JPH0628398B2 - Mountain climbing type autofocus device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autofocus device, and more particularly to a so-called mountain climbing type autofocus device that detects a contrast value from a high frequency component of a video signal and controls movement of a focusing lens. Is.

BACKGROUND ART As is well known, mountain climbing type autofocus devices detect a contrast value from a high frequency component of a video signal, drive a focusing lens in a direction in which the contrast value increases, and further determine the peak point of the contrast value. When detected, the driving of the focusing lens is stopped to obtain a focused state.

Therefore, the structure is simple without requiring any special distance measuring means, and if the increase or decrease in the contrast value can be reliably detected, an extremely accurate focus can be obtained, and it is recognized as an excellent autofocus device. There is.

However, a special condition, for example, when the contrast value fluctuates unstablely due to camera shake, or when the depth of field is shallow and the contrast value is small and the increase or decrease is small Considering the conditions that make it difficult to detect a point, there is a disadvantage in principle that the proper stop position of the focusing lens cannot be accurately detected.

Also, considering the moving range and moving speed of the focusing lens itself, for example, considering the subject brightness, the focal length, and the depth of field determined by the lens aperture value, it is sufficient to move in a range smaller than the entire range that can be moved. Although it may be possible to obtain a focus state, it is normally set within the entire movement range, that is, the movement is possible at a predetermined speed in the entire movement range.

For this reason, for example, when a relatively distant subject is changed to a subject of 1 m, if the contrast value is small and the increase / decrease is small, the focusing lens may erroneously move the focus lens or pass the focus point. Considering that the above operation is performed at a predetermined speed, it takes a long time to obtain the focused state, and power consumption is increased unnecessarily.

Further, once the contrast value becomes unstable from the state where the in-focus state is obtained due to camera shake or the like, the above-mentioned operation may be performed, and in some cases, a peak point different from the peak point for the desired subject may be detected. There is also a risk that the focusing lens will stop and the inconvenience will stop.

Therefore, in recent years, for example, the drive range of the focusing lens is controlled by the amount of incident light, the lens aperture value, and the focal length, that is, the depth of field is shorter and the focal length is shorter, or the subject brightness is higher and the lens aperture value is higher. The larger the size, the narrower the moving range of the focusing lens becomes.The automatic focusing device reduces the moving range of the focusing lens. The above devices have been proposed (JP-A-58-190165, JP-A-58-85407, etc.).

According to the former proposal, since the moving range of the focusing lens is narrowed due to the above-mentioned conditions, the moving time of the focusing lens is short, and the narrowed range is generated even if the moving due to camera shake occurs. Since the movement is performed in the interior, a quick focusing operation can be expected as compared with a general conventional autofocus device.

Also in the latter proposal, dividing the distance range in which focusing can be performed into a plurality means that the focusing lens can be driven unconditionally at a position outside the above range, and as a result, the range of movement of the focusing lens is increased. Apparently, it is possible to narrow a part of the entire movement range, that is, to narrow the range, and it can be expected to speed up the focusing operation.

Problems to be Solved by the Invention However, in the former proposal, when the depth of field becomes shallow, for example, when a long focal length is set, the contrast value becomes small except under the condition that the moving range can be narrowed. Although it becomes smaller and it becomes difficult to detect the peak value, the focusing state can be accurately obtained, but the moving range of the focusing lens is widened, which causes the following problems.

That is, as described above, when changing from a relatively distant subject to a subject of 1 m, the focusing lens moves at almost the entire widened moving range at a predetermined speed, and the focusing operation time is It has a problem that it takes a long time.

In addition, when the contrast value is unstablely lowered due to camera shake or the like, the returning operation to the original position is also performed in the wider movement range, which is the above-described long-time focusing operation. There is a risk that the focusing lens may stop at a position where another focused state cannot be obtained.

On the other hand, in the latter proposal, since the selection of the range in which the focusing operation can be performed is arbitrary, the problem due to the difference in the conditions as described above does not occur, but the range selection may be erroneous, If you make a mistake, the in-focus state will not be obtained, and the focusing lens will continue to drive in the wrong range.Furthermore, even if the above range is correctly selected, until the selected range is reached, There is no difference from the device, that is, the farther the selection range is from the previous selection range, the longer the focusing operation is required.

The present invention is intended to solve the above-mentioned problems, and the moving range of a focusing lens in a mountain climbing type autofocus device is based on distance information obtained by an active distance measuring unit such as an infrared triangulation type. An object of the present invention is to provide an autofocus device which is characterized by being limited to a predetermined range, and when the focusing lens is located outside the above range, it can be moved at a speed higher than the moving speed within the above range.

Means for Solving Problems A mountain climbing type autofocus device according to the present invention comprises an active distance measuring means for obtaining distance information to a subject by an infrared light projecting / receiving operation or ultrasonic wave transmission / reception, and focus adjustment. A motor for moving the focusing lens, a motor drive control means for controlling the operation of the motor, and a moving range setting for setting the moving range of the focusing lens based on the distance information obtained by the active distance measuring means. Means, a focusing lens position detecting means for detecting a position of the focusing lens and outputting a focusing lens position signal, and the focusing lens position signal and the set moving range are compared, Is provided with a comparison means for operating the motor drive control means so as to be positioned within the set movement range.

Further, in the mountain climbing type autofocus device according to the present invention, in the above configuration, the motor drive control means sets the motor to the first position when the focusing lens is located within the set movement range.
When the speed is out of the set range, the comparison means operates so as to drive the motor at a second speed higher than the first speed in the direction in which the focusing lens moves toward the set range. It is configured to operate by receiving a control signal.

Operation Since the mountain climbing type autofocus device according to the present invention has the above-mentioned configuration, the moving range of the focusing lens is automatically set by the active distance measuring means and the moving range setting means.

Further, the movement of the focusing lens from outside the set movement range to within the set movement range is performed at a higher speed.

Therefore, the focusing lens is less likely to be moved unnecessarily, and the focusing operation time is shortened.

Embodiment 1 FIG. 1 is a block diagram showing the basic structure of a mountain climbing type autofocus device according to the present invention, in which 1 is a motor for moving a focusing lens 2 in a lens mounted on a camera device, 3 Is a motor drive control means for controlling the drive operation of the motor 1, 5 is a contrast value detection means for detecting a contrast value from a high frequency component of a video signal obtained from the camera device 4, and 6 is a contrast value detection means 5
An operation control signal for detecting an increase or decrease in the contrast value detected by, moving the focusing lens 2 in the direction in which the peak point is obtained, and stopping the movement of the focusing lens 2 when the peak point is obtained. Motor control means 3
It shows a mountain climbing control means for outputting to. The operation of the mountain climbing control means 6 is controlled by the output signal output from the comparison means 16 described later.

Reference numeral 7 designates an infrared light emitting element 8, a PSD 9 and a light emitting and receiving section 12 in the infrared light emitting type triangulation distance measuring system comprising a light emitting lens 10 and 11 for forming a light emitting and receiving area in a spot shape, and a PSD 9 of this light emitting and receiving section 12. 1 shows an active distance measuring means comprising a distance calculating means 13 which calculates a subject distance by receiving the light receiving position output in and outputs distance information to the subject.

Reference numeral 14 denotes a moving range setting means for receiving the distance information from the distance measuring device 7 and determining the moving range of the focusing lens 2.

Reference numeral 15 denotes a focusing lens position detecting means for detecting the position of the focusing lens 2 and outputting a focusing lens position signal, and 16 denotes the focusing lens position signal and the movement range set by the movement range setting means 14. Based on the comparison result, that is, whether or not the current focusing lens position is within the set movement range, an operation control signal for controlling the operations of the motor drive control means 3 and the mountain climbing control means 6 is output. The comparison means is shown.

In the present embodiment, the motor drive control means 3 described above sets the drive speed of the motor 1 to two types by the operation control signal based on the comparison result of the comparison means 16 indicating the position of the focusing lens 2 with respect to the set movement range. It can be set.

Further, since the moving range setting means 14 employs a triangulation type distance measuring means using a PSD as a light receiving element as the active type distance measuring means 7, the moving range to be set will be described later, but the focusing lens will be described later. It is operated so as to be from the driving limit position on the near point side of 2 to a position on the far point side of the position corresponding to the distance information obtained by the distance measuring means of the triangulation method.

Hereinafter, regarding the operation of the mountain climbing type autofocus apparatus according to the present invention, the basic configuration of which is shown in FIG. 1, one relationship between the focus lens position and the subject distance at which the focus state is obtained is shown and set by the moving range setting means 14. Description will be given with reference to FIG. 2, which is a so-called focusing characteristic diagram for explaining the movement range characteristic.

In FIG. 2, points A and B are the focusing lens 2 respectively.
The designable limit position on the near point side or far point side that can be moved is shown. Therefore, the solid line from the point A to the point B is the focusing lens 2
Needless to say, it indicates the subject distance at which the in-focus state can be obtained when is moved.

Now, regarding the operation, the operation of the moving range setting means 14 will be described first.

Now, assuming that the distance information indicating 2 m is obtained by the operation of the active distance measuring means 7, if this 2 m is an accurate value, the focusing lens 2 can be moved if it is located at point C in FIG. Although it is not necessary to set the range, if the distance measurement method of the triangulation method using PSD9 depends on the ability of PSD, if the amount of reflected light from the subject is less or more than that of a general subject However, there is a disadvantage that the operation of detecting the light receiving position becomes inaccurate and the distance information on the far point side or the near point side is output from the actual distance, and therefore the focusing lens based on only the distance information indicating 2 m described above. Two
The movement control of is not practical.

For this reason, the moving range setting means 14 in the present invention sets the position at which the co-distant point side has a small margin to the distance information output from the active distance measuring means 7 as the far point side moving limit, and the near point. The movement range is set with the side limit as the designed movement limit.

That is, referring to FIG. 2, for distance information of 2 m, C
The moving range setting means 14 according to the present invention operates so as to set, as the moving range of the focusing lens 2, the range indicated by X between the point C'and the point A, which has a margin on the far side with respect to the point. .

Similarly, the movement limit on the near point side remains the same, and the movement limit on the far point side is set for the object distance obtained by various distance measuring means 7. Such characteristics will be described with reference to FIG. The characteristic is as shown by the broken line.

Now, regarding the operation of the autofocus device according to the present invention, for convenience of explanation, a case where a subject of 10 m is being photographed is changed to a subject of 2 m will be described.

When the subject is changed as described above, the focusing lens 2 must be moved from point D, which is the focusing position for the subject of 10 m in FIG. 2, to point C, which is the focusing position for the subject of 2 m. I have to.

On the other hand, when the subject is changed as described above, the distance information output from the active distance measuring unit 7 also changes, and is 2 m, for example.
If the subject distance information is output, as described above, the movement range setting means 14 sets X as the movement range of the focusing lens 2 from point C'to point A in FIG.

Next, the range X is compared with the focusing lens position signal output from the focusing lens position detecting means 15 by the comparing means 16. That is, the point D, which is the in-focus position for the subject of 10 m, is compared with the range X from the point C ′ to the point A. In such a case, the comparison means 16 performs the operation control indicating that the point D is outside the range X. The signal is output to the motor drive control means 3 and the mountain climbing control means 6.

The motor drive control means 3 is operation-controlled by receiving an operation control signal indicating the outside of the above range, and first, in order to move the focusing lens 2 into the above range X, a fast first
The motor 1 is driven at the speed of.

That is, since the subject has been changed, it is not necessary to perform the focusing operation from the point D in the second position to the point C ′ set by the moving range setting means 14 even if the focusing lens 2 is unconditionally moved. Since no problem occurs, in this embodiment, when the focusing lens 2 is out of the range set by the moving range setting means 14, the focusing lens 2 is swiftly moved into the above range at the high first speed. That is, the motor 1 is driven.

On the other hand, the mountain climbing control means 6 does not need the focusing operation as described above, and is controlled to the inoperative state by the operation control signal indicating the outside of the range described above being supplied from the comparison means 16. become.

When the focusing lens 2 moves at the upper first speed and the operation control signal indicating that the comparison unit 16 enters the range X is output, the motor drive control unit 3 causes the motor drive control unit 3 to operate at the first speed. The focusing lens 2 is moved only within the range X at the slower second speed, and the mountain climbing control means 6 starts the operation unlike the case where the mountain climbing control unit 6 is located outside the range. Then, the operation control of the motor drive control means 3 is performed to control the movement of the focusing lens 2.

That is, once the focusing lens 2 enters the range set by the moving range setting means 14, that is, the range indicated by X in the above-mentioned example, the moving operation thereafter is limited to the set range and the speed thereof is increased. Is slower than when it is out of range,
Moreover, the operation itself is controlled by the mountain climbing control means 6.

The mountain climbing control means 6 detects increase or decrease in the contrast value output from the contrast value detection means 5 as described above,
The focusing lens 2 is moved by the motor 1 in the direction of increasing the contrast value, and the operation of the motor drive control means 3 is controlled so as to stop the driving of the motor 1 when the peak point of the contrast value is obtained. Therefore, the focusing lens 2 stops moving at the point C in FIG. 2 in which the focused state is obtained, and the series of focusing operations for changing the subject is completed. That is why.

The operation of the basic configuration of the autofocus device according to the present invention has been described above. For example, if the accuracy of the distance measurement information output from the active distance measuring means 7 can be increased, the movement limit in the design in the previous example will be described. The moving limit on the near point side, which is the point A, is also made to correspond to the high-precision distance information, and is set to the moving range setting means 14 at an appropriate position with a little margin like the far point side limit described above. Needless to say, it can be set by.

Further, the moving range of the focusing lens 2 can be limited more narrowly in consideration of the depth of field as described at the beginning, and FIG. 3 shows the moving range of the focusing lens 2 in the field. FIG. 9 is a block diagram showing another embodiment of a mountain climbing type autofocus device according to the present invention, which is set in consideration of depth as well.

In FIG. 3, those having the same numbers as those in FIG. 1 indicate the same functional blocks, and 17 detects the set focal length and aperture value of the lens L mounted on the camera device 4 and outputs the depth of field information. Depth-of-field detection means 18 for performing distance information from the active type distance-measuring means 7 and the depth-of-field detection means 17 are provided.
The moving range setting means for receiving the depth of field information from and setting the moving range of the focusing lens 2 is shown.

With such a configuration, the range of movement of the focusing lens 2 will be, for example, ranges indicated by O, P, and Q when described with reference to FIG. 4 which is a focusing characteristic diagram corresponding to FIG. First, the total moving range A of the focusing lens in FIG.
It can be set so that it can be regarded as between B.

Next, the same range setting as that described above, that is, the range setting based on the distance information from the active distance measuring means 7 is performed.

That is, in the configuration shown in FIG. 3, ranges O, P, Q
Since the range setting described in FIG. 2 is further performed in each of the above, the set moving range of the focusing lens 2 becomes narrower, and even if an unnecessary moving operation is performed, the operating period is It will be possible to make it shorter.

An example of the conditions for setting the ranges of O, P, and Q described above will be described. For example, in the range O, the focal length f is f = 5.
At 0 mm, the aperture value F is F = 22, the range P is f = 50 mm, F =
8 or f = 35 mm, F = 4, range Q is f = 75 mm,
It will be set when F = 1.4.

The mountain climbing type autofocus device according to the present invention automatically limits the range in which the focusing lens 2 moves for the focusing operation to a predetermined range corresponding to the distance information obtained by the active distance measuring means. Therefore, there is an effect that the range in which an unnecessary operation may occur is narrowed, and the range in which the focusing operation by the mountain climbing control means 6 is performed is only the necessary range, which is advantageous in terms of energy. In addition, the moving speed of the focusing lens is set to be faster when the focusing lens is located outside the above predetermined range than when the focusing lens is located within the range. It also has the effect of being able to do so.

Further, it may be possible to expand the range of movement of the focusing lens according to the depth of field information that is determined by the focal length of the lens having the focusing lens and the aperture value. In such a case, a narrower range of movement may be set. This is possible, and also has the effect of making the above-described effect more effective.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of a mountain climbing type autofocus device according to the present invention, FIG. 2 is a focusing characteristic diagram for explaining a setting range by a moving range setting means 14 in FIG. 1, and FIG. FIG. 4 is a block diagram showing another embodiment of the mountain climbing type autofocus device according to the present invention, and FIG. 4 is a focusing characteristic diagram for explaining the setting range by the moving range setting means 18 in FIG. There is. DESCRIPTION OF SYMBOLS 1 ... Motor, 2 ... Focusing lens, 3 ... Motor drive control means, 4 ... Camera device, 5 ... Contrast value detection means, 6 ... Mountain climbing control means, 7 ... Active distance measuring means , 8 ... Infrared projector, 9 ... PSD, 10 ...
Emitter lens, 11 ... Receiving lens, 12 ... Emitter / receiver section,
13 ... distance calculation means, 14 ... movement range setting means, 1
5 ... Focusing lens position detection means, 16 ... comparison means, 1
7 ... Depth of field detecting means, 18 ... Moving range setting means.

Claims (7)

[Claims] 1. A motor for moving a focusing lens for focus adjustment, a motor drive control means for controlling a driving operation of the motor, and a video signal of a subject image obtained through the focusing lens and the like. Contrast value detecting means for detecting a contrast value from the high frequency component of the video signal of the camera device, and detecting the increase or decrease of the contrast value, moving the focusing lens in the direction of increasing the contrast value, and obtaining the peak point thereof. A mountain climbing control means for outputting a control signal for stopping the focusing lens to the motor drive control means at a given time, and an active distance measuring means for obtaining distance information to a subject by an infrared light projecting / receiving operation or the like. A moving range setting means for setting a moving range of the focusing lens based on the distance information, and a focusing range for detecting the position of the focusing lens. The focusing lens position detecting means for outputting a position signal is compared with the focusing lens position signal and the set moving range set by the moving range setting means, and the focusing lens is within or outside the set moving range. It is provided with a comparison means for outputting an operation control signal indicating that the focusing lens is located at the motor drive control means and the mountain climbing control means, and the range of movement of the focusing lens is automatically detected by the distance information. Mountain climbing type auto-focusing device for controlling the focusing operation by the mountain climbing control means according to the set moving range. 2. The motor drive control means receives the operation control signal indicating that the position of the focusing lens is out of the set movement range so that the motor is at the first speed and the focusing lens is in the set movement range. The focusing lens is driven so as to move inward and the motor is driven at a second speed lower than the first speed by receiving an operation control signal indicating that the motor is in a set range. The mountain climbing type autofocus device according to claim 1, wherein the control is performed so that the lens moves only within the set moving range. 3. The mountain climbing control means receives an operation control signal indicating that the position of the focusing lens is outside the set movement range, becomes inoperative, and receives an operation control signal indicating that the position is within the set range. The mountain climbing type autofocus device according to claim 1, which is brought into an operating state by the above. 4. The moving range setting means is designed such that a position having a margin on the far point side with respect to the supplied distance information is a far point side limit position, and the focusing lens can move at the near point side limit position. The mountain climbing type autofocus device according to claim 1, wherein a moving range of the focusing lens is set to be a limit position of. 5. A motor for moving a focusing lens for focus adjustment, a motor drive control means for controlling a driving operation of the motor, and a video signal of a subject image obtained through the focusing lens and the like. Contrast value detecting means for detecting a contrast value from the high frequency component of the video signal of the camera device, and detecting the increase or decrease of the contrast value, moving the focusing lens in the direction of increasing the contrast value, and obtaining the peak point thereof. A mountain climbing control means for outputting a control signal for stopping the focusing lens to the motor drive control means at a given time, and an active distance measuring means for obtaining distance information to a subject by an infrared light projecting / receiving operation or the like. , Detecting a set focal length and an aperture value of a lens attached to the camera device, including the focusing lens, and determining the set focal length and aperture value. Depth-of-field detection means for outputting depth-of-field information determined according to the above-mentioned information, moving range setting means for setting a moving range of the focusing lens based on the distance information and the depth-of-field information, and the focusing. Focusing lens position detecting means for detecting the position of the lens and outputting a focusing lens position signal;
The focusing lens position signal is compared with the set moving range set by the moving range setting means, and an operation control signal indicating that the focusing lens is located within the set moving range or outside the set moving range is obtained. Comparing means for outputting and supplying to the motor drive control means and the mountain climbing control means, the moving range of the focusing lens is automatically set by the distance information and the depth of field information, A mountain climbing type autofocus device for controlling a focusing operation by the mountain climbing control means according to the set movement range. 6. The motor drive control means receives the operation control signal indicating that the position of the focusing lens is out of the set movement range so that the motor is at the first speed and the focusing lens is in the set movement range. The focusing lens is driven so as to move inward and the motor is driven at a second speed lower than the first speed by receiving an operation control signal indicating that the motor is in a set range. The mountain climbing type autofocus device according to claim 5, wherein the control is performed so as to move only within the set movement range. 7. The mountain climbing control means receives an operation control signal indicating that the position of the focusing lens is out of the set movement range, becomes inoperative, and receives an operation control signal indicating that it is within the set range. The mountain climbing type autofocus device according to claim 1, which is brought into an operating state by the above.