JPH05322558A - Distance measurement device - Google Patents

Abstract

PURPOSE:To improve distance measuring ability and precision of a short distance side and a long distance side by changing at least either size of a light projection spot image caused by a light projection means and a light receiving spot image caused by a light receiving means in response to a distance up to a object. CONSTITUTION:A microcomputer 1 serves to transmit a first control signal to a light projection circuit 2, in addition, receive a second control signal from a distance measuring operation circuit 3 to convert into a subject distance, transmit a third control signal to a light projection optical system drive means 4 and a light receiving optical system drive means 5 on the basis of the measured data and change the size of a light projection image and a light receiving image and a dim quantity. The drive means 4 serves to change a focus distance, a diaphragm and the like of a light projection optical system 8 and alter a focusing distance of signal light from an emission element 6. In addition, the drive means 5 serves to change another focusing distance and another diaphragm of a light receiving optical system 9 and image-form reflection light from a subject 7 of a specified distance on a light receiving sensor 10. And a light receiving lens of the light receiving optical system 9 is moved in the direction of a light axis in front and rear and the focusing distance for image-forming the reflection light from the subject on the sensor 10 is changed.

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 device suitable for an autofocus camera or the like, which measures the distance to a subject by projecting signal light and receiving the reflected signal light. Related to the improvement of.

[0002]

2. Description of the Related Art In an autofocus camera or the like, a so-called active method is used in which a signal light is projected onto a subject and the signal light reflected by the subject is received to measure the distance to the subject by the principle of triangulation. The range finder of
Widely used from the past.

Further, as disclosed in, for example, Japanese Patent Publication No. 54-39731 and Japanese Patent Laid-Open No. 60-19116, a pair of bisected silicon photocells (SPC) is used as a light receiving means. A range finder capable of measuring a range without a movable part has been widely put into practical use.

FIG. 9 shows a conventional active distance measuring device.
The signal light from the light emitting element 21 is focused by the diaphragm 22 to a predetermined light amount, and then focused by the light projecting lens 23 at the point of the distance L2. When the subject 24 exists at the point L2, the signal light from the light emitting element 21 is
Is reflected by the light receiving lens 25 and the diaphragm 26, and an image is formed at a spot position c on the light receiving sensor 27.

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

The spot position n on the light receiving sensor 27,
The distances to the subject are 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 device constructed as described above. As shown in FIG.
Since the focal length of 5 is sharply formed as the spot image C at the position of the object distance L2, when the object exists at L1 or L3,
As L1 and L3 move away from L2, the light receiving sensor 27
The upper spot image is blurred like N or F and becomes large. At this time, the distance measurement data with respect to the position of the center of gravity of the spot image on the light receiving sensor 27 is originally a straight line such as a dotted line as shown in the figure showing the relationship between the distance to the conventional 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 distance, and linearity is lost as shown by the solid line.

When the focal length of the taking lens extends to the telephoto side, the range finding ability of the range finding device is also required in a wider range, but the necessary range finding accuracy cannot be obtained due to the bending on the long range side. Therefore, the distance measuring ability cannot be satisfied. In addition, the distance measurement accuracy on the short-distance side is also inadequate due to the bend on the short-distance side, and even if you take a picture, it will be a blurred picture, or in order to prevent blurring, the close warning range is set. I had to go far.

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

In this case, however, the light-receiving lens is divided into a main lens section for distance measurement during normal photographing and an auxiliary lens section for macro photography, and the mask has two light-receiving lenses based on the distance measurement distance. Since a method of covering any of the light receiving lenses in the above is adopted, even when the same signal of one light receiving sensor is used, the subject distances are different for normal shooting and macro shooting, so it is necessary to use different shooting lenses. The macro lens had to be inserted, and the structure was complicated and the camera body was large, which was 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 correction must be performed, which impairs mass productivity. Furthermore,
With respect to the light receiving lens at the time of macro photography, the blurring and size of the spot image are not taken into consideration within that range, and similarly, the problem of bending at the short distance side occurs.

An object of the present invention is to solve the above problems and to provide a distance measuring device having a simple structure capable of improving the distance measuring ability and distance measuring accuracy on the short distance side and the long distance side. is there.

[0012]

SUMMARY OF THE INVENTION The present invention is a spot image adjusting means for changing the size of at least one of the light projected spot image by the light projecting means and the light received spot image by the light receiving means according to the distance to the object. Is provided.

[0013]

According to the present invention, depending on the distance to the object calculated by the calculating means in the first distance measuring operation, the projected spot image on the object, the received light spot image on the light receiving element, or both spots. Form an image sharply,
In that state, the distance measurement operation is performed.

[0014]

1 is a block diagram showing a distance measuring device according to an embodiment of the present invention.

The microcomputer 1 outputs a control signal to the light projecting circuit 2 and also receives a control signal from the distance measuring arithmetic circuit 3 to convert it into a subject distance. Based on this distance measuring data, the present invention is realized. 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 onto 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 projecting optical system driving means 4 changes the focal length and the diaphragm of the light projecting optical system 8 to change the focusing distance of the signal light from the light emitting element 6.

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 a subject distance. The light receiving optical system driving means 5 changes the focal length and the diaphragm 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 of FIG.
FIG. 3 is a diagram showing an example of a spot image adjusting unit that changes the size of the spot light of a received image by controlling the light receiving optical system 9. In FIG. 2A, the light receiving lens 11 is moved back and forth in the optical axis direction. Changes the focusing distance at which the reflected light from the subject 7 is imaged on the light receiving sensor 10. When trying to increase the predetermined distance for image formation, the motor 12
Is energized to rotate the gear 13 and move the supporting portion 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 approached, a reverse current is applied to the motor 12 to move the light receiving lens 11 to the right.

In FIG. 2B, in the distance measuring device, the light receiving sensor 10 instead of the light receiving lens 11 is moved back and forth in the optical axis direction so that the reflected light from the subject 7 is imaged on the light receiving sensor 10. It is a figure which shows the other example of the spot image adjustment means which changes the focusing distance made to change, and changes the magnitude | size of the spot light of a 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 the predetermined distance for image formation is to be increased, and When approaching, the light receiving sensor 10 is moved to the left.

FIG. 2C shows the distance measuring device of FIG.
A fixed diaphragm 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 of the fixed diaphragm 15 is moved back and forth to artificially change the diaphragm aperture and blur the spot light. It is a figure which shows the other example of the spot image adjusting means which changes the quantity and which changes the spot light of a received light image by control of the light receiving optical system 9. In this case, if the predetermined distance for forming an image is adjusted to the far side and the diaphragm 15 is moved to the left as the subject approaches the near side, the diaphragm aperture is effectively reduced and the amount of blurring is reduced. .. Since the power (light amount) of the reflected light on the short distance side is larger than that on the long distance side, even if the aperture is slightly narrowed, the distance measuring accuracy is not so affected.

FIG. 3A is similar to the example of FIG. 2C,
In the distance measuring device of FIG. 1, a variable diaphragm 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.
FIG. 6 is a view showing another example of the spot image adjusting means for changing the size of the spot light of the received image by the control of the light receiving optical system 9 in which the amount of blur is changed by directly inserting the aperture and changing the aperture diameter thereof. Is. In this case as well, the predetermined distance at which the image is formed is adjusted to the far side, and the amount of blur is reduced by reducing the aperture diameter of the variable aperture 16 as the subject approaches.

FIG. 3B shows the distance measuring device of FIG.
Applying force uniformly in the 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. 11 is a diagram showing another example of the spot image adjusting means for changing the size of the spot light of the received image by the control of the light receiving optical system 9. When the predetermined distance for forming an image is to be lengthened, a force is applied in the centrifugal direction of the light receiving lens 11 to make the spherical surface gentle and reduce the blur amount of the spot image. On the contrary, when the predetermined distance for forming an image is to be shortened, a force is applied in the centripetal direction of the light receiving lens 11 to tighten the spherical surface and reduce the blur amount of the spot image.

FIG. 3 (c) is similar to the example of FIG. 3 (b),
In the distance measuring device of FIG. 1, the size of the spot light of the received image is controlled by the light receiving optical system 9 in which the focal length of the light receiving lens 11 is changed to reduce the blur amount of the spot image on the light receiving sensor 10. It is a figure which shows the other example of the spot image adjusting means which changes. The voltage is applied to the light receiving lens 11 to change the refractive index of the light receiving lens 11 to change the focal length.

2 and 3 are examples of reducing the blur amount of the received light spot image. As shown in FIGS. 4 and 5, the light receiving sensor 10 in FIGS. By replacing the light receiving lens 11 with the light projecting lens 16, 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. Each can be an example.

FIG. 6 is a flow chart for explaining the distance measuring operation of the embodiment in which the size of the spot light of the received light image is changed by the control of the light receiving optical system 9 in the distance measuring device of FIG. 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 shown in FIG. An embodiment having spot image adjusting means for reducing the blur amount of the spot image by changing the focusing distance is described.

First, in step 1, the light receiving lens position detecting means (not shown) determines whether or not the light receiving lens 11 is in the initial position. If the light receiving lens 11 is not in the initial position, then in step 2, The motor 12 is rotated so as to return to the initial position.

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

The light receiving sensor 10 outputs a signal in accordance with the spot position, and in step 5, the signal is output to the distance measuring calculation circuit 3
Then, the signal is converted into a signal corresponding to the object distance and transmitted to the microcomputer 1 for distance measurement calculation.

In step 6, the initial position of the light-receiving lens 11 that is in focus and the position based on the distance measurement data are subtracted, and by moving the light-receiving lens 11 in either direction, the blur amount of the spot image is reduced. Calculate whether it becomes the minimum.

In step 7, it is judged whether this amount is the amount of movement within the range in which the light receiving lens 11 can be actually moved. If it exceeds the maximum amount of movement, in step 8, it is reset to the maximum amount of movement. 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, and in step 1
The distance measurement calculation is performed in 2 to obtain the distance to the subject 7.

In step 13, this value is determined as the normal subject distance and 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 shows the relationship between the distance to the object and the distance measurement data in the embodiment in which the size of the spot light of the received image is changed by the control of the light receiving optical system 9 in the distance measuring device of FIG. It is a figure. When the distance of the subject 7 is changed in the conventional distance measuring device that does not consider the blurring of the spot image, the spot image rides in the light receiving sensor 10 between AB in FIG. However, when the subject 7 is closer or farther than that, a part of the spot image deviates from the light receiving sensor 10, and the center of gravity of the image shifts (displayed by a dotted line).

However, according to the distance measuring device of FIG. 1, the spot image is sharply formed on the light receiving sensor 10 on both the short distance side and the long distance side, which is a physically possible area A '. Linearity is maintained between -B '(displayed with a solid line).

FIG. 8 is a flow chart for explaining the operation of another embodiment in which the size of the spot light of the received light image is changed by the control of the light receiving optical system 9 in the distance measuring device of FIG. As shown in FIG. 7, even with a conventional distance measuring device that does not consider the blurring of the spot image, the linearity between A and B is maintained, so that the shutter release time lag at the time of shooting can be shortened. Therefore, 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 in FIG. When it is at a point, the light receiving lens 11 is not moved.

First, in step 21, it is judged whether or not the light receiving lens 11 is in the initial position, and if it is not in the initial position, in step 22, the motor 12 is rotated to return it to the initial position, The light emission is started in step 23, the reflected light from the subject 7 is received in step 24, and step 2
Distance calculation is performed at 5. If the calculation result is farther than the predetermined distance B (step 26), or if the predetermined distance A
If it is closer (step 27), in 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 judged whether or not the movement amount exceeds the movable range. If it exceeds the movable range, the maximum movement amount is reset in step 30, and the light receiving lens 11 is set in step 31. To move.

Next, the light is projected again in step 32, the reflected light is received in step 33, the distance to the object is calculated by the distance calculation in step 34, and in step 35, this is used as the true distance measurement data to generate microscopic 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 ends.

If the result of the first distance measurement in step 25 is closer than the predetermined distance B and farther than the predetermined distance A (step 27), the spot image does not deviate from the end face of the light receiving sensor 10 and linearity is maintained. Since there is no problem with the accuracy of distance measurement, re-distance measurement is not performed, and in step 35, the first distance measurement data is stored as it is 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 above with reference to the flow charts of FIGS. 6 and 8. In these cases, the light receiving lens 11 is used as the light projecting lens 16 and the light receiving sensor 10 is used for light emission. By substituting the elements 6, respectively, as shown in FIG. 4 or FIG. 5, the size of the spot image projected on the subject 7 can be reduced by the same control in the projection optical system 8 or the light emitting element 6. The same effect can be obtained with. Furthermore, by using these together, the spot image to be projected is made smaller according to the distance of the subject, and the synergistic effect of reducing the amount of blurring on the light receiving sensor 10 results in a short distance side and a long distance side of the distance measuring device. The ranging accuracy can be further improved.

[0041]

As described above, according to the present invention,
Depending on the distance to the object, change the size of at least one of the projected light spot image and the received light spot image, to reduce the size of the spot image on the far distance side and the short distance side,
Since the amount of blurring of the spot image is reduced, it is possible to improve the distance measuring ability and distance measuring accuracy on the short distance side, and to expand the distance measuring range on the short distance side. Moreover, since it is not necessary to provide a plurality of light-receiving lenses that can be switched as in the conventional case, the structure can be simplified.

[Brief description of drawings]

FIG. 1 is a block diagram showing a distance measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a light-receiving spot image adjusting means in the distance measuring device according to the present invention.

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 the projected spot image adjusting means in the distance measuring device.

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

FIG. 6 is a flow chart showing a distance measuring operation of an embodiment for changing the size of a light receiving spot image 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 an 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. 8 is a flow chart for explaining a distance measuring operation of another embodiment in which the size of the received light spot image is changed by controlling the light receiving optical system in the distance measuring device.

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 showing a relationship between a distance to a subject and distance measurement data of a conventional distance measuring device.

[Explanation of symbols]

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

Claims (1)

[Claims] 1. A light projecting means including a light emitting element, for projecting signal light from the light emitting element toward an object, and a light receiving element, projected from the light projecting means, and reflected by the object. In a distance measuring device comprising a light receiving means for forming an image of the signal light on a light receiving element, and a calculating means for calculating the distance to the object by the light receiving signal from the light receiving element, depending on the distance to the object, A distance measuring device comprising spot image adjusting means for changing the size of at least one of a light projected spot image by the light projecting means and a light receiving spot image by the light receiving means.