JPH07135593A - Automatic zoom device - Google Patents

Abstract

PURPOSE:To attain natural screen control by increasing the rising speed of a zoom mechanism. CONSTITUTION:The automatic zoom device is provided with an automatic focus mechanism 2 and a zoom mechanism 3 and is made up of a position detection part detecting the position of a focus lens, a position detection part detecting the position of the zoom lens, a ROM table 6 outputting object distance data based on the result of detection of both the position detection means, a preset part 8 setting in advance a referenced object distance, and a microcomputer 7 starting the control of the zoom mechanism 3 so as to discriminate a state to be nearly a focusing state when hunting in the vicinity of the focal position caused at the focus adjustment by the automatic focus mechanism 2 exceeds a setting number of times thereby controlling the size of the object.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auto zoom device suitable for use in, for example, a video camera.

[0002]

2. Description of the Related Art Some recent video cameras are equipped with a mechanism for automatically tracking a moving subject. With a video camera equipped with this automatic tracking mechanism, the subject can always be placed on the screen of the viewfinder, which is very convenient, for example, when the subject is himself / herself and he / she shoots.

A device having a function of automatically keeping the size of a subject in a screen substantially constant (hereinafter referred to as auto zoom) by combining such a technique with an autofocus mechanism and a zoom mechanism which are well known at present. The mechanism can be constructed relatively easily. A video camera equipped with such an auto-zoom device, for example, wants to shoot a scene in which a child as a subject competes, but since the distance from the shooting position gradually increases from the start position to the goal position, it is quite a continuous expression of the child's expression. It is convenient to use in situations where it is difficult to grasp the target.

The conventional auto-zoom device 1 shown in FIG.
The auto focus mechanism 2 and the zoom mechanism 3 are provided, and a focus lens position detection unit 4, a zoom lens position detection unit 5, a ROM table 6, a microcomputer 7, and a preset unit 8 are added for auto zoom. The switches S1 and S2 which are interlocked with each other are provided for switching between a manual zoom operation and an automatic zoom described later. Note that in this example, for convenience of explanation, the subject H
Although the automatic tracking mechanism for automatically tracking the subject is omitted, it is assumed that the subject H always enters the screen by the automatic tracking mechanism (not shown). Of course, the present technology can be used even when the subject H is manually tracked without an automatic tracking mechanism.

The autofocus mechanism 2 extracts a focus voltage from a video signal of a screen image of the subject H and automatically adjusts the focus lens 2a to a focus position based on the focus voltage. The optical image of the subject H coming through the focus lens 2a is converted into an electric signal by the image pickup device 2b, and becomes an image signal through the video process circuit 2c. The video signal becomes a focus voltage in which a predetermined high frequency component is extracted through the focus voltage extraction unit 2d. The focus voltage often uses a high frequency component extracted from a video signal in a focus area F set in a screen G shown in FIG. 4, for example. The microcomputer 2e inputs the focus voltage momentarily, and drives the focus lens 2a via the motor 2f based on the change of this value. The microcomputer 2e controls so that the highest point of the focus voltage is regarded as the focus position of the focus lens 2a. For example, as shown in FIG. 5, the focus is adjusted from the initial position (point P) to the focus position (point Q) by a hill climbing method. When performing, the hunting (mountain climbing and descending) is repeated in the vicinity of the focus position (point Q) several times and then converges to the final focus position (point Q).

The zoom mechanism 3 is for adjusting the size of the subject H (see FIG. 4) in the screen G by driving the zoom lens 3a, and based on the zoom information by pressing the zoom button B, the microcomputer 3b. Provides a control signal to the motor 3c to drive the zoom lens 3a along the optical axis direction. It should be noted that the non-lock type switch S1 interlocking with the zoom button B is provided between the zoom button B and the microcomputer 3b.
When 1 is in the position of the solid line, the zoom information from the zoom button B is input to the microcomputer 3b and the manual zoom operation is possible (manual zoom mode).
When the switch S1 is in the position of the alternate long and two short dashes line, the zoom information from the zoom button B is not input to the microcomputer 3b and the automatic zoom mode is set.

The auto-zoom function can be performed on the assumption that the subject H can always be focused, and a configuration for auto-zoom (focus lens position detection unit 4, zoom lens position detection unit 5, ROM table 6, microcomputer 7). The presetting unit 8) roughly calculates the ratio of the current subject distance to the initial subject distance, and automatically performs the zoom operation by the zoom amount corresponding to the calculation result.

The focus lens position detector 4 detects the position of the focus lens 2a, and the zoom lens position detector 5 detects the position of the zoom lens 3a. Note that these can be configured relatively easily by using well-known technology. The position information output from each of these position detectors 4 and 5 is input to the ROM table 6. R
The OM table 6 has object distance data corresponding to each combination of position information in advance, and outputs corresponding object distance data quickly as each position information is input momentarily. The subject distance data is always input to the microcomputer 7, and this may be input and set in the preset unit 8 in advance as reference distance data (representing the first subject distance) before the operation of controlling the size of the subject H. The non-lock type switch S2 interposed between the ROM table 6 and the preset unit 8 works in conjunction with the switch S1 described above. As shown in the figure, the switch S1 is switched from the solid line position to the alternate long and two short dashes line position for automatic zooming. When the mode is set, the switch S2 is also automatically switched from the solid line position to the alternate long and two short dashes line position, and the subject distance data is automatically stored and preset in the preset unit 8.

With such a preset operation, the automatic zoom becomes ready. Both the reference distance data stored in the preset unit 8 and the current object distance data are input to the microcomputer 7, and a control signal for controlling the size of the object H is supplied to the microcomputer 3b of the zoom mechanism 3 described above from these two data. Is output. The microcomputer 7 controls, for example, if the current subject distance data is doubled with respect to the reference distance data stored in the preset unit 8, the zoom magnification is also 2.
It is doubling. Similarly, if the current subject distance data changes to 1/2 times the reference distance data set by the preset unit 8, the zoom magnification is also 1/2 times. It should be noted that, instead of the automatic zoom being ready for the preset operation, for example, a mechanism may be added in which the automatic zoom is automatically set to the ready OK after the subject is automatically zoomed to a certain zoom position.

In the conventional auto zoom device 1, after the focus adjustment by the auto focus mechanism 2 is completely performed,
The auto zoom was started. Therefore, the microcomputer 2e of the autofocus mechanism 2 is set to output a control signal indicating this when the focus can be adjusted, and after receiving the control signal, the microcomputer 7 automatically zooms to the microcomputer 3b of the zoom mechanism 3. Was sending control signals for.

[0011]

However, in the case where the size control of the subject H (auto zoom) is started after the focus adjustment is completely performed like the conventional auto zoom device, the focus lens 2a is The zoom mechanism 3 is used in cases such as hunting near the focus position or when it takes time to reach the focus position.
The start-up was inevitably slow, and it was easy for an unnatural screen to appear.

[0012]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and provides the following auto-zoom device.

The focus voltage is extracted from the screen on which the subject is photographed, and the focus lens is automatically adjusted to the focus position by the hill climbing method based on the focus voltage, and the size of the subject in the screen is driven by the zoom lens. An automatic zoom device including a zoom mechanism for adjusting the position of the focus lens, comprising: first position detecting means for detecting the position of the focus lens; second position detecting means for detecting the position of the zoom lens; Distance information output means for outputting subject distance data from the detection results of the first and second position detecting means, preset means for setting reference subject distance data in advance via the distance information output means, and the automatic When the hunting near the focus position that occurs when adjusting the focus with the focus mechanism exceeds the set number of times, it is in a substantially focused state Determining, based on an output of said distance information output means for the output and the current of said preset means,
An automatic zoom device, comprising: a control unit that starts controlling the zoom mechanism so that the size of the subject in the screen is kept substantially constant.

The focus voltage is extracted from the screen on which the subject is photographed, and the focus lens is automatically adjusted to the focus position by the hill climbing method based on the focus voltage, and the size of the subject within the screen is driven by the zoom lens. An automatic zoom device including a zoom mechanism for adjusting the position of the focus lens, comprising: first position detecting means for detecting the position of the focus lens; second position detecting means for detecting the position of the zoom lens; Distance information output means for outputting subject distance data from the detection results of the first and second position detecting means, preset means for setting reference subject distance data in advance via the distance information output means, and the focus When the moving speed of the lens exceeds the set value, it is determined that it takes time to focus, and the output of the preset means is output. Based on an output of said distance information output means at the present time, auto zoom and wherein the constructed and control means starts to control the zoom mechanism to keep the size of the object substantially constant in the screen.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the auto-zoom device of the present invention, and FIG. 2 is a flow chart of a microcomputer which is a component of the auto-zoom device. In addition,
Since the basic configuration of the auto-zoom device of the present invention is the same as that of the conventional example shown in FIG. 3, the same components are designated by the same reference numerals to simplify the description.

The auto-zoom device 10 shown in FIG. 1 is provided with an auto-focus mechanism 2 and a zoom mechanism 3 as in the conventional example, and as shown in FIG. 4, the size of the subject H in the screen G is adjusted. In order to have a function (auto zoom) of automatically maintaining a substantially constant value, the focus lens position detection unit (first position detection unit) 4 and the zoom lens position detection unit (second position)
Position detection means) 5, ROM table (distance information output means) 6, microcomputer (control means) 7, and preset section (preset means) 8. The switches S1 and S2 that are interlocked with each other are for switching between a manual zoom operation and an automatic zoom described later.

The point of the present invention lies in how to speed up the start timing of controlling the size (auto zoom) of the subject H by the microcomputer 7 having a novel function. In addition, the microcomputer 2e that controls the focus adjustment in the autofocus mechanism 2 includes not only the control signal indicating that the focus adjustment is completely performed but also the speed data indicating the moving speed of the focus lens, as shown in FIG. As shown, hunting data representing the number of times of hunting (mountain climbing and descending) that occurs when focusing is performed by the hill climbing method is output.

Before starting the automatic zoom, the subject H is displayed on the screen G.
Switches S1, S2 to obtain the desired size in
Are set to solid line positions, and the zoom button B is used to perform a manual zoom operation. After this, switches S1 and S
When 2 is switched to the two-dot chain line position, the position of the focus lens and the position of the zoom lens at the desired zoom position are input to the preset unit via the ROM table, and the reference distance data (representing the first subject distance) ) Is set. In this way, the auto zoom operation is ready.

Thereafter, the reference distance data set by the preset unit 8 and the current object distance data output from the ROM table 6 are input to the microcomputer 7, and the microcomputer 7
Supplies a control signal for controlling the size of the subject H from these two information to the microcomputer 3b of the zoom mechanism 3. According to this control signal, the microcomputer 3b drives the motor 3c to perform the auto zoom operation.

The feature of the microcomputer 7 is that the focus lens 2
Even if a is not at the just focus position, the automatic zoom operation (the size control of the subject H in the screen G) is performed from before that. In doing this, the autofocus mechanism 2
The speed data and the hunting data obtained from the microcomputer 2e are used. Hereinafter, control of the zoom mechanism 3 by the microcomputer 7 will be described together with the flowchart shown in FIG.

When focus adjustment by the autofocus mechanism 2 starts from the start [step 1], it is determined whether or not the moving speed of the focus lens 2a is equal to or more than a set value [step 2]. This is because the moving speed of the focus lens 2a is relatively fast when the focus position is far, and relatively slow when the focus position is close, so whether or not it takes time to focus (in other words, the focus lens 2a moves from the focus position). This is for determining whether or not it is far.

When the moving speed of the focus lens 2a is equal to or higher than the set value [step 2 → Y], it is considered that it takes time to focus, and the position of the focus lens 2a and the position of the zoom lens 3a in the middle of movement are considered. The current subject distance is roughly obtained, the zoom direction (whether the subject H is enlarged or reduced) is determined from the ratio between the reference distance data and the current subject distance data [step 6], and the automatic zoom operation is started [step 7]. ]. On the other hand, when the moving speed of the focus lens 2a is lower than the set value [Step 5 → N], it is considered that focusing will not take so long, and the auto zoom operation is started according to the following procedure.

First, it is determined whether or not the focus lens 2a is in the just focus position [step 5]. If it is in the focus position [step 5 → Y], the zoom direction is determined [step 6], and the automatic zoom operation is started [step 7]. If it is not in the focus position [step 5 → N], it is determined whether or not the number of times of hunting that occurs near the focus position of the focus lens 2a exceeds the set number [step 8]. When the number of times of hunting exceeds the set number of times [step 8 → Y], it is regarded as a substantially focused state, the zoom direction is similarly determined [step 9], and the automatic zoom operation is started [step 10]. If the hunting count does not exceed the set count, click [Step 8 →
N], the process returns to step 5, and it is again confirmed whether or not the focus lens 2a is at the just focus position, and the procedure from step 5 onward is repeated.

In such an auto-zoom device 10, when the hunting near the focus position that occurs during focus adjustment exceeds the set number of times, it is determined that the hunting is substantially in focus, and the output of the preset unit 8 (reference distance data) and the output of ROM data (currently). Based on the subject distance data), the microcomputer 7 starts controlling the zoom mechanism 3 so as to keep the size of the subject H in the screen G substantially constant. There is a great advantage that it is possible to perform natural screen control more quickly than when an operation is performed.

Further, in the auto-zoom device 10, it is determined that it takes time to focus when the moving speed of the focus lens 2a exceeds a set value, and the output of the preset unit 8 (reference distance data) and the output of ROM data ( Based on (the subject distance at the present time), the microcomputer 7 uses the zoom mechanism 2 to keep the size of the subject H in the screen G substantially constant.
Therefore, even if the subject H moves very fast and cannot be followed by the autofocus mechanism 3, for example, there is an advantage that the screen can be controlled as naturally as possible.

[0027]

From the above description, the following effects can be expected in the auto zoom device of the present invention.

First, in the automatic zoom device according to the first aspect, when the hunting near the focus position that occurs during focus adjustment exceeds the set number of times, it is determined that the hunting is substantially in focus, and the output of the preset means (reference object distance data) is used. Based on the output of the distance information output means (subject distance data at the present time), the control means starts controlling the zoom mechanism so as to keep the size of the subject in the screen substantially constant, so that the focus is perfect as in the conventional case. There is a great advantage that the screen size can be controlled more quickly than when the size of the subject is controlled after the above condition, and natural screen control can be performed.

According to the second aspect of the present invention, when the moving speed of the focus lens exceeds the set value, it is determined that it takes time to focus, and the output of the preset means (reference object distance data) and the distance are set. Based on the output of the information output means (current subject distance data), the control means starts controlling the zoom mechanism so as to keep the size of the subject in the screen substantially constant. Even if the focus mechanism cannot follow, there is an advantage that it is possible to perform screen control as natural as possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an auto zoom device of the present invention.

FIG. 2 is a flowchart of a microcomputer that is a component of the auto zoom device.

FIG. 3 is a block diagram showing an embodiment of a conventional auto zoom device.

FIG. 4 is an explanatory diagram showing a state in which a subject is captured on the screen.

FIG. 5 is a diagram illustrating a hill-climbing autofocus mechanism.

[Explanation of symbols]

2 Auto Focus Mechanism 3 Zoom Mechanism 4 Focus Lens Position Detection Unit (First Position Detection Unit) 5 Zoom Lens Position Detection Unit (Second Position Detection Unit) 6 ROM Table (Distance Information Output Unit) 7 Microcomputer (Control Unit) 8 Preset Section (Preset Means) 10 Auto Zoom Device

Claims (2)

[Claims] 1. An autofocus mechanism for extracting a focus voltage from a screen on which a subject is photographed and automatically adjusting the focus lens to a focus position by a hill climbing method based on the focus voltage, and a zoom lens for the size of the subject in the screen. An auto-zoom device including a zoom mechanism that is adjusted by driving the first lens, a first position detecting unit that detects a position of the focus lens, and a second position detecting unit that detects a position of the zoom lens. From the detection results of the first and second position detecting means,
Distance information output means for outputting subject distance data, preset means for setting reference subject distance data in advance via the distance information output means, and hunting near the focus position that occurs during focus adjustment by the autofocus mechanism are set. When the number of times is exceeded, it is determined that the object is in a substantially focused state, and the zoom mechanism is controlled based on the output of the preset means and the output of the distance information output means at the present time so as to keep the size of the subject in the screen substantially constant. An auto-zoom device comprising a control means for starting. 2. An autofocus mechanism for extracting a focus voltage from a screen on which a subject is photographed and automatically adjusting the focus lens to a focus position by a hill climbing method based on the focus voltage, and a size of the subject within the screen. An auto-zoom device including a zoom mechanism that is adjusted by driving the first lens, a first position detecting unit that detects a position of the focus lens, and a second position detecting unit that detects a position of the zoom lens. From the detection results of the first and second position detecting means,
Distance information output means for outputting subject distance data, preset means for setting reference subject distance data in advance via the distance information output means, and time for focusing when the moving speed of the focus lens exceeds a set value. Based on the output of the preset means and the output of the distance information output means at the present time, the control means for controlling the zoom mechanism to keep the size of the subject in the screen substantially constant. An auto zoom device characterized by being configured.