JPS6269218A - Mountain climbing type automatic focusing device - Google Patents

Abstract

PURPOSE:To shorten the time required for focusing operation by limiting the range of movement of a focusing lens for focusing operation to a specific range corresponding to distance information obtained by an active distance measuring means. CONSTITUTION:A movement range setting means 14 regards a position where distance information outputted by an active distance measuring means 7 is given a margin on a common far point of accommodation side as the movement limit of the far point of accommodation side and a movement range is so set that the limit of a near point of accommodation side is regarded as the movement limit of design. Namely, far 2m distance information, a movement range setting means 14 operates so that the range shown by X between points C' having a margin on the far point of accommodation side for a point C, and A is set as the movement range of the focusing lens 2.

Description

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

As is well known, conventional technology autofocus devices detect contrast values from high-frequency components of video signals, drive a focusing lens in a direction that increases this contrast value, and then detect the peak point of the contrast value. When detected, the driving of the focusing lens is stopped to obtain a focused state.

Therefore, it is recognized as an excellent autofocus device because it does not require any special distance measuring means and has a simple configuration, and if it can reliably detect increases and decreases in the contrast value, it can obtain an extremely accurate focusing point. There is.

However, under special conditions, such as when the contrast value fluctuates unstable due to camera shake, or when the depth of field is shallow and the contrast value is small and its increase/decrease is small, the peak at which the combined state of contrast values can be obtained. Considering the conditions that make point detection difficult, this method has a disadvantage in principle that the proper stopping position of the focusing lens cannot be accurately detected.

Also, when considering the movement range and movement speed of the focusing lens itself, for example, considering the depth of field determined by subject brightness, focal length, and lens aperture value, it is possible to achieve sufficient focus by moving within a range less than the entire range of movement. Although there are cases where a focused state can be obtained, the entire movement range is usually set, that is, the movement is made possible at a predetermined speed over the entire movement range.

For this reason, for example, when changing from a relatively far subject to a subject 1 meter away, if the contrast value is small and its increase/decrease is small, the focusing lens may move in the wrong direction or pass the in-focus point. There is a risk that unnecessary operations will be performed, and furthermore, considering that the above operations are performed at a predetermined speed, it will take a long time to obtain a focused state, which will unnecessarily increase power consumption.

In addition, once the contrast value becomes unstable due to camera shake, etc., and the contrast value drops unstablely from the state where the in-focus state has been obtained, there is a risk that the above-mentioned behavior will occur, and in some cases, the peak point may differ from the peak point for the desired subject. There is also a risk that the peak point will be detected and the focusing lens will stop.

Therefore, in recent years, for example, the amount of incident light, the lens aperture value.

The driving range of the focusing lens is controlled by the focal length. In other words, the deeper the depth of field, the shorter the focal length, or the higher the brightness of the subject and the larger the lens aperture value, the greater the range of movement of the focusing lens. There have been proposals for automatic focus adjustment devices that narrow the range of movement of the focusing lens, and devices that divide the range of movement of the focusing lens into multiple parts so that they can be set arbitrarily (Japanese Patent Application Laid-Open No. Showa 58-19C1166
Publication No.

JP-A-58-45407, etc. ).

According to the former proposal, since the movement range of the focusing lens is narrowed due to the above-mentioned conditions, the movement time of the focusing lens can be shortened, and even if movement occurs due to camera shake, etc., the movement range of the focusing lens can be narrowed. This means that faster focusing operations can be expected compared to conventional autofocus devices.

Also, in the latter proposal, dividing the distance range in which focusing can be performed into multiple parts means that the focusing lens can be driven unconditionally at positions outside the above range, which ultimately limits the movement range of the focusing lens. Since the apparent stop movement range can be partially narrowed, it can be expected to speed up the focusing operation.

Problems to be Solved by the Invention However, in the former proposal, unless the movement range can be narrowed, for example, when the depth of field is shallow due to a long focal length, the contrast value will be Although the peak value becomes smaller and the detection of the peak value is rarely difficult and the in-focus state can be accurately obtained, the range of movement of the focusing lens becomes wider, resulting in the following problems.

In other words, as mentioned earlier, when changing from a relatively far subject to a subject 1 meter away, the focusing lens will move at a predetermined speed over almost the entire wide range of movement, resulting in a shorter focusing operation time. has the problem that it takes a long time.

In addition, the operation to return to the original position in the event of an unstable drop in contrast value due to camera shake, etc., will be performed over a wider range of movement, resulting in the long focusing operation described above. There is a risk that the focusing lens may stop at a position where another in-focus 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, there is no problem due to the difference in conditions as described above, but there is a risk of making a mistake in the range selection. If you make a mistake, you will not be able to get the in-focus state, and the focusing lens will continue to drive within the incorrect range.Furthermore, even if the above range selection is correct, the focusing lens will not be in focus until it reaches the selected range. The problem is that the selected range is different from the previous selected range, requiring a long focusing operation.

The present invention aims to improve the above-mentioned problems by limiting the movement range of the focusing lens in a mountain climbing type autofocus device to a predetermined range based on distance information obtained by an infrared triangulation method. It is an object of the present invention to provide an autofocus device which is characterized by the above-described features and further allows the focusing lens to be moved at a higher speed than the movement speed within the above-mentioned range when the focusing lens is located outside the above-mentioned range.

Means for Solving the Problems The mountain climbing type autofocus device according to the present invention includes an active distance measuring device that obtains distance information to a subject by emitting and receiving infrared light or transmitting and receiving ultrasonic waves, and a focus adjustment device. a motor for moving the focusing lens; a motor drive control means for controlling the operation of the motor; and a movement range setting for setting the movement range of the focusing lens based on the distance information obtained by the active distance measuring means. means for detecting the position of the focusing lens and outputting a focusing lens position signal; comparing the focusing lens position signal with the set movement range; and comparison means for operating the motor drive control means so that the motor is located within the set movement range.

Furthermore, in the mountain climbing type autofocus device according to the present invention, in the above configuration, the motor drive control means controls the motor to the first position when the focusing lens is located within the set movement range.
operation from the comparison means such that when the motor is outside the set movement range, the motor is driven at a second speed faster than the first speed in a direction in which the focusing lens moves within the set range. The device is configured to operate by receiving a control signal.

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

Furthermore, the focusing lens moves from outside the set movement range to within the set movement range at a faster speed.

Therefore, the focusing lens is less likely to move unnecessarily, and the focusing operation time is also shortened.

Embodiment FIG. 1 is a block diagram showing the basic configuration 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 attached to a camera device 4; is a motor drive control means for controlling the drive operation of this motor 1; 6 is a contrast value detection means for detecting a contrast value from the high frequency component of the video signal obtained from the camera device i14; 6 is a contrast value detected by the contrast value detection means 6 A motor control means detects an increase or decrease in the contrast value, moves the focusing lens 2 in the direction in which the peak point is obtained, and sends an operation control signal to stop the movement of the focusing lens 2 when the peak point is obtained. 3 shows the mountain climbing control means that outputs the output. The operation timing of the mountain climbing control means 6 is controlled by an output signal output from a comparison means 16, which will be described later.

7 is a light projecting/receiving unit 12 in an infrared projecting type triangulation distance measuring system, which is composed of an infrared projecting element 8, P, S, D, s, and a projecting/receiving lens 10.11 that emits and receives light in the form of a spot. The active distance measuring means is shown as a distance calculating means 13 which calculates the distance to the object by receiving the light receiving position output from the light emitting/receiving sections 120PJ and De, and outputs distance information to the object.

Reference numeral 14 indicates a moving range setting means for determining the moving range of the focusing lens 2 based on the distance information from the distance measuring device T.

16 is a focusing lens position detecting means for detecting the position of the focusing lens 2 and outputting a focusing lens position signal; 16 is a means for detecting the focusing lens position signal and the moving range set by the moving 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 is output for controlling the operations of the motor drive control means 3 and the mountain climbing control means 6 described above. 〇In this embodiment, the motor drive control means 3 described above controls the motor 1 based on 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. The drive speed can be set to two types.

Furthermore, since the movement range setting means 14 employs a triangulation type distance measurement means using P, S, and D as light receiving elements as an active type distance measurement means T, the movement range to be set will be described later. , the focusing lens 2 is operated from the drive limit position on the near point side to a slightly far point side position corresponding to the distance information obtained by the above-mentioned triangulation distance measuring means.

Regarding the operation of the mountain climbing type autofocus device according to the present invention, the basic configuration of which is shown in FIG. This will be explained with reference to FIG. 2, which is a so-called focusing characteristic diagram that is useful for explaining range characteristics. In FIG. It goes without saying that the design limit position on the point side is shown, and therefore the solid line shows the subject distance at which a focused state can be obtained when the focusing lens 2 moves from the point A to the point B.

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

Now, suppose that 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 should be positioned at the 0 point in Fig. 2. Although it is not necessary to set the range, the distance measuring method using triangulation using P, S, and D depends on the capabilities of P, S, and D, but the amount of reflected light from the subject may be similar to that of a typical subject. On the other hand, if the number is too small or too large, the operation of detecting the light receiving position becomes inaccurate and there is a disadvantage that distance information on the far point side or the near point side is output than the actual distance. It is not practical to control the movement of the focusing lens 2 only based on distance information indicating .

Therefore, the movement range setting means 14 in the present invention sets a movement limit on the far point side to a position where there is less margin on the far point side than the distance information output from the active distance measuring means 7, and sets the movement limit on the far point side. The movement range is set with the side limit as the designed movement limit.

That is, to explain with Figure 2, for distance information of 2 m, 0
The moving range setting means 14 according to the present invention operates so as to set the range indicated by X between point 07 and point A, which have a margin on the far point side, as the moving range of the focusing lens 2.

Similarly, the movement limit on the near point side remains unchanged, and the movement limit on the far point side is set for the subject distance obtained by the various distance measuring means 7. Such characteristics are explained in Fig. 2. The characteristics are 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 will be described in which a case is changed from photographing a 10 m object to a 2 m object.

When changing the subject as described above, the focusing lens 2 must be moved from point D, which is the focus position for a 10m subject in Figure 2, to point 0, which is the focus position for a 2m subject. On the other hand, when the above-mentioned subject is changed, the distance information output by the active distance measuring means A also changes, for example, 2t.
If object distance information called ri is output, as described above, the moving range setting means 14 will set X from point 07 to point A in FIG. 2 as the moving range of the focusing lens 2.

Next, the range X is compared with the focusing lens position signal outputted from the focusing lens position detecting means 15 by the comparing means 16. That is, point D, which is the in-focus position for the object at a distance of 10 m, is compared with the range X from point 07 to point A, and in this case, the comparing means 16 outputs an operation control signal indicating that the above point is outside the range X. is output to the motor drive control means 3 and the mountain climbing control means 6.

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

That is, since the subject has been changed, there is no need to perform a focusing operation from point D in Izutsu 2 to point 07 set by the movement range setting means 14, and there is no problem even if the focusing lens 2 is moved unconditionally. Since this does not occur, in this embodiment, the focusing lens '2 is moved by the moving range setting means 14.
If the value is outside the set range, the motor 1 is driven at a fast first speed to quickly move the focusing lens 2 within the range.

On the other hand, the mountain climbing control means 6, whose focusing operation is unnecessary as described above, is controlled to a non-operating state by being supplied with an operation control signal indicating outside the above-mentioned range from the comparison means 16. That will happen.

The focusing lens 2 moves at the first speed, and the comparing means 16
When an operation control signal indicating that the lens is within the range X is output, the motor drive control means 3 moves the focusing lens 2 within the range X at a second speed that is slower than the first speed. In addition, the mountain climbing control means 6 starts its operation, unlike the case where the focusing lens 2 is located outside the range, and the motor drive control means 3 moves to control the movement of the focusing lens 2. The operation will be controlled.

That is, once the focusing lens 2 enters the range set by the movement range setting means 14, which is the range indicated by is also slow when it is located out of range,
Moreover, the operation itself is controlled by the mountain peak control means 6.

As described above, the mountain climbing control means θ detects an increase or decrease in the contrast value output from the contrast value detection means 6,
The operation of the motor drive control means 3 is controlled to cause the motor 1 to move the focusing lens 2 in the direction in which the contrast value increases, and to stop driving the motor 1 when the peak point of the contrast value is obtained. Therefore, the focusing lens 2 stops moving at the 0 point in FIG. 2 where the focused state is obtained, and the series of focusing operations for changing the subject ends. So far, one operation of the basic configuration of the autofocus device according to the present invention has been described. For example, if the accuracy of the distance measurement information outputted by the active distance measurement means 7 can be improved, it will be possible to In the example above, the near point side movement limit, which was set as point A, which is the design movement limit point, is also made to correspond to the above-mentioned highly accurate distance information, and is set to an appropriate position with a little margin, for example, like the far point side limit described above. Needless to say, it can be set by the movement range setting means 14.

Furthermore, the movement range of the focusing lens 2 can be more narrowly limited by considering the depth of field as mentioned at the beginning, and FIG. FIG. 7 is a block diagram showing another embodiment of the mountain-climbing type autofocus device according to the present invention, which is set in consideration of depth.

In FIG. 3, the blocks with the same numbers as those in FIG. The depth of field detection means 18 outputs the distance information from the active distance measuring means 7 and the depth of field detection means 17.
A moving range setting means for setting the moving range of the focusing lens 2 in response to depth of field information from the camera is shown.

With such a configuration, the movement range of the focusing lens 2 is as shown by O, P, and Q, for example, as explained in FIG. 4, which is a focusing characteristic diagram corresponding to FIG. First, the range is A, which is the entire movement range of the focusing lens in Fig. 2,
This means that it can be set so that it can be regarded as between B and B.

Next, range setting similar to that described above, that is, range setting based on the distance information from the active distance measuring means 7, is performed. In other words, in the configuration shown in FIG. 3, the ranges O1P, Q
In each case, the range setting explained in FIG. 2 is further performed, and the setting movement range of the focusing lens 2 becomes narrower, and even if an unnecessary movement operation is performed, the operation period is This means it can be done in less time.

Regarding an example of the conditions for setting the ranges O, P, and Q mentioned above, for example, the range O is such that the focal length I is f-5.
At 0tm, the aperture value F is F=22, the range P is f=5c)m,
F=8 or f=35 m.

F=4. The range Q is set when f=76mm and F=1.4.

Effects of the Invention The mountain crest type autofocus device according to the present invention automatically adjusts the range in which the focusing lens 2 moves for focusing operation to a predetermined range corresponding to the distance information obtained by the active distance measuring means. Since it is limited, the range in which unnecessary movements may occur is narrowed, and the range in which the focusing operation by the mountain peak control means 6 is performed is limited to the necessary range, which is advantageous in terms of energy. This has the effect of It also has the effect of shortening the time required for operation.0 Furthermore, the range of movement of the focusing lens is limited by the depth of field information determined by the focal length and aperture value of the lens with the focusing lens. A sub-b expansion is also considered, and in such a case, it becomes possible to set a narrower movement range, and it also has the effect of making the above-mentioned effects even more effective.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the basic configuration of the mountain climbing type autofocus device according to the present invention, FIG. 2 is a focusing characteristic diagram for explaining the setting range by the movement range setting means 14 in FIG. 1, and FIG. The figure 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 movement range setting means 18 in FIG. 3. 0 1...Motor, 2...Focusing lens, 3
...Motor drive control means, 4...Camera device, 6...Contrast value detection means, 6.
... Mountain climbing control means, 7 ... Active distance measuring means, 8 ... Infrared light projecting element, 9 ...
...P, S, D, 1o... Light projection lens, 11
...... Light receiving lens, 12... Light emitting/receiving section,
13... Distance calculating means, 14... Moving range setting means, 16... Focusing lens position detecting means, 18... Comparing means, 17... . . . Depth of field detection means, 18 . . . Movement range setting means. Name of agent: Patent attorney Toshio Nakao and one other person
--Moon Soo 1 To 4th A 4th different cunning group

Claims (7)

[Claims] (1) A motor that moves a focusing lens that performs focus adjustment, a motor drive control means that controls the driving operation of the motor, and a camera device that outputs a video signal of a subject image obtained through the focusing lens, etc. a contrast value detecting means for detecting a contrast value from a high frequency component of the video signal; detecting an increase or decrease in the contrast value and moving the focusing lens in a direction in which the contrast value increases, and a point in time when a peak point thereof is obtained; a mountain climbing control circuit that outputs a control signal for stopping the focusing lens to the motor drive control means; an active distance measuring means that obtains distance information to the subject by emitting and receiving infrared light; a moving range setting means for setting a moving range of the focusing lens based on information; a focusing lens position detecting means for detecting the position of the focusing lens and outputting a focusing lens position signal; and a focusing lens position signal. and a set movement range set by the movement range setting means, and outputs an operation control signal indicating that the focusing lens is located within or outside the set movement range, and the motor drive control means and comparison means for supplying the data to the mountain climbing control means, which automatically sets a movement range of the focusing lens based on the distance information, and performs a comparison by the mountain climbing control means according to the set movement range. Mountain climbing type autofocus device that controls focusing operation. (2) The motor drive control means receives an operation control signal indicating that the position of the focusing lens is outside the set movement range, and operates the motor at a first speed and the focusing lens is within the set movement range. The motor is driven at a second speed slower than the first speed by receiving an operation control signal indicating that the focusing lens is within the set range. The mountain climbing type autofocus device according to claim 1, which is controlled to move only within a set movement range. (3) The mountain climbing control means becomes inactive upon receiving an operation control signal indicating that the position of the focusing lens is outside the set movement range, and becomes activated upon receiving an operation control signal indicating that the position of the focusing lens is within the set range. A mountain-climbing type autofocus device according to claim 1. (4) The movement range setting means sets a far point side limit position to a position with a margin on the far point side with respect to the supplied distance information, and sets a near point side limit position as a design limit to which the focusing lens can move. The mountain-climbing autofocus device according to claim 1, wherein a moving range of the focusing lens is set as a position. (5) A motor that moves a focusing lens that performs focus adjustment, a motor drive control means that controls the driving operation of the motor, and a camera device that outputs a video signal of a subject image obtained through the focusing lens, etc. a contrast value detecting means for detecting a contrast value from a high frequency component of the video signal; and detecting an increase or decrease in the contrast value and moving the focusing lens in a direction in which the contrast value increases and a peak point thereof is obtained. a mountain climbing control circuit that outputs a control signal for stopping the focusing lens at a certain point in time to the motor drive control means; an active distance measuring means that obtains distance information to the subject by emitting and receiving infrared light; Depth of field detection means for detecting a set focal length and aperture value of a lens attached to the camera device including a focusing lens, and outputting depth of field information determined by the set focal length and aperture value; a moving range setting means for setting a moving range of the focusing lens based on the information and the depth of field information; and a focusing lens position detecting means for detecting the position of the focusing lens and outputting a focusing lens position signal. and an operation control signal that compares the focusing lens position signal with a set movement range set by the movement range setting means and indicates that the focusing lens is located within or outside the set movement range. and a comparison means for outputting and supplying it to the motor drive control means and the mountain climbing control means, and automatically setting the movement range of the focusing lens based on the distance information, and according to the set movement range. A mountain-climbing type autofocus device that controls a focusing operation by the mountain-climbing control means. (6) The motor drive control means operates the motor at a first speed and the focusing lens is within the set movement range by receiving an operation control signal indicating that the position of the focusing lens is outside the set movement range. The motor is driven at a second speed slower than the first speed by receiving an operation control signal indicating that the focusing lens is within the set range. 7. The mountain-climbing autofocus device according to claim 6, which is controlled to move only within a set movement range. (7) The mountain climbing control means becomes inactive upon receiving an operation control signal indicating that the position of the focusing lens is outside the set movement range, and becomes activated upon receiving an operation control signal indicating that the position of the focusing lens is within the set range. The mountain climbing type autofocus device according to claim 5, which is in the state of the invention.