displays the subject image on the screen.
The video signal processing circuit 22 includes a contour correction generation circuit 25 that extracts a high frequency component of the video signal obtained from the image sensor 21 and generates a contour correction signal.
Specifically, as shown in FIG. 2, the contour correction generation circuit 25 includes a horizontal contour correction signal and vertical contour correction signal generation circuit (contour correction signal generation circuit) 25-1, and each generated contour correction signal. And a noise removal circuit 25-2 for removing noise components from the noise, and an addition circuit 25-3 for horizontal and vertical contour correction signals from which noise has been removed.

Note that a high-pass filter is configured in part of the contour correction generation circuit 25. For this reason, even when the camera device 20 includes the evaluation value detection means 23, it is not necessary to mount the high-pass filter 141-2 as shown in FIG.
Further, the trap filter 141-1 shown in FIG. 5 is used for attenuating the color signal component of the composite video signal. For this reason, it is not necessary to mount a trap filter in the generation part of the contour correction signal.
However, the peak detection means is one means that can constitute an evaluation value detection circuit. For this reason, the evaluation value detection means 23 with which the camera apparatus 20 is provided can also be comprised with a peak detection means. Note that the evaluation value detection means 23 in the present embodiment has the configuration shown in FIG. 3 as will be described later.

The evaluation value detection means 23 detects the contour correction signal as a focus evaluation value for every predetermined period. The configuration of the evaluation value detection means 23 is shown in FIG.
As shown in the figure, the evaluation value detection means 23 has an absolute value conversion circuit 23-1, a horizontal integration circuit 23-2, and a vertical integration circuit 23-3.
The absolute value conversion circuit 23-1 converts the contour correction signal from the contour correction generation circuit 25 into an absolute value. This is because the signal level of the contour correction signal has the same level of amplitude at the top and bottom centered on 0, so that the evaluation value becomes 0 when simply integrated (added). Therefore, it is possible to avoid the evaluation value from becoming 0 by providing the absolute value conversion circuit 23-1 in the previous stage of the integration circuit.

The horizontal integration circuit 23-2 integrates the contour correction signal every horizontal scanning period.
The vertical integration circuit 23-3 further integrates the contour correction signal integrated by the horizontal integration circuit 23-2 over one field or one frame. Thereby, a focus evaluation value, which is a signal representing the sharpness of the image, is obtained. This focus evaluation value is sent to the evaluation value transmitting means 24.
In the present embodiment, the horizontal integration circuit 23-2 and the vertical integration circuit 23-3 are collectively referred to as an “integration circuit”.
Further, when one of the integration circuits (the horizontal integration circuit 23-2 and the vertical integration circuit 23-3) or the evaluation value transmission unit 24 is an analog circuit and the other is a digital circuit, the integration circuit and the evaluation value transmission unit 24 An A / D conversion circuit or a D / A conversion circuit is provided between them.

The evaluation value transmitting means 24 sends the focus evaluation value from the integrating circuit to the focus control apparatus 40 by a communication method (communication means 50) in which the communication interface matches the evaluation value receiving means 41 (described later) of the focus control apparatus 40. Send.
As the focus evaluation value transmission means (communication means 50), any conventionally known suitable transmission means can be used. Specifically, for example, a method of preparing a command corresponding to transmission of an evaluation value and transmitting data by serial communication such as RS-232C or RS-442 can be used. Further, parallel communication can be used, and network communication such as IP transmission may be used.

The focus control device 40 includes an evaluation value receiving unit 41 and a focus control unit 42.
The evaluation value receiving unit 41 receives the focus evaluation value from the evaluation value transmitting unit 24 and sends it to the focus control unit 42.

The focus control means 42 performs a focusing operation by so-called hill-climbing autofocus, which adjusts the position of the focus lens 11 via the focus motor 12 so as to monitor the focus evaluation value and maximize the value. .
The focus operation by so-called hill-climbing autofocus performed by the focus control means 42 has the same control content as the conventional focus operation, and thus the description thereof is omitted here.

  In addition, when the distance from the camera device 20 to the focus control device 40 is long, the distance from the focus control means 42 to the focus motor 12 may be long. In this case, as shown in FIG. 4, the focus control device 40 includes a focus control value transmission unit 43, and the lens device 10 includes a focus control value reception unit 13, and transmits and receives the focus control value therebetween. It can be. Thereby, even when the distance between the focus control means 42 and the focus motor 12 is long, the focus lens can be controlled by sending the focus control value from the focus control device 40 to the focus motor 12.

Next, the procedure of the focus control method in the imaging apparatus according to the present embodiment will be described with reference to FIG.
A subject image is formed on the imaging element 21 of the camera device 20 by the focus lens 11 of the lens device 10 and photoelectrically converted. A video signal processing circuit 22 generates a composite video signal based on the video signal output from the image sensor 21 by this photoelectric conversion. The generated composite video signal is sent (output) to the monitor device 30, and the subject image is displayed on the screen.

On the other hand, based on the composite video signal, a contour correction signal is generated by the contour correction generation circuit 25 of the video signal processing circuit 22 and sent to the evaluation value detection means 23.
When the evaluation value detection unit 23 detects the focus evaluation value from the contour correction signal, the evaluation value detection unit 23 transmits the focus evaluation value to the focus control device 40 via the evaluation value transmission unit 24.
The focus evaluation value received by the evaluation value receiving unit 41 of the focus control device 40 is sent to the focus control unit 42. Thereby, the focus control device 42 controls the position of the focus lens 11 via the focus motor 12 based on the focus evaluation value.

According to the configuration and method described above, since the focus evaluation value is sent from the camera device to the focus control device, it is not necessary for the focus control device to include means for extracting the focus evaluation value from the composite video signal. For this reason, the circuit configuration for realizing autofocus in the focus control device can be simplified, and the cost of the focus control device can be suppressed.
In addition, since the focus evaluation value, not the composite video signal, is transmitted from the camera device to the focus control device, it is possible to prevent deterioration of the autofocus function characteristics.

The preferred embodiments of the imaging apparatus and the focus control method of the present invention have been described above. However, the imaging apparatus and the focus control method according to the present invention are not limited to the above-described embodiments, and are various within the scope of the present invention. Needless to say, it is possible to implement this change.
For example, in the above-described embodiment, the camera device and the focus control device are provided one by one. However, the configuration is not limited to one each, and a plurality of camera devices and focus control devices may be provided. In this case as well, the present invention can be applied.

  The present invention relates to autofocus control in an imaging apparatus in which a camera device and a focus control device are physically separated. Therefore, the present invention can be used in an apparatus having an autofocus function for controlling the position of the focus lens based on the focus evaluation value.

It is a block diagram which shows the structure of the imaging device of this invention. It is a block diagram which shows the structure of a contour correction production | generation circuit. It is a block diagram which shows the structure of the evaluation value detection means with which a camera apparatus is equipped. It is a block diagram which shows the other structure of the imaging device of this invention. It is a block diagram which shows the structure of the conventional imaging device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging device 10 Lens apparatus 11 Focus lens 12 Focus motor 13 Focus control value receiving means 20 Camera device 21 Imaging element 22 Video signal processing circuit 23 Evaluation value detection means 23-1 Absolute value conversion circuit 23-2 Horizontal integration circuit 23-3 Vertical integration circuit 24 Evaluation value transmission means 25 Contour correction generation circuit 25-1 Contour correction signal generation circuit 25-2 Noise removal circuit 25-3 Addition circuit 30 Monitor device 40 Focus control device 41 Evaluation value reception means 42 Focus control means 43 Focus Control value transmission means

Claims (6)

An imaging device in which a camera device that generates and outputs a composite video signal based on a subject image captured via a lens device and a focus control device that controls a focus lens of the lens device are separated from each other. ,
The camera device is
Contour correction signal generating means for generating a contour correction signal based on the composite video signal;
Evaluation value detection means for detecting an evaluation value based on the contour correction signal;
Transmission means for transmitting the evaluation value to the focus control device,
The focus control device is
Receiving means for receiving the evaluation value;
An imaging apparatus comprising: a focus control unit that controls the focus lens based on the evaluation value. The evaluation value detecting means is
An absolute value conversion circuit for converting the contour correction signal into an absolute value;
The imaging apparatus according to claim 1, further comprising: an integration circuit that integrates the contour correction signal converted into the absolute value and detects an evaluation value. The evaluation value detecting means is
The imaging apparatus according to claim 1, further comprising an analog-digital conversion unit and / or a digital-analog conversion unit between the integration circuit and the transmission unit. The integrating circuit is
The imaging apparatus according to claim 2 or 3, wherein the evaluation value is detected by integrating the contour correction signal for one field or one frame. Instead of the integration circuit,
The imaging apparatus according to claim 2, further comprising a maximum value detection circuit that detects a maximum value in one field or one frame of the contour correction signal as the evaluation value. A process of generating and outputting a composite video signal by a camera device based on a subject image captured via the lens device, and a process of controlling a focus lens of the lens device by a focus control device provided separately from the camera device A focus control method comprising:
In the camera device, processing for generating a contour correction signal based on the composite video signal;
In the camera device, a process of detecting an evaluation value based on the contour correction signal;
A process of transmitting the evaluation value to the focus control device in the camera device;
A process of receiving the evaluation value in the focus control device;
A process for controlling the focus lens based on the evaluation value in the focus control apparatus.

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