JPH10232339A - Focusing detector provided with power zoom function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the focusing detector of an AF camera excellent in handleability capable of avoiding the unfeasibleness of focusing and preventing middle omission by automatically performing zooming in an AF camera. SOLUTION: An arithmetic control part 6 judges according to range-finding information from a range-finding part 4 whether or not range-finding is feasible. In the case of judging that the range-finding is unfeasible, whether or not the range-finding is feasible is judged while zooming a lens to a wide side by a fixed amount. In the case of attaining a wide end, whether or not the range- finding is feasible is judged while zooming the lens to a telephoto side by the fixed amount after restoring it to a home position. When a range-finding feasible part is not found out, the unfeasibleness of the range-finding is displayed, and when a range-finding feasible position is found, the zoom lens is restored to the home position and focus is corrected, and then focusing display is performed. In the case of judging whether or not the middle omission occurs, the range- finding is performed by moving the lens to the wide side by the fixed amount even when the range-finding is feasible, and when the result of the range-finding is equal to or below a fixed value, a photographer selects either position by using a switch, and the focusing display is performed at a selected position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-focus detection apparatus having a power zoom function, and more particularly, to an in-focus detection apparatus capable of coping with an inability to measure distance or a dropout by changing a zoom position to measure a distance. The present invention relates to a focus detection device.

[0002]

2. Description of the Related Art In an AF camera of a type that detects a focus by using a phase difference or contrast, it is impossible to perform AF focusing when a subject in a target has no contrast. In such a case, there is a need for a technique of manually photographing with the focus position adjusted, or focusing on a subject having an equivalent distance of contrast and locking the focus, and then determining the composition and releasing. In addition, there is a case where a hollow spot occurs even when focusing is performed by AF, and it is not possible to determine whether or not the hollow spot occurs with a conventional camera. for that reason,
If the photographer does not need to change the focus position by judging the focus state by himself, shoot as it is, or if it is judged that there is a dropout, set the target on the subject to be focused and focus after It was necessary to lock the focus and return to the original composition for shooting, or to use a completely different composition to eliminate the hollowing-out state.

[0003]

An object of the present invention is to provide an AF
Provided is a focus detection device provided with an easy-to-use power zoom function that can reduce the probability of being unable to focus and perform a focusing operation after determining whether or not there is a possibility of a dropout in a camera. Is to do.

[0004]

In order to solve the above-mentioned problems, a focus detection apparatus according to the present invention comprises a zoom lens system, zoom lens driving means for driving the zoom lens system for zooming, and focusing on the zoom lens system. Focus lens driving means for bringing to a position, distance measuring means for photoelectrically converting a subject image obtained by the zoom lens system and outputting distance information, and when a zoom position set by a photographer cannot be measured,
The zoom lens system is moved from the zoom setting position to the wide side by a fixed amount at a time to determine whether or not distance measurement is possible. From the camera to the telephoto side by a fixed amount to determine whether or not distance measurement is possible.If a distance measurement possible position cannot be detected, a distance measurement disabled display is displayed. From the arithmetic control means for executing the distance measurement impossible reduction sequence for correcting the defocus generated between the distance-measurable zoom position and the originally set zoom position and performing the in-focus display. It is composed. Also,
In order to solve the above problems, the present invention provides a zoom lens system, a zoom lens driving unit that performs zoom driving of the zoom lens system, a focus lens driving unit that brings the zoom lens system to a focal position, and a zoom lens system. A distance measuring means for photoelectrically converting the obtained subject image to output distance information; and in a case where distance measurement is possible at a zoom position set by a photographer, an in-focus display is performed when the distance measurement result is smaller than a first predetermined distance. When the distance is larger than the first predetermined distance, the lens is moved to the wide side by a fixed amount, and as a result, when the distance is smaller than the second predetermined distance, it is determined that the hole is missing and the second distance is determined.
When the distance is longer than the predetermined distance, the control unit returns to the original zoom position and executes a centering prevention sequence for performing in-focus display. In the above configuration,
When the arithmetic and control unit determines that the image has a hollow area, the arithmetic and control unit has a switch unit that selects whether to focus on the zoom position based on the initial distance measurement result or the zoom position when the image is determined to be a hollow area. The focus display can be performed at the zoom position selected by the switch means. In order to further solve the above-described problem, the present invention determines whether or not a zoom position set by a photographer is distance-measureable. Are configured to execute the ranging impossible mitigation sequence, respectively. Furthermore, the present invention has a selection means for selecting a landscape mode for taking a distant view and a person mode for taking a close-up subject, and executes the ranging impossible reduction sequence when the distant view mode is selected, When the person mode is selected, it is possible to configure so as to execute a dropout prevention sequence.

[0005]

According to the above arrangement, for example, in an autofocus camera using a TTL phase difference detection method and having a built-in power zoom lens mechanism, the camera can be used when the in-focus position cannot be detected or the in-focus point is unnatural. It is possible to automatically change the angle of view to search for the in-focus zoom position or to indicate that the camera is in a hollow state, thereby improving the in-focus probability of the camera. Unable to detect the focus position occurs when the contrast change of the subject in the focus detection area is small or when the contrast change of the subject in the focus detection area is too small for the light receiving element. Hollowout occurs when a focus detection target enters between subjects to be focused.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a focus detection device having a power zoom function according to the present invention. This figure shows only the part directly related to the present invention, and other parts are omitted. The zoom lens system 9 includes a zoom lens unit 1 and a focus lens unit 2. The distance measuring unit 4 has an AF sensor, and outputs distance information (defocus amount) to a subject based on a signal obtained by photoelectrically converting an image formed by the zoom lens system 9. The arithmetic and control unit 6 controls the zoom lens driving circuit 3, the focus lens driving circuit 5, and the display circuit based on the subject distance information (ranging information) from the distance measuring unit 4 and the signals from the mode selection switch 10 and the zoom position selection switch 8. 7 is controlled.

[0007] The zoom position selection switch 8 is used to determine whether or not the zoom position initially set by the photographer is displayed when a hollow image is displayed.
This is a switch for selecting any one of the zoom positions at the time when the "missing" is displayed. The zoom position set previously is selected in the state where it is kept off, and when turned on, the zoom position at the time when the display of "missing" is selected. The mode selection switch 10 can select one of a landscape mode in which the depth of focus is increased for a long distance and a person mode in which the depth of focus is reduced for a short distance. When off, the landscape mode is selected, and when on, the portrait mode is selected. The zoom lens drive circuit 3 moves the zoom lens unit 9 by a motor (not shown) based on a zoom drive pulse from the arithmetic control unit 6 to perform an image enlargement and reduction operation.
The focus lens drive circuit 5 also moves the focus lens unit 2 by a motor (not shown) based on the drive pulse from the arithmetic control unit 6 to bring the focus lens unit 2 to a focus position.

FIG. 2A and FIG. 2B are flowcharts for explaining a sequence for reducing the inability to measure the distance of the focus detection device in FIG. When the power of the camera is turned on, the arithmetic and control unit 6 determines whether or not the distance can be measured at the zoom position set by the photographer based on the check signal by the photographer's operation of the check button (step (hereinafter referred to as "S") 201). . That is, the arithmetic and control unit 6 obtains the subject distance information from the distance measuring unit 4 and sends a drive pulse to the focus lens driving circuit 5 to move the focus lens 2 to the in-focus position.
If the in-focus position cannot be detected based on the obtained subject distance information, a distance measurement inability reduction sequence starting from S202 in FIG. 2A is entered, and it is determined whether the zoom position set by the photographer is the wide end (S202). .

If it is the wide end, the flow shifts to S210 to enter a sequence for zooming a fixed amount toward the telephoto side.
If it is not the wide end, a constant zoom drive pulse for driving to the wide side is output to the zoom lens drive circuit 3 (S203). Then, after moving the arithmetic control unit 6 by a certain amount, the distance measurement unit 6 performs distance measurement again to obtain distance information to the subject, and determines whether distance measurement is possible (S204). If the in-focus position cannot be detected, it is determined whether or not the zoom lens has reached the wide end (S208). If the zoom lens has not reached the wide end, the process returns to S203, and a fixed amount of zooming to the wide angle is performed in the same manner as described above. It is determined whether or not the distance is possible. This operation is repeated until the wide end is reached. FIG. 3 shows an example of the image change at this time. The case where the distance measurement is not possible in FIG. 3A is, for example, a case where the subject 11 has no contrast, and the contrast edge is captured in the detection area by zooming to the wide side as shown in FIG. 3B. Becomes possible.

In the above operation, when a focusable position is detected, the arithmetic and control unit 6 sends a drive pulse to the focus lens drive circuit 5 to bring the focus lens 2 to the focus position (S205). The focus lens driving circuit 5 outputs a zoom driving pulse to the zoom lens driving circuit 3 to return the zoom position to the originally set zoom position and to correct the defocus between the focus position and the originally set zoom position. Is driven (S206), and the display circuit 7 displays that the focus is different from the normal focus (S2).
07).

On the other hand, if the in-focus position cannot be detected before reaching the wide end, the arithmetic and control unit 6 sends a zoom drive pulse to the zoom lens drive circuit 3 to return to the original set zoom position (S209). A fixed zoom drive pulse is sent to drive the telephoto side from that position (S21).
0). After moving by a certain amount, the distance measurement unit 4 measures the distance to obtain distance information to the subject, and determines whether or not distance measurement is possible (S211). If the in-focus position cannot be detected, it is determined whether or not the telephoto end has been reached (S212). If the telephoto end has not been reached, the process returns to S210, and the telephoto side is zoomed by a fixed amount and measured in the same manner as described above. It is determined whether or not the distance is possible. This operation is repeated until the telephoto end is reached. FIG. 4 shows an example of an image change at this time. The case where the distance measurement is not possible in FIG. 4A is, for example, the case where the contrast edge of the subject 12 is too fine, and as shown in FIG. To an appropriate size.

If the focusable position is detected in the above operation, the flow shifts to S205, where the focus is driven as described above, and the focus is displayed (S206, S207). If the focusable position cannot be detected even when the telephoto end is reached, the arithmetic and control unit 6 outputs a zoom drive pulse to the zoom lens drive circuit 3 to return the zoom position to the originally set zoom position (S213). The display circuit 7 informs the photographer of the fact that zoom focusing is impossible, which is different from the above.

On the other hand, if it is determined in step S201 that the distance can be measured, the sequence enters a centering prevention sequence in FIG. The arithmetic control unit 6 determines that the distance measurement result, that is, the subject distance information is a predetermined distance a.
It is determined whether or not it is larger than (S215). If the distance is smaller than the predetermined distance a, a drive pulse is sent to the focus lens drive circuit 5 to bring the lens to the in-focus position and perform in-focus display (S224). If the distance measurement result is larger than the predetermined distance a, it is determined whether or not it is the wide end (S216).
If it is the wide end, a drive pulse is sent to the focus lens drive circuit 5 in the same manner as described above to bring the lens to the in-focus position and perform in-focus display (S224). If it is not the wide end,
A constant zoom drive pulse for driving the zoom lens drive circuit 3 to the wide side is output (S217). Then, after moving the arithmetic control unit 6 by a fixed amount, the distance measuring unit 6 is again moved.
To obtain distance information to the subject, and determine whether or not the distance measurement result is smaller than a predetermined distance b (S21).
8). Note that the distance b is smaller than a, and the distances a,
The most appropriate value is set for b in consideration of the shooting mode of the camera.

If the distance is longer than the predetermined distance b, it is determined whether or not it is the wide end (S219). If it is not the wide end,
Returning to S217, the zoom is again performed to the wide side by a fixed amount, and it is determined whether the zoom is smaller than a predetermined distance b. This operation is repeated until the wide end is reached. If the wide end has been reached, a zoom drive pulse is output to the zoom lens drive circuit 3 to return to the originally set zoom position (S223), and the display circuit 7 performs in-focus display to notify the photographer (S22).
4). If the result of the distance measurement is smaller than the predetermined distance b, the arithmetic and control unit 6 performs a hollow display on the display circuit 7 and stores this position (S220). The photographer can use the zoom position selection switch 8 to select one of the zoom position initially set and the zoom position when it is determined that the display is a blank display (S221).

When selecting the initially set zoom position (far side), the zoom position selection switch 8 is turned off,
When selecting the zoom position (near distance side) when it is determined that the display is a blank area, the display is turned on. When the arithmetic control unit 6 detects that the zoom position selection switch 8 is turned on, the arithmetic control unit 6 performs correction based on the zoom position at the stored position (distance measurement result) (S
222), the fact that the focusing has been achieved is displayed on the display circuit 7 (S224). Upon detecting that the zoom position selection switch 8 has been turned off, a zoom drive pulse is output to the zoom lens drive circuit 3 to return to the initially set zoom position (S22).
3) The focus is displayed on the display circuit 7 to notify the photographer (S224). FIG. 5 is a diagram showing an example of the image change at this time. When the target object is not in the focusable detection area as shown in FIG. 5A, the target object is captured in the focusable detection area by zooming to the wide side as shown in FIG. 5B. It becomes possible.

In the above embodiment, either the ranging impossible reduction sequence or the centering prevention sequence can be executed depending on whether or not ranging is possible at the initially set zoom position. May be executed in accordance with the photographing mode selected by the user. When the mode selection switch 10 shown in FIG. 1 is set to the landscape mode, a non-ranging reduction sequence can be executed, and when the mode selection switch 10 is set to the person mode, the dropout prevention sequence can be executed. When the landscape mode is selected, if the distance can be measured at the initially set zoom position, the in-focus display is performed at the zoom position without entering the distance measurement impossible reduction sequence. When the portrait mode is selected, if the distance cannot be measured at the initially set zoom position, if it is not the wide end, S
217.

[0017]

As described above, the present invention performs zooming when the distance cannot be measured at the zoom position initially set by the photographer, or when the distance can be measured but the zoom can be performed on the wide side. By checking whether or not the distance can be measured at the position, it is possible to reduce the number of cases in which focusing cannot be performed, and to prevent hollowing out beforehand. Therefore, if the in-focus detection device is mounted, an easy-to-use AF camera can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a focus detection device having a power zoom function according to the present invention.

FIG. 2A is a flowchart illustrating a sequence for reducing the inability to measure distance in the focus detection device of FIG. 1;

FIG. 2B is a flowchart for explaining a sequence for preventing a void in the focus detection device of FIG. 1;

FIG. 3 is a diagram for explaining a ranging impossible reduction sequence, and is a diagram showing an image when the camera is moved to a wide side from a set zoom position.

FIG. 4 is a diagram for explaining a ranging impossible reduction sequence, and is a diagram showing an image when moving from a set zoom position to a telephoto side.

FIG. 5 is a diagram for explaining a dropout prevention sequence.
FIG. 7 is a diagram illustrating an image when the zoom position is shifted from a set zoom position to a wide side.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Zoom lens unit 2 ... Focus lens unit 3 ... Zoom lens drive circuit 4 ... Distance measuring unit 5 ... Focus lens drive circuit 6 ... Calculation control unit 7 ... Display circuit 8 ... Zoom position selection switch 9 ... Zoom lens system 10 ... Mode Selection switch

Claims (5)

[Claims] A zoom lens system; a zoom lens driving unit that drives the zoom lens system to zoom; a focus lens driving unit that brings the zoom lens system to a focal position; and an object image obtained by the zoom lens system. A distance measuring means for converting and outputting distance information; and, when the zoom position set by the photographer cannot be measured, whether the distance can be measured by moving the zoom lens system by a fixed amount from the zoom set position to the wide side. If it is not possible to detect the distance-measurable position by moving to the wide side, then the camera will move from the originally set zoom position to the telephoto side by a fixed amount at a time to determine whether or not distance measurement is possible. When the position cannot be detected, the distance measurement disabled display is displayed.If the distance can be measured at any of the zoom positions, the zoom position returns to the original set zoom position, and the distance measurement possible zoom position and the original set zoom position are displayed. Focus detecting device including the resulting arithmetic control means for executing the distance measurement is impossible mitigation sequence for focus display corrects the defocus, a power zoom function, characterized in that consisted between. 2. A zoom lens system, a zoom lens driving unit for driving the zoom lens system to zoom, a focus lens driving unit for bringing the zoom lens system to a focal position, and a subject image obtained by the zoom lens system. A distance measuring unit that converts and outputs distance information; and if distance measurement is possible at a zoom position set by a photographer, a focus display is performed when the distance measurement result is smaller than a first predetermined distance; When the distance is larger than the distance, the lens is moved to the wide side by a fixed amount, and as a result, when the distance is smaller than the second predetermined distance, it is determined that the image is missing. When the distance is longer than the second predetermined distance, the original zoom position is set. A focus control device having a power zoom function, comprising: arithmetic control means for executing a centering prevention sequence for performing focus display by returning to. 3. A switch means for selecting, when the arithmetic control means determines that a focus is lost, to select one of a zoom position as an initial distance measurement result and a zoom position when it is determined that the focus is lost. The focus detection device with a power zoom function according to claim 2, wherein the arithmetic control means performs focus display at a zoom position selected by the switch means. 4. A zoom lens system, a zoom lens driving unit for driving the zoom lens system for zooming, a focus lens driving unit for bringing the zoom lens system to a focal position, and an object image obtained by the zoom lens system A distance measuring means for converting and outputting distance information; and determining whether or not a zoom position set by a photographer can be measured. If distance measurement is possible, a distance measurement result is smaller than a first predetermined distance. A focus display is performed, and when the distance is larger than the first predetermined distance, the lens is moved to the wide side by a fixed amount. As a result, when the distance becomes smaller than the second predetermined distance, it is determined that a hole is formed. If the distance remains large, the camera returns to the original zoom position and executes the centering prevention sequence to display the focus. If the distance cannot be measured, move the zoom lens system from the zoom setting position to the wide side. Moves a fixed amount at a time to determine whether or not distance measurement is possible.If it is not possible to detect a distance-measurable position due to wide-angle movement, then move a fixed amount from the originally set zoom position to the telephoto side for distance measurement. Judgment is made as to whether or not distance measurement is possible.If the distance measurement possible position cannot be detected, a distance measurement impossible display is displayed. And a calculation control means for executing a distance measurement impossible reduction sequence for correcting a defocus generated between the position and the originally set zoom position and performing in-focus display. Focus detection device provided. 5. A method for selecting a landscape mode for photographing a distant view and a portrait mode for photographing a subject at a short distance, wherein the arithmetic control means selects a distance measurement impossible sequence when the distant view mode is selected. 4. The focus detection apparatus with a power zoom function according to claim 3, wherein when the portrait mode is selected, a missing hole prevention sequence is executed.