JPS60121408A - Distance measuring device - Google Patents

Abstract

PURPOSE:To measure the distance of an object without placing the object to be focused in the center of a screen, by rotating a light projecting lens and a light receiving lens, whose optical axes are off respective rotation center lines, around rotation center lines synchronously with each other. CONSTITUTION:A light projecting lens 2 and a light receiving lens 4 are shifted from respective rotation center lines by the same quantity and are rotated synchronously with each other while keeping the same shift directions, and the luminous flux from a light emitting element 1 is projected from the light projecting lens 2 to an object in an object field 3, and the reflected light is focused onto a light receiving face of a photodetector 5 by the light receiving lens 4. The object field 3 is scanned in the direction of an arrow to measure the distance successively. Since the incidence position of the refected light on the light receiving face of the photodetector 5 is different by the distance of the object, variation of electric outputs from two output terminals of the photodetector 5 is obtained to measure the distance of the object.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a distance measuring device used in a camera or the like, and particularly in a distance measuring device that projects infrared light or the like toward a subject and detects the distance to the subject based on the reflected light.

Conventionally, with this type of automatic focus detection device that measures and adjusts distance, it has been necessary to orient the camera so that the subject is placed approximately in the center of the screen. Therefore, cameras that are currently commercially available have a built-in mechanism called prefocus to take pictures with a composition that focuses on subjects that are not in the center of the screen.
There is a method in which the camera is first pointed so that the subject is placed approximately in the center of the screen, the focus is adjusted, and then the camera is turned again, the composition is decided, and the photograph is taken. However, (9) this makes the photographing operation cumbersome, and an erroneous operation may result in taking an out-of-focus photograph.

As a solution to this problem, it has been proposed to use a plurality of distance measuring devices to measure distances at many points on the screen, but this method has drawbacks such as high cost.

Therefore, it is an object of the present invention to make it possible to focus while holding the camera in a desired composition without having to place the subject to be focused on in the center of the screen, or without having to change the direction of the camera to match the desired composition. To provide a distance measuring device capable of measuring the distance of a subject to be focused on.

The present invention provides a light projecting optical member that projects a convergent light beam emitted from a distance measuring light source so as to scan a field, and the light projecting optical member is arranged at a predetermined interval, and the light projecting light beam is arranged at a predetermined interval. a light-receiving optical member that receives the reflected light beam from an object inside and outside the object in the same scanning relationship as the axillary projected light beam and converges it on a photoelectric conversion light-receiving element, In a distance measuring device that obtains a distance signal of an object in the field from an incident position, the light emitting optical member and the light receiving optical member have lens optical axes eccentric from their respective rotation centers, and The present invention is characterized in that the light projecting lens and the light receiving lens are rotated synchronously around the respective rotation center lines while maintaining the same direction of eccentricity.

Embodiments of the present invention will be described below with reference to the drawings. First, the concept will be explained with reference to FIG. 1 is a light emitting element such as an infrared light emitting diode that emits distance measuring light such as infrared light;
2 is a light projecting lens that projects the light beam from the light emitting element 1 toward the field of view 3; 4 is the light receiving surface of the light receiving element 5, which receives the reflected light of the projected light beam reflected by an object in the field of view; This is a light receiving lens that focuses the light upward. The light projecting lens 2 and the light receiving lens 4 are provided so as to be rotated in the same direction as shown by arrows in the figure. In each of the lenses 2 and 4, the respective lens optical axes are eccentric with respect to the respective rotation center axes. The amount of eccentricity is the same for both lenses 2 and 4, and both lenses 2 and 4 are rotated synchronously by maintaining the same eccentric direction with respect to the respective rotational center axes.

The light flux from the light-emitting element 1 is projected through the light-emitting lens 2 and strikes an object in the field 3 as a spot, and the reflected light from the object is transmitted to the light-receiving lens 4 and onto the light-receiving surface of the light-receiving element 5. However, the incident position of the reflected light on the light-receiving surface of the light-receiving element 5 varies depending on the distance to the object O, as shown in FIG. Here, the light-receiving element 5 is what is called a semiconductor device detector, and has two output terminals, and the ratio of electrical output from each terminal depends on where on the light-receiving surface the incident light hits. It changes.

Therefore, the object distance can be measured from the output.

Now, the light emitting lens 2 and the light receiving lens 4 are decentered as described above and rotated as described above, and as they rotate, the light emitting and receiving optical paths are covered as shown by the arrows in FIG. The field of view is scanned 3'ft, and various objects existing within the field of view are successively measured. In this embodiment, the photographic lens (5) is focused after the scanning is completed based on the signal indicating the closest distance among the distance measurement results obtained during the scanning.

The above scanning scans the object field in an arc shape. The direction and position of scanning in the field of view can be determined as desired, but in general, considering that the camera is held vertically or horizontally, It is desirable to scan diagonally.

FIG. 3 is a perspective view showing an example of a specific mechanism corresponding to FIG. 1, and in the figure, 1 to 5 are similar to those in FIG.
A release lever is linked to a shutter button (not shown), and is slidably guided by pins 8a+8b installed in an autofocus (AF) unit base 7, and is biased upward in the composition by a spring 9. . Reference numeral 10 denotes a sector gear, which is rotatably supported by a shaft 11 fixed to the AP unit base 7, and has one end formed so as to be engageable with the release lever 6. Reference numeral 12 denotes a two-stage gear, which is rotatably supported by the AF unit base 7 and a gear holder (not shown), the small gear of which meshes with the sector gear 10, and the large gear (6) of the holder 13 of the projection lens 2. It meshes with a gear formed on the outer periphery. The light projecting lens holder 13 is rotatably fitted into the AF unit base 7, and the other part of its outer gear meshes with the rack gear of the connection rack 14. The connecting rack 14 is slidably guided by pins 15a and 15b implanted in the AP unit base 7, and the other part of the rack gear meshes with a gear formed on the outer periphery of the holder 16 of the light receiving lens 4. The light receiving lens holder 16 is rotatably fitted to the i-unit base 7,
It is biased in the clockwise direction in the figure by a spring 17 hooked on a bottle 16m provided on the protruding portion (the outer periphery). Spring 1
7 is to offset the backlash of each gear,
The rotations of the light emitting lens 2 and the light receiving lens 40 are completely synchronized.

To explain the operation of the mechanism shown in FIG. 3, first, when a shutter button (not shown) is slightly pressed, a switch (not shown) is turned ON and power is supplied to a circuit to be described later. When the shutter button is pressed further, the release lever 6 that is linked to it is pushed in against the spring 9, and the bent part of the release lever 6 pushes one end of the sector gear 10, causing the sector gear to move counterclockwise in the figure. The two-stage gear 12 that engages with it rotates clockwise in the figure, and the light projection lens holder 13 rotates counterclockwise in the figure, causing the light projection lens 2 to rotate. As described above, the projected light flux moves in an arc shape. At the same time, the connecting rack 14 moves in the direction A in the figure, and as a result, the light receiving lens holder 16 and eventually the light receiving lens 4 also rotate counterclockwise in the figure, thereby synchronizing with the projected light beam as described above. The received light flux also moves in an arc. In the above stage, while the light-receiving lens is rotating, distance measurement of various objects in the object is performed continuously as described above, and the signal corresponding to the closest distance is detected among the distance measurement signals obtained during the scanning. This is used as a lens control signal, and when the shutter button is pressed, a switch (not shown) moves the photographic lens based on the lens control signal to focus on the nearest object, and then completes the exposure operation. let

In FIG. 3, the eccentricity of the optical axis of each lens 2, 4 with respect to the rotation center of each lens 2.4 and the eccentric direction with respect to each rotation axis are made the same so that both lenses are rotated completely synchronously. It goes without saying that the mechanism shown in the figure is constructed.

Each eccentric lens 2, 4 can be easily made by plastic molding.

In Figure 3, gears were used to synchronize the rotation of the light emitting and receiving lenses, but if the rotation angle of the lenses is small,
The rotation of both lenses is achieved by providing pins similar to those shown in Fig. 16a on the outer peripheries of the holders 13 and 16 for the light emitting and receiving lenses, and connecting them with levers having two holes that fit into these pins. It is also possible to synchronize.

It is quite difficult to scan the emitted and received light beam diagonally across the field without problems such as complicating the mechanism, space required, accuracy, etc., but as shown in Figures 1 and 3. According to the configuration described in , this can be easily achieved.

Next, an example of an electric circuit used in an embodiment of the present invention will be explained with reference to FIG. During the first stroke (9) of the shutter button of the camera, the main switch 102 of the camera is closed, the light emitting lens and light receiving lens start scanning as described above, and power is supplied from the power supply battery 101 to each circuit. A positive power supply Vae is supplied from a power supply filter circuit constituted by capacitors 103 and 105 and choke coil 104). Further, the reference voltage generation circuit 106 outputs a reference voltage KVC that does not depend on temperature, and the continuous pulse generation circuit 107 outputs a reference voltage KVC of 10 k.
A clock signal of about Hz is generated.

Resistance 192. The time constant of the time constant circuit composed of a capacitor 193 and a buffer 194 is set to a time corresponding to 0 from the start to the end of scanning of the light emitting lens and the light receiving lens.Therefore, after the main switch 102 is closed, Since the output of the buffer 194 is at a low level for a while, a clock signal is output from the OR gate 195, and the switching transistor 197 is turned on and off accordingly. Accordingly, the drive transistor 189 is turned on and off, and the infrared light emitting diode (hereinafter referred to as I RED and (10
) 1 for short, a constant current flows through it due to the action of the OP amplifier 186 and the feedback resistor 191, and the blinking operation is repeated.

1 Semiconductor device detector (hereinafter referred to as PSD) which received the reflected light from RKD1 50 outputs A and B are PS
An output is displayed depending on the position of the incident light on D5. Both output currents are connected to the OP amplifier 109 (130) and the resistor, which constitute the next-stage active bypass filter, respectively.
Capacitor network 110-113 (131
~134), and only the 10 kHz signal is intensively amplified. Its output is further fed to the OP amplifier i which constitutes the next stage non-inverting amplification preamp
4 (135) and resistance 115 to 117 (136 to 1
38) is further expanded. This amplified signal is transmitted to the analog switch 118 (139
), and the amplified AC signal is sent to the capacitor 12.
0 (141), and the integration circuits 119 and 120 (140, 141
) is slightly smoothed out. These two outputs are connected via an OP amplifier 121 (142) constituting a buffer amplifier to an adder circuit composed of an OP amplifier 143 and resistors 144 to 147, an OP amplifier 148, and a resistor 1.
49 to 151 are input to a subtraction circuit configured as υ.

The output of the OP amplifier 143 of the adder circuit is input to an inverting circuit composed of an OP amplifier 180 and resistors 181 and 182, where it is inverted and amplified, and then passed through a resistor 184 and a capacitor 185 that provide a slight delay time. Said IRED
1 drive OP amplifier 186. Therefore, when the output of the OP amplifier 143 of the adder circuit increases, the output of the OP amplifier 180 of the inverting circuit decreases, the output of the OP amplifier 186 also decreases, and the output of 1RED1 decreases.

Furthermore, when the output of the OP amplifier 143 of the adder circuit decreases, the output of υ1RFJD1 increases by the opposite operation. Due to this operation, during the scanning operation of the light emitting lens and the light receiving lens, the output of IREDI is feedback controlled so that the output of the adder circuit is always constant regardless of the object distance or the reflectance of the object. be done. Note that the delay circuit 18
Reference numeral 4,185 is for preventing oscillation, and its time constant is set so short that it can be ignored compared to the scanning time of the light projecting lens and the light receiving lens.

Output of OP amplifier 143 of adder circuit (VA + VB)
is constant as described above, the OP amplifier 1 of the subtraction circuit
The output of 48 (■mu vB) changes depending on the distance.

In this embodiment, the optical system and PSD are arranged so that the closer the object distance is, the higher the output of the subtraction circuit becomes.

The output of the OP amplifier 148 of the subtraction circuit, which is object distance information, changes depending on the change in object distance due to scanning in the field, but its peak output is output from the OP amplifier 152 of the next stage, NPN.
) is strongly held by a peak detection circuit configured with a transistor 153 and a capacitor 154. The output corresponding to the closest object is capacitor 1.
It will be held at 54. The retained peak analog signal is converted into a 3-bit binary code by a converter 155 at the next stage.

When the scanning operation of the light projecting lens and the light receiving lens is completed (13), the time constants of the time setting circuits 192 and 193 elapse and the output of the buffer 194 is inverted to a high level. Therefore, the output of the OR gate 195 is also inverted to a high level, the switching transistor 197 is turned on, the IREDI drive transistor 189 is turned off, and the IREDI is turned off. Also, the output of the buffer 194 is connected to the AND gate 1
56 to 158, so AND gates 156 to 1
The output of the converter 155 appears from the output of 58, and its binary output is sent to the next stage decoder/driver 159.
The signal is converted into a decimal code, and among the LED (light emitting diode) arrays 161 to 167, the LED corresponding to the distance measurement signal lights up to display the distance.

Furthermore, the output t of the converter 155 is used as a signal for controlling the driving of the photographic lens, and is used in a digital feedback servo mechanism, for example, to generate a pulse in conjunction with the movement of the photographic lens and compare it with a count value of the pulse. By controlling the position of the photographic lens, the closest object in the field can be photographed in focus.

(14) In the above embodiment, a semiconductor device sensor (PSD) was used as the light-receiving element 5, but instead, a photodiode or the like having a plurality of light-receiving parts used in conventional distance measuring devices may be used. Good too. In this case, although the processing circuit is somewhat complicated, it repeatedly obtains a digital distance measurement signal while scanning the subject, and the circuit holds the signal at the nearest distance (for example, -carrier/A conversion). (This can be done using the same processing as in this embodiment).

Furthermore, in the above embodiment, distance measurement and focusing are performed so as to give priority to the closest object in the scanned object field, but this can be achieved by appropriately changing the circuit configuration of the processing calculation. A person skilled in the art can easily give priority to a long-distance subject or to a medium-distance subject.

According to the present invention, the desired composition can be achieved without having to place the subject to be focused on in the center of the screen, or without having to reorient the camera to achieve the desired composition after placing the subject in the center of the screen. It is possible to measure the distance to the subject to be focused on while holding the camera, and this can be accomplished using a relatively simple and compact mechanism.

Furthermore, since the direction of scanning can be easily made diagonal to the screen, the camera can function effectively regardless of whether it is held horizontally or vertically.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of an embodiment of the present invention, Fig. 2 is a diagram showing its distance measurement principle, Fig. 3 is a torso view showing the specific mechanism of the range measurement system of the embodiment, and Fig. 4 is a diagram showing the distance measurement principle of the embodiment. FIG. 4 is an electrical circuit diagram that can be used in the embodiment described above. DESCRIPTION OF SYMBOLS 1... Light emitting element, 2... Light emitting lens, 3... Field of view, 4... Light receiving lens, 5... Light receiving element, 6
...Release lever 17...AF unit stand, 13...Emitting lens holder, 14...Connection rack, 16...Light receiving lens holder,

Claims (1)

[Scope of Claims] 1. A light projecting optical member that converges and projects the luminous flux emitted from the distance measuring light source so as to scan the object field, and the light projecting optical member is arranged at a predetermined interval, and a light-receiving optical member that receives a reflected light beam of the projected light beam by an object within the subject valve in the same scanning relationship as the projected light beam and converges it onto a photoelectric conversion light-receiving element; In a distance measuring device that obtains a distance signal of an object in a subject valve from the incident position of reflected light, the light emitting optical member and the light receiving optical member are:
A light projecting lens and a light receiving lens whose optical axes are eccentric from their respective rotation center lines, and which are rotated synchronously around the respective rotation center lines while maintaining the same direction of eccentricity. A distance measuring device characterized by: 2. The distance measuring device according to claim 1, wherein the light projecting lens and the light receiving lens are rotated in a rotation range that is an arc (1) so that scanning of light projecting and receiving light obliquely crosses the field of view. 3. Claims 1 or 2 include an operation mechanism for focusing the photographing lens on the object in response to distance information corresponding to the nearest or farthest object among the distance signals obtained above. distance measuring device.