JP3035370B2 - Distance measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active distance measuring apparatus suitable for an auto-focus camera, which measures a distance to a subject by projecting a signal light and receiving the reflected signal light. It relates to the improvement of.

[0002]

2. Description of the Related Art In an auto-focus camera or the like, a so-called active method in which a signal light is projected onto a subject and the signal light reflected by the subject is received and the distance to the subject is measured based on the principle of triangulation. The distance measuring device
It has been widely used.

As shown in, for example, Japanese Patent Publication No. 54-39731 and Japanese Patent Application Laid-open No. Sho 60-19116, a pair of silicon photocells (SPC) divided into two parts are used as light receiving means. In addition, a distance measuring device capable of measuring a distance without a movable part has been widely put into practical use.

FIG. 9 shows a conventional active distance measuring apparatus.
The signal light from the light emitting element 21 is focused to a predetermined light amount by the stop 22 and then is focused by the light projecting lens 23 to a distance L2 point. When the subject 24 exists at the point L2, the signal light from the light emitting element 21
And is imaged at a spot position c on the light receiving sensor 27 via the light receiving lens 25 and the diaphragm 26.

Similarly, when the subject 24 is located at the position L1 (short distance), the spot position n on the light receiving sensor 27
Further, when the subject 24 exists at the position of L3 (far distance), an image is formed at the spot position f on the light receiving sensor 27.

The spot position n,
The distance to the subject is obtained by detecting c and f and calculating them. The focal position of the light receiving lens 25 (the distance at which a sharp image is formed on the light receiving sensor 27) is L2
It has been adjusted to

[0007]

FIG. 10 shows a spot image formed on the light receiving sensor 27 in the distance measuring apparatus thus configured. As shown in FIG.
Since the focal length of No. 5 is sharply formed as a spot image C at the position of the subject distance L2, when the subject exists at L1 or L3,
As L1 and L3 move away from L2, the light receiving sensor 27
The upper spot image is blurred and enlarged like N or F. At this time, the distance measurement data for the position of the center of gravity of the spot image on the light receiving sensor 27 is a straight line like a dotted line as shown in FIG. 11 showing the relationship between the distance to the subject and the distance measurement data. However, if the spot image is blurred and deviates from the light receiving sensor 27, the position of the center of gravity does not move with respect to the change in the distance, and the linearity is lost as shown by the solid line.

If the focal length of the photographing lens extends to the telephoto side, the distance measuring capability of the distance measuring device is required in a wider range, but the required distance measuring accuracy cannot be obtained due to the bending on the long distance side. Therefore, the distance measuring ability cannot be satisfied. In addition, the distance measurement accuracy on the short distance side becomes improper due to the bending on the short distance side, and even if it is taken, the photograph becomes blurred or the close warning range is set to prevent blurring. I had to be far away.

Japanese Patent Laid-Open Publication No. Sho 59-195631 discloses a technique for automatically switching between a normal photographing mode and a close-up photographing mode based on the result of distance measurement.

However, in this case, the light receiving lens is divided into a main lens unit for measuring a distance during normal photographing and an auxiliary lens unit for macro photographing, and a mask is provided for the two light receiving lenses based on the distance measuring distance. Since the method of covering one of the light receiving lenses is different, even if the signal of one light receiving sensor is the same, the subject distance is different for normal shooting and macro shooting. The macro lens must be inserted, and the structure is complicated and the camera body becomes large, which is troublesome. In addition, the relationship between the spot position on the light receiving sensor by each optical system and the subject distance must be set separately, and adjustment and correction must be performed, which impairs mass productivity. Furthermore,
In the light receiving lens at the time of macro shooting, the blur and size of the spot image are not taken into consideration within the range, and similarly, the problem of the short distance side bending has occurred.

The present invention has been made in view of the above circumstances, and improves the distance measurement capability and the distance measurement accuracy, and has a predetermined function.
The distance from the first distance maintained at the distance measurement characteristic differs from the first distance.
Useless spot image in a predetermined range up to a second distance
The operation for changing the distance is not performed.
It is possible to provide a distance measuring device that can be used.

[0012]

Means for Solving the Problems To achieve the above object,
The present invention is directed to projecting a projected spot image toward an object.
Light emitting means, and the light emitting switch emitted from the light emitting means.
Light reflected from the object in the pot image as a received light spot image
Light receiving means for receiving light, and a light receiving signal from the light receiving means
In a distance measuring device that detects the distance to the object by
According to the distance to the object, the light emitted by the light emitting means is projected.
Light spot image and light receiving spot image received by the light receiving means
Change the size of at least one of
The image variable means and the distance to the target object have a predetermined distance measurement characteristic.
A second distance different from the first distance maintained from the first distance
If the spot is within a predetermined range up to the distance, the spot
An inactive means that does not act on the image variable means,
From the first distance where the distance to
Within a predetermined range up to a second distance different from the first distance
, The unnecessary spot image variable operation is not performed.
To reduce the distance measurement operation time,
If the value is outside the predetermined range, in other words, from the light receiving means,
If part of the received light spot image deviates,
To prevent the received light spot image from deviating from the means.
The operation for changing the cut image is performed, and the predetermined distance measurement characteristic is maintained.
I am trying.

[0013]

[0014]

FIG. 1 is a block diagram showing a distance measuring apparatus having a configuration which is a premise of the present invention.

The microcomputer 1 issues a control signal to the light projecting circuit 2 and receives a control signal from the distance calculation circuit 3 to convert the control signal into a subject distance. A control signal is issued to the light projecting optical system driving means 4 and the light receiving optical system driving means 5 corresponding to the spot image adjusting means to change the size and blur amount of the light projecting image and the light receiving image.

The light projecting circuit 2 receives a control signal from the microcomputer 1 and projects a signal light having a predetermined light amount and a predetermined wavelength on the subject 7 by the light emitting element 6. The light projecting optical system 8 focuses the signal light from the light emitting element 6. The light projection optical system driving unit 4 changes the focal length of the signal light from the light emitting element 6 by changing the focal length, aperture, etc. of the light projection optical system 8.

The light receiving optical system 9 forms an image of the reflected light from the subject 7 on a light receiving sensor 10 such as a two-part silicon photocell (SPC) or a semiconductor position detecting element (PSD). The distance measurement calculation circuit 3 calculates the output from the light receiving sensor 10 and transmits it to the microcomputer 1 as the subject distance. The light receiving optical system driving unit 5 changes the focal length and the aperture of the light receiving optical system 9 to form an image of the reflected light from the subject 7 at a predetermined distance on the light receiving sensor 10.

FIG. 2A shows the distance measuring device shown in FIG.
FIG. 2A is a diagram illustrating an example of a spot image adjusting unit that changes the size of a spot light of a received light image by controlling a light receiving optical system. In FIG. 2A, the light receiving lens 11 is moved back and forth in the optical axis direction. Thus, the convergence distance at which the reflected light from the subject 7 is imaged on the light receiving sensor 10 is changed. In order to increase the predetermined distance for image formation, the motor 12
To rotate the gear 13 to move the support unit 14 integrated with the light receiving lens 11 to the left. The initial position and the amount of rotation of the motor 12 at this time are detected by a light-receiving lens position detection circuit (not shown).

When a predetermined distance for forming an image is to be reduced, a reverse current is applied to the motor 12 to move the light receiving lens 11 to the right.

FIG. 2B shows a distance measuring device in which the light receiving sensor 10 is moved back and forth in the optical axis direction instead of the light receiving lens 11 so that the reflected light from the subject 7 is imaged on the light receiving sensor 10. FIG. 10 is a diagram illustrating another example of the spot image adjusting unit that changes the focal distance to be changed and changes the size of the spot light of the received light image. In this case, the driving direction of the light receiving sensor 10 to be moved is opposite to that in the example shown in FIG. 2A, and the light receiving sensor 10 is moved to the right when trying to make a predetermined distance for forming an image longer. When approaching, the light receiving sensor 10 is moved to the left.

FIG. 2C shows the distance measuring device shown in FIG.
A fixed stop 15 is inserted between the light receiving lens 11 and the light receiving sensor 10 as a part of the light receiving optical system 9, and the position is moved back and forth so that the aperture diameter is changed in a pseudo manner, thereby blurring the spot light. FIG. 11 is a diagram illustrating another example of the spot image adjusting unit that changes the amount and changes the spot light of the received light image by controlling the light receiving optical system 9. In this case, if the predetermined distance to be imaged is set to the long distance side and the aperture 15 is moved to the left as the subject approaches the short distance side, the aperture diameter is effectively reduced and the blur amount is reduced. . Since the power (light quantity) of the reflected light is larger on the short distance side than on the long distance side, even if the aperture is slightly stopped down, the distance measurement accuracy is not so affected.

FIG. 3 (a) is similar to the example of FIG. 2 (c).
In the distance measuring apparatus shown in FIG. 1, a variable stop 16 is provided between the light receiving lens 11 and the light receiving sensor 10 as a part of the light receiving optical system 9.
Is a view showing another example of the spot image adjusting means for changing the size of the spot light of the received light image by controlling the light receiving optical system 9 in which the blur amount is changed by directly changing the aperture diameter of the stop. It is. Also in this case, the predetermined distance for image formation is set to the far distance side, and the amount of blur is reduced by reducing the aperture of the variable aperture 16 as the subject approaches.

FIG. 3B shows the distance measuring apparatus shown in FIG.
By applying a force evenly in a direction perpendicular to the optical axis of the light receiving lens 11,
By changing the focal length of the light receiving lens 11, the blur amount of the spot image on the light receiving sensor 10 is changed.
FIG. 9 is a diagram illustrating another example of the spot image adjusting unit that changes the size of the spot light of the received image by controlling the light receiving optical system 9. To increase the predetermined distance for image formation, a force is applied in the centrifugal direction of the light receiving lens 11 to smooth the spherical surface and reduce the blur amount of the spot image. Conversely, when trying to shorten the predetermined distance for image formation, a force is applied in the centripetal direction of the light receiving lens 11 to make the spherical surface tight and reduce the blur amount of the spot image.

FIG. 3C is similar to the example of FIG.
In the distance measuring apparatus shown in FIG. 1, the focal length of the light receiving lens 11 is changed so that the amount of blur of the spot image on the light receiving sensor 10 is reduced. FIG. 10 is a diagram showing another example of the spot image adjusting means for changing the focal length, in which a voltage is applied to the light receiving lens 11 to thereby change the refractive index of the light receiving lens 11 to change the focal length.

FIGS. 2 and 3 show an example in which the amount of blur of the received light spot image is reduced. As shown in FIGS. 4 and 5, the light receiving sensor 10 shown in FIGS. By replacing the light receiving lens 11 with the light projecting lens 16, respectively, the spot image adjusting means for changing the size of the spot light of the projected image by controlling the light projecting optical system 8 or the light emitting element 6 in the distance measuring device as it is. Each example can be used.

FIG. 6 is a flowchart illustrating a distance measuring operation in the distance measuring apparatus of FIG. 1 in which the size of the spot light of the received light image is changed by controlling the light receiving optical system 9. Here, the light projecting optical system 8 is fixed, and the reflected light from the subject 7 is imaged on the light receiving sensor 10 by moving the light receiving lens 11 of the light receiving optical system 9 in the optical axis direction shown in FIG. A description will be given of an example having a spot image adjusting unit that reduces the amount of blurring of the spot image by changing the focusing distance to be made.

First, in step 1, whether or not the light-receiving lens 11 is at the initial position is determined by the light-receiving lens position detecting means (not shown). The motor 12 is rotated so as to return to the initial position.

In step 3, the microcomputer 1 instructs the light emitting circuit 2 to start lighting at a predetermined light amount and a predetermined wavelength, and the light emitting element 6 starts emitting light. The projection light is projected onto the subject 7 via the projection optical system 8, and the reflected light is formed into a spot image on the light receiving sensor 10 via the light receiving optical system 9 in step 4.

The light receiving sensor 10 outputs a signal in accordance with the spot position.
The signal is converted into a signal corresponding to the subject distance and transmitted to the microcomputer 1 to perform a distance measurement operation.

In step 6, the initial position of the focused light receiving lens 11 and the position according to the distance measurement data are subtracted, and if the light receiving lens 11 is moved in any direction and how much, the blur amount of the spot image is reduced. Calculate whether it is the minimum.

In step 7, it is determined whether this amount is within the range in which the light receiving lens 11 can be actually moved. If the amount exceeds the maximum movement amount, in step 8, the maximum movement amount is reset. In step 9, the light receiving lens 11 is moved in a predetermined direction by a predetermined amount to reduce the blur amount of the spot image.

In step 10, light emission is started again. In step 11, reflected light from the subject is received.
The distance measurement calculation is performed in step 2 to obtain the distance to the subject 7.

In step 13, this value is determined as a normal object distance, and is stored in a predetermined random access memory area 1a in the microcomputer 1. Then, in step 14, the light receiving lens 11 is returned to the initial position, and a series of distance measuring operations is completed.

FIG. 7 is a diagram showing the relationship between the distance to the subject and the distance measurement data in the example of changing the size of the spot light of the received light image by controlling the light receiving optical system 9 in the distance measuring apparatus of FIG. It is. When the distance of the subject 7 is changed in a conventional distance measuring device that does not consider the blur of the spot image,
Since the spot image rides inside the light receiving sensor 10 between AB in FIG. 7, the linearity is substantially maintained in this range, but when the subject 7 is closer and farther, a part of the spot image is As a result, the center of gravity of the image is shifted (indicated by a dotted line).

However, according to the distance measuring apparatus shown in FIG. 1, since the spot images are sharply formed on the light receiving sensor 10 on both the short distance side and the long distance side, A 'is a physically possible area. The linearity is maintained between -B '(indicated by a solid line).

FIG. 8 shows the operation of one embodiment of the present invention .
This is a flowchart, and the configuration as a distance measuring device is shown in FIG.
Similar to what is shown. In this embodiment, the size of the spot light of the received light image is changed by controlling the light receiving optical system 9 in the distance measuring apparatus of FIG. As shown in FIG. 7, even with a conventional distance measuring apparatus that does not consider blurring of a spot image, the linearity is substantially maintained between A and B.
In order to reduce the shutter release time lag at the time of photographing, in the operation described with reference to the flowchart of FIG. 8, the light receiving lens 11 is moved only when the distance measurement result is closer to the point A and farther than the point B in FIG. When the result of the distance measurement is between points A and B, the light receiving lens 11 is not moved.

First, at step 21, it is determined whether or not the light receiving lens 11 is at the initial position. If not, at step 22, the motor 12 is rotated to return it to the initial position. At step 23, light emission is started. At step 24, light reflected from the subject 7 is received.
In step 5, the distance measurement calculation is performed. If the calculation result is longer than the predetermined distance B (step 26), or if the predetermined distance A
If it is closer (step 27), at step 28
The difference between the distance data and the initial position of the light receiving lens 11 is calculated to calculate in which direction and how much the light receiving lens 11 should be moved. In step 29, it is determined whether or not the moving amount exceeds the movable range. If the moving amount is beyond the movable range, the maximum moving amount is reset in step 30, and the light receiving lens 11 is reset in step 31. Move.

Next, the light is projected again in step 32, the reflected light is received in step 33, the distance is calculated by step 34, and the object distance is obtained. In step 35, the distance is calculated as true distance data. The data is stored in the random access memory area 1a of the computer 1. Then, in step 36, the light receiving lens 11 is returned to the initial position, and the distance measuring operation is completed.

If the result of the first distance measurement in step 25 is shorter than the predetermined distance B and longer than the predetermined distance A (step 27), the spot image does not deviate from the end face of the light receiving sensor 10 and its linearity is maintained. Since there is no problem in the distance measurement accuracy, the distance measurement is not performed again. In step 35, the first distance measurement data is stored in the random access memory area 1a of the microcomputer 1 as true distance measurement data.

The distance measuring operation for reducing the blur amount of the light receiving lens 11 has been described with reference to the flowcharts of FIGS. 6 and 8. In these cases, the light receiving lens 11 is made to emit light and the light receiving sensor 10 is made to emit light. 4 and 5, the size of the spot image projected on the subject 7 is reduced by the same control in the light projecting optical system 8 or the light emitting element 6 as shown in FIG. The same effect can be obtained by the above. Further, by using these together, the spot image to be projected is reduced according to the distance to the subject, and the synergistic effect of reducing the amount of blur on the light receiving sensor 10 provides a synergistic effect on the short distance side and the long distance side of the distance measuring device. The ranging accuracy can be further improved.

[0041]

As described above, according to the present invention, the distance measurement capability and the distance measurement accuracy are improved, and the predetermined distance measurement is possible.
A distance different from the first distance maintained at the distance characteristic.
Useless spot image is possible in a predetermined range up to the second distance
To reduce the distance measurement operation time without performing any operation for changing
It is possible to provide a distance measuring device which can perform the distance measurement.

[Brief description of the drawings]

FIG. 1 is a configuration which is a premise of the present invention ,
1 is a block diagram illustrating a distance measuring device according to an embodiment of the present invention .

FIG. 2 is a diagram illustrating an example of a light-receiving spot image adjusting unit in the distance measuring apparatus of FIG . 1 ;

FIG. 3 is a diagram showing another example of the light receiving spot image adjusting means in the distance measuring device.

FIG. 4 is a diagram showing another example of a light projection spot image adjusting means in the distance measuring device.

FIG. 5 is a diagram showing another example of a light projection spot image adjusting means in the distance measuring device.

FIG. 6 is a flowchart illustrating a distance measuring operation of the embodiment in which the size of a light receiving spot image is changed by controlling a light receiving optical system in the distance measuring apparatus.

FIG. 7 is a diagram showing a relationship between a distance to a subject and distance measurement data in the embodiment in which the size of a light receiving spot image is changed by controlling a light receiving optical system in the distance measuring device.

FIG. 8 shows a distance measuring apparatus according to the present invention, in which the size of a light receiving spot image is changed by controlling a light receiving optical system.
6 is a flowchart illustrating a distance measuring operation according to one embodiment.

FIG. 9 is a diagram showing an example of a conventional active distance measuring device.

FIG. 10 is a diagram showing a spot image on a light receiving sensor of a conventional distance measuring device.

FIG. 11 is a diagram illustrating a relationship between a distance to a subject and distance measurement data of a conventional distance measurement device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microcomputer 2 Light emitting circuit 3 Distance measuring circuit 4 Light emitting optical system driving means 5 Light receiving optical system driving means 6 Light emitting element 7 Subject 8 Light emitting optical system 9 Light receiving optical system 10 Light receiving sensor 11 Light receiving lens 12 Motor 13 Gear 14 Supporting part 15 Fixed aperture 16 Movable aperture 17 Projection lens

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01B 11/00-11/30 102 G01C 3/00-3/32 G02B 7/11

Claims (1)

(57) [Claims] 1. A light projecting means for projecting a light projecting spot image toward an object, and receiving light reflected by the object of the light projecting spot image projected from the light projecting means as a light receiving spot image. A distance measuring device for detecting a distance to an object based on a light receiving signal from the light receiving means, wherein the light projecting means emits a light spot image according to a distance to the object, A spot image varying means for changing the size of at least one of the light receiving spot images received by the light receiving means, and maintaining a distance to the object at a predetermined distance measuring characteristic.
A second distance different from the first distance from the first distance
If the spot image is within a predetermined range until the separation, the spot image
A distance measuring device comprising: an ineffective means that does not act on a variable means .