JPS6315525B2 - - Google Patents

Description

[Detailed description of the invention]

FIELD OF THE INVENTION The present invention relates to a range finder, particularly a projection light range finder using the principle of triangulation, which is equipped with a logic circuit for appropriately processing signals from a photometer circuit for distance measurement. . BACKGROUND ART Conventionally, a method is provided that includes a light beam projection means and a plurality of light receiving elements arranged so as to receive the light projected from the light beam projection means and reflected from the distance measurement target, and which light receiving element receives the light. 2. Description of the Related Art A distance measuring device has been proposed which detects the position of a distance measuring object in each predetermined zone by detecting the distance with a photometric circuit corresponding to a light receiving element. To explain the principle of this type of conventional device in more detail using FIG.
a to 1d are light receiving elements for distance measurement; 10 is a light emitting element for pulsed light projection which is a light beam projection means; L1, L
2 is a lens. Now, for example, when the pulsed light from the light-emitting element 10 is reflected by the object to be measured and detected by the light-receiving element 1a, the object to be measured is in zone A (as shown in Table 1), and when the object is in the zone A (as shown in Table 1), the object is in the zone When the light receiving element 1c is used, the light receiving element is placed in zone E (see Table 1), and when the light receiving element 1d is used, the light receiving element is placed in zone G (see Table 1). In addition, two light receiving elements 1a and 1
When ab is detected, the light receiving element 1b is placed in zone B (in Table 1) between zones A and C.
and 1c, there is an object to be measured in zone D (Table 1), and when the received light signals 1c and 1d, there is an object to be measured in zone F (Table 1), and furthermore, the pulsed light reflected by any light receiving element is If not detected, it means that the object to be measured is in zone H (in Table 1) at infinity. Furthermore, when the three light receiving elements 1a, 1b, and 1c detect pulsed light reflected due to variations in the mounting of the light receiving elements 1a to 1d and the light emitting element 11, the light receiving element 1b and the light emitting element 11 are detected in zone C corresponding to the light receiving element 1b. (Table 1), similarly, light receiving elements 1b, 1c, 1d
When detected, it means that there is an object to be measured in zone E (as shown in Table 1). This situation is shown in Table 1.
That is, in Table 1, for the combination of signals of "1" in which each of the light receiving elements 1a to 1d detects pulsed light, only the value for the zone where there is an object to be measured is shown as "1", and the zone where there is no object is shown as "0". be.

[Table] Incidentally, problems that are unavoidable when using such a conventional device will be explained with reference to FIGS. 2 and 3. In FIG. 2, when a light beam is projected onto a position α of the object to be measured, a part of the reflected light from this part is incident on the light receiving element 1d, while a part of the reflected light from the part α is incident on the light receiving element 1d. is incident on the part β, and the β
When a part of the reflected light is incident on the light receiving element 1b, the output of the light receiving elements 1a to 1d becomes "0101", which does not correspond to the normal signal shown in Table 1.
A signal indicating that there are objects to be ranged at two locations in zones C and G is output. Further, as shown in FIG. 3, if there are objects to be measured at the positions of zones C and G within the range of the projection beam, the reflected light from the γ and δ portions will be transmitted to the light receiving element 1b, respectively. 1d, the outputs of the light receiving elements 1a to 1d are "0101" as in Fig. 2.
Therefore, a signal that does not correspond to the normal signals shown in Table 1 is output. Table 2 lists such signals that do not correspond to normal signals.

[Table] Purpose of the Invention The present invention has been made to deal with the problems that occur in such conventional devices. A logic circuit is provided that outputs a signal of a zone corresponding to the most frequently used focal position (ordinary focal point) of the lens. That is,
A distance measuring device according to the present invention includes a light beam projecting means and a plurality of light receiving elements arranged so as to receive light projected from the light beam projecting means and reflected from a distance measuring object, and which light receiving element In a distance measuring device that detects the position of a distance measurement target in each predetermined zone by detecting whether light has been received by a photometry circuit corresponding to a light receiving element, one, two, or three photometry circuits are used. According to the light reception signal of each corresponding light receiving element from first to third discrimination means for generating a signal indicating the zone position; and a fourth discriminating means for generating a signal indicating the infinite zone position when the received light signal is not outputted from any of the photometric circuits.
and a fifth determining means that generates a signal indicating the zone position corresponding to the common focus of the photographic lens when a received light signal that cannot be determined by the first to fourth determining means is output. This is a newly created distance measuring device characterized by the provision of a logic circuit. Therefore, according to the device of the present invention, when an abnormal signal is output, a signal for the normal focal position is output, and the photographing lens position can be controlled to the normal focal position, thereby preventing out-of-focus photography. This effect can be obtained by reducing the probability that this will occur. Embodiments Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings. FIG. 4 is a system diagram of an automatic focusing device for lenses to which the present invention is applied.
is a light-receiving element whose one end is connected to a constant potential Vr, and 2
3a to 2d are photometering circuits for detecting pulse input whose specific configuration is shown in FIG. It's a flip-flop. SW ₁ is a button that can be pressed down manually (not shown)
When this button is pressed down, the photographing lens (not shown) starts moving from a position closer than the closest position capable of photographing toward an infinity position. SW ₂ is a switch that closes when the photographic lens moves to a predetermined position closer than the closest position that can be photographed, and switch 6 outputs a "high" signal after a certain period of time from the closing of switch SW ₁ . In the delay circuit, this certain period of time is the time required for the ranging circuit, mainly the photometry circuits 2a to 2d, to become stable after the power is turned on. AN ₀ is an AND circuit, and when the AND circuit AN ₀ rises, the one-shot circuits 7 and 9 each output a pulse with a fixed time width. This time width is set so that the pulse of the one-shot circuit 9 is shorter than the pulse of the one-shot circuit 7. Reference numeral 8 denotes a drive circuit for the light emitting element 10, which causes the light emitting element 10 to emit pulsed light in response to a pulse from the one shot circuit 7. 4 is _a logic circuit whose concrete example is shown in _FIG . is D flip-flop 3a~3d
It becomes "high" based on the output a~ of. FF is an RS flip prop, and the above switch
It is reset by closing SW ₁ , and set by the falling edge of the one-shot circuit 9 pulse. This RS flip
The Q output of the flop FF is connected to the control terminal of the output control circuit 5, and is further connected to the AND circuit _AN4 .
~ Connected to one input terminal of AN ₁₆ . A movable contact piece 13 slides on the fixed electrode 11 and the comb-shaped electrodes 12A to 12G in synchronization with the movement of the photographing lens. As the movable contact piece 13 moves, a clock is output from the inverter IN ₂ , and this clock is input to the counter decoder 14, which outputs a clock from the terminal A' as the lens moves. ~G′ becomes “high” in sequence
I'm getting used to it. Mg is a magnet having a permanent magnet as its core, and when this magnet Mg is electrically conductive, the movement of the photographing lens is locked by a locking lever or the like linked thereto, as is well known in the art. A stopper is provided so that the photographic lens stops moving at its final position, and when the photographic lens stops moving due to this stopper, it means that the focus has been adjusted to infinity. 5 is an output control circuit, which is composed of nine 2-input AND circuits, and one input of these AND circuits is
Connected to the Q terminal of the RS flip-flop FF,
The other input is connected to the output terminals A to H of the logic circuit 4 and the output IR of the OR circuit OR ₀ , respectively, and the output of each AND circuit is connected to a light emitting diode L ₁ to
L ₉ is connected. Therefore, terminal A is “high”
If B is “high” then L _{1 is} IR
If is “high”, _L9 will light respectively. Note that FIG. 5 shows the photometry circuits 2a to 2d in FIG.
A circuit specifically showing one of the above, 1 is a light receiving element,
IC ₁ is a constant current source for biasing transistors BT ₈ , BT ₁₀ , BT ₁₂ , BT ₁₈ , C ₂ is a delay capacitor,
IC ₂ is a constant current source for creating a constant voltage, and RV is a variable resistor for adjusting the inversion level of the comparator AC. The operation of this circuit is such that while the light receiving element 1 is receiving only steady light, the transistors BT ₄ , BT ₀ ,
Feedback is applied through the feedback path via BT ₂ , BT ₆ , BT ₁₄ , and BT ₁₆ , and the base potentials of transistors BT ₁₄ and BT ₁₆ are equal, and the output of comparator AC is V ₀
is "low". In addition, even if the external light changes slowly, if the capacitance of capacitor C ₂ is made small, sufficient feedback will be applied to the transistor.
The base potentials of BT ₁₄ and BT ₁₆ are equal, and the output of comparator AC will never be inverted to “high”.
Furthermore, even if external light changes relatively quickly or feedback is not applied immediately, feedback is applied before the balance of the circuit is significantly lost. If you keep it in mind, the output of the comparator AC
V ₀ never flips to “high”. However, when the light-receiving element 1 receives pulsed light that changes rapidly, the capacitor C ₂ does not provide feedback that can cope with this sudden change, and the balance of the circuit is greatly disrupted, causing the output of the comparator AC to become V ₀ is inverted to “high”. This signal becomes the pulse detected signal. Further, FIG. 6 is a specific circuit example of the logic circuit 4 of FIG. 4. Based on Table 1, a logical formula showing the relationship between the terminals A to H of the logic circuit 4 and the inputs a to is as follows. A=a... B=a・b・・ C=・b...+a・b・c・ D=・b・c・ E=・・c・+・b・c・d F=・・c・d G=...d H=... Also, when the signals shown in Table 2 are input,
Since it is not normal, set the IR′ terminal to “high”. Here, IR' is IR' = IR ₁ + IR ₂ + IR ₃ + IR ₄ = (ab)... d + a, b, d, and an example of a circuit that satisfies this logical formula is shown in Figure 6. A detailed explanation thereof will be omitted.
Furthermore, an example of a circuit that satisfies IR=IR′+IR ₅ +IR ₆ =IR′+a...c is the AND circuit AN ₂ shown in FIG.
The OR circuit is shown as OR ₀ . Next, the operation of FIG. 4 will be explained. When switch SW ₁ is closed, power supply to the ranging circuit starts, and the photographing lens (not shown) moves from a position even closer than the closest position where photography can be performed to an infinity position. RS flip flop FF
is reset and the delay circuit 6 starts counting the delay time. At this time, the movable electrode 13 is the fixed electrode 1
I haven't reached 1 or 12. When sufficient time has elapsed for the photometry circuits 2a to 2d to stabilize, a "high" signal is output from the delay circuit 6, and when the photographic lens reaches a predetermined position closer than the nearest position where photography can be performed, The switch _SW2 is closed, and the output of the AND circuit _AN0 becomes "high", and the one-shot circuits 7 and 9 each output a pulse with a fixed time width. The light emitting element 10 is activated by the signal from the one shot circuit 7.
emits pulse light, and the pulse from the one shot circuit 9 falls while the light emitting element 10 is emitting light. Light emitting element 1
The outputs from the photometric circuits 2a to 2d corresponding to the light receiving elements 1a to 1d that received the reflected light from the one-shot circuit 9 are taken into the D input of the D flip-flop and outputted at the falling edge of the pulse from the one shot circuit 9.
This signal will be stored from now on. Furthermore, the RS flip-flop FF is set at the falling edge of the pulse from the one-shot circuit 9.
The Q output terminal becomes “high” and the AND circuit
AN ₄ to _{AN 16} become operational, and the output control circuit 5 operates to control the light emitting diodes L ₁ to L ₉ based on the output terminals A to H of the logic circuit 4 or the output IR signal of the OR circuit OR ₀ . The zone where one of them lights up and the distance is measured is from the closest position A to the infinitely far position H
A display is displayed indicating that either of these conditions exists or that distance measurement is not possible. Note that when no light reception signal is output from any of the photometric circuits mentioned above, the light emitting diode _L8 corresponding to the infinite zone position H is lit. When the photographing lens reaches the closest position where photographing is possible, the movable contact piece 13 begins to move on the fixed electrodes 11 and 12. For example, when the E terminal of the logic circuit 4 is set to "high", when the photographing lens moves to a position corresponding to zone E, the movable contact piece 13 connects the comb-shaped fixed electrode 12 and the rectangular fixed electrode 11 five times. Short-circuited, the inverting circuit IN ₂ outputs five pulses, and the output terminal E' of the counter decoder 14 becomes "high".
When , the output of AND circuit AN ₁₂ becomes “high”
As a result, the output of the OR circuit _OR4 becomes "high". As a result, the transistor BT becomes conductive, the charge in the capacitor _C1 is discharged through the coil of the magnet Mg, and the movement of the photographic lens is stopped, so that the focal position becomes the zone E. Furthermore, when the output IR of the OR circuit OR ₀ is "high", that is, when the signals of the D flip-flops 3a to 3d are not normal, the output of the OR circuit OR ₂ is
G'' becomes "high". Therefore, when the photographing lens reaches zone G, the output G' of the counter decoder 14 becomes "high", and the outputs of the AND circuit AN ₁₆ and the OR circuit OR ₄ become "high". ” and the magnet
Mg becomes conductive and the movement of the lens is stopped. Therefore, at this time, the most frequently used zone G
The lens position is determined at (normal focal position). In other words, when an indistinguishable light reception signal is emitted,
A signal is generated indicating the zone position corresponding to the common focus of the photographic lens. As described in detail in the above embodiments, the present invention includes a light beam projection means and a plurality of light receiving elements arranged so as to receive the light projected from the light beam projection means and reflected from the distance measurement target. , a distance measuring device configured to detect the position of a distance measurement target for each predetermined zone by detecting which light receiving element receives light with a photometric circuit corresponding to the light receiving element,
The normal zone position corresponding to the light receiving element is determined by the light reception signals of one, two, or three photometric circuits of the corresponding light receiving element, or,
It includes first to third discrimination means that generate a signal indicating an intermediate zone position between two regular zones or a regular zone position corresponding to the central light receiving element, and further includes a first to third discrimination means that generates a signal indicating an intermediate zone position between two regular zones, or a regular zone position corresponding to the central light receiving element, a fourth discriminating means that generates a signal indicating the zone position at infinity when no signal is output from the lens, and a fourth discriminating means that generates a signal indicating the zone position at infinity; a logic circuit having a fifth determination means for generating a signal indicating a zone position corresponding to the zone position;
With a simple configuration, in this type of distance measuring device, even when the abnormal signals listed in Table 2 above are generated, signals of the respective focal positions are outputted, so that out-of-focus photography is not performed. This is of great practical value and will further expand the applications of this type of distance measuring device.

[Brief explanation of the drawing]

Figure 1 is a diagram explaining the principle of the conventional device, Figure 2 is a diagram explaining the principle of the conventional device.
3 and 3 are diagrams explaining the problems of the conventional device, FIG. 4 is a system diagram of an automatic focus adjustment device to which the present invention is applied, FIG. 5 is a specific example of the photometry circuit shown in FIG. 4, and FIG. The figure shows a specific example of the logic circuit shown in FIG. 1a to 1d... Light receiving element, 2a to 2d... Photometric circuit, 10... Light beam projection means, 3a to 3d...
...D flip-flop, 4, AN ₂ , OR ₀ , OR ₂
...Logic circuit.

Claims (1)

[Scope of Claims] 1. A light beam projecting means, and a plurality of light receiving elements arranged so as to receive light projected from the light beam projecting means and reflected from a distance measurement target, and which light receiving element is selected. In a distance measuring device that detects the position of a distance measurement target in each predetermined zone by detecting whether light has been received by a photometric circuit corresponding to the photodetecting element, and a first discrimination means that generates a signal indicating the normal zone position corresponding to the light receiving element, and the light receiving signals of the two light receiving elements from the two photometric circuits,
a second discrimination means that generates a signal indicating an intermediate zone position between the two regular zones corresponding to each of the light receiving elements, and when light reception signals from the three adjacent light receiving elements are output from the three photometric circuits; , a third determining means for generating a signal indicating the normal zone position corresponding to the central light receiving element, and a fourth determining means generating a signal indicating the infinite zone position when the light receiving element is not outputted from any of the above photometric circuits. and a fifth discriminator that generates a signal indicating the zone position corresponding to the common focus of the photographing lens when a received light signal that cannot be discriminated by the first to fourth discriminators is output.
1. A distance measuring device comprising: a logic circuit having a determining means.