JP2682690B2 - Distance measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a distance measuring device, and more specifically, to a multi-point distance measuring autofocus (hereinafter referred to as an autofocus) in a normal camera, a video camera or the like.
AF)) for distance measuring device.

[Prior Art] AF distance measurement methods include a passive method that performs distance measurement according to the brightness distribution information of the subject and projection of light or ultrasonic waves.
There is an active system in which distance measurement is performed by the reflected signal. All of these are distance measurement techniques when the subject is at the center of the screen. However, in recent years, in order to improve the quality of projection technology, distance measurement of multiple points on the screen,
A number of so-called multi-point distance measurement techniques have been proposed, and an AF camera with active multi-point distance measurement by infrared projection that can be realized with a simple configuration has also been commercialized.

For example, a distance measuring device for a camera disclosed in Japanese Patent Application Laid-Open No. 61-246613 has a cross-shaped light projecting unit, detects reflected light from an object with an area sensor, and groups it in the row and column directions. Two-dimensional object distance data is calculated by outputting the types. Further, the distance measuring device disclosed in Japanese Patent Laid-Open No. 62-223734 discloses a plurality of light emitting sources arranged in the horizontal direction of the camera and one one-dimensional position detecting element (wide width) having a predetermined detection width corresponding to the light emitting sources. Type PSD) is placed above or below the light emitting source with a base line spaced apart to perform horizontal multi-point object distance measurement.

Furthermore, the present applicant previously filed Japanese Patent Application No. 63-80297 (Japanese Patent Laid-Open No.
The distance measuring device proposed by
The second light projecting means comprises a light projecting means, a second light projecting means, a photoelectric conversion means formed by a pair of light receiving lenses and a one-dimensional position detecting element (PSD), and a distance measuring calculation means. The means is a multi-point distance measuring device which is formed between two light emitting diodes and one light projecting lens and is arranged between the first light projecting means and the PSD to measure the distance.

[Problems to be Solved by the Invention] Of the above-mentioned conventional active type multi-point distance measuring devices, the principle of triangulation distance measuring using a wide PSD for a light receiving element will be described with reference to FIG. The light projecting lens 101 and the light receiving lens 102 are arranged in the vertical direction of the camera, and the light projecting lens 10
The light from the two infrared light emitting diodes (IRED) 103, 104 arranged in the horizontal direction is projected to the subject 106 via 1, and the reflected light is incident on the PSD 105 via the light receiving lens 102, and the two Distance measurement data is calculated according to the spot position.

However, with this device, the light-receiving area of the PSD, which is the light-receiving element, must be increased in proportion to the number of IREDs (two in the above case), so it is easily affected by the noise component of the stationary light that enters the light-receiving element. , S / N ratio deteriorates.
Therefore, it is possible to divide the PSD according to the number of IREDs, but in that case, there is a drawback that the arithmetic processing circuit becomes complicated.

Further, referring to FIG. 21, another conventional multi-point distance measuring device using the same PSD for one-point distance measuring will be described.
107 and a light receiving lens 108 are provided, and two IREDs 109 and 110 are arranged in parallel with the arrangement direction on the light projecting lens 107 side, and a PSD 111 is arranged on the light receiving lens 108 side. Then, the lights from the IREDs 109 and 110 are reflected by the subject 112 and are incident on the PSD 111. Multi-point distance measurement data is calculated from these two spot positions, but in the case of this device, the same PSD as the conventional one-point distance measurement can be used, so S / N
There is no problem in comparison. However, as shown in FIG. 22, when the subject is at a short distance, the reflected light deviates from the effective range of PSD, which is a problem in the range.

When a plurality of light emitting elements that project light onto the subject are provided, it is conceivable to provide a light projecting lens for each light emitting element. In this case, if the light receiving lens and the light projecting lens are arranged in a straight line with respect to the camera body, a considerable distance is required, which is against the downsizing of the camera.

Therefore, an object of the present invention is to achieve the same wide-range distance measurement at any distance measurement point while ensuring the same accuracy as the conventional one-point distance measurement AF in order to solve the above-mentioned problems. It is to provide a distance measuring device for a multi-point distance measuring AF camera.

Another object of the present invention is to provide a distance measuring device that has a degree of freedom in the arrangement and can downsize the camera even when a plurality of light projecting lenses are provided.

[Means and Actions for Solving the Problem] A distance measuring device according to the present invention includes a first light emitting element that projects light onto a subject through a first light projecting lens, and a subject through a second light projecting lens. The reflected light from the subject is received and received through the second light emitting element that projects light and the light receiving lens that is arranged at a position that is separated from the first and second light projecting lenses by a predetermined distance. A position detecting element for outputting a signal corresponding to the position; and an arithmetic means for calculating a distance for each of the objects in the projection directions of the first and second light emitting elements by using the output of the position detecting element, The light receiving lens is arranged between the first light projecting lens and the second light projecting lens, and
The straight line connecting the first light projecting lens and the light receiving lens and the straight line connecting the second light projecting lens and the light receiving lens form a predetermined angle. Further, the first light emitting element and the second light emitting element emit light in a time division manner, and further, the first or second light emitting element is the first or second light emitting element.
Is arranged at a position away from the optical axis of the light projecting lens. Further, the first or second light emitting element has at least a plurality of light emitting portions, and the first light emitting element and the first light projecting lens sandwich the optical axis of the light receiving lens. The second light emitting element and the second light projecting lens are arranged on the opposite side.

Further, the distance measuring device according to the present invention is such that the first light emitting element that projects light onto the subject through the first light projecting lens and the second light emitting element that projects light onto the subject through the second light projecting lens. And a position at which the reflected light from the subject is received via the light receiving lens arranged at a predetermined distance from the first and second light projecting lenses, and a signal corresponding to the received position is output. A detecting element and a calculating means for calculating a distance to the subject using the output of the position detecting element, and a straight line connecting the first light projecting lens and the light receiving lens and the second light projecting lens. The straight line connecting the light receiving lenses is characterized by an angle of less than 180 degrees, and
The position detecting element defines the opening angle between the two straight lines by α
Then, it is characterized in that they are arranged at an angle of 90 ° -1 / 2 · α.

[Examples] First, before describing the details of the examples of the present invention,
The basic optical arrangement for triangulation according to the present invention and an arithmetic expression for obtaining distance measurement data will be described. FIG. 2 (A) shows a principle diagram of the two-point distance measuring device.
This device is equipped with IRED12 and PSD14 corresponding to the light projecting lens 11 and the light receiving lens 13, respectively. In addition to the conventional general one-point distance measuring system, the optical axis of the light receiving lens 13 is centered. Another set of projection lens 15 and IR in the symmetrical position
It has ED16. Subject 17,18 with this device
The distances l and l'to are respectively expressed by the following equations.

In addition, here, S is a projection lens from the center of the light receiving lens 13.
Distance to the center of 11 or 15 (baseline length), x ₁ and x ₂ are PSD14
The displacements of the spot positions corresponding to the subjects 17 and 18 above from the Oj axis, and f ₂ are the focal lengths of the light receiving lens 13. However
It is assumed that the IREDs 12, 16 and PSD14 are all arranged at the focal positions of the corresponding lenses. Furthermore, the output signals I ₁ , I _{2 of} PSD14
From the above, an arithmetic expression for obtaining the above l ₁ and l ₂ can be obtained as follows. First, regarding the subject 17 side, the ratio of the output signals is I ₁ : I ₂ = (y + x ₁ ): with respect to the spot position x _1.
((T + (y + x ₁ )) holds. From this, the relationship between the spot position x ₁ and the output signals I ₁ , I ₂ is Here, t is the effective length of the light receiving portion of the PSD, and y is the distance from the Oj axis of the PSD to the end of the light receiving portion. Here, y = 1 / 2t is assumed. Substituting equation (3) into equation (1), the subject
The distance l to 17 is Is required. On the other hand, the distance l'to the subject 18 is similarly obtained. That is In this way, one PSD14 can measure distances at two points, and a PSD of the same size as the conventional one-point distance measurement can be used. Furthermore, two sets of light projecting means are symmetrical. Since it is configured, there is also an advantage that both two subjects can be measured in the same distance measuring range.

However, in the device shown in FIG. 2 (A), the light of IRED12, 16 travels in parallel, so the distance measuring points are m ₁ , m in FIG. 2 (B).
_As shown in Fig. 2, almost the same points on the shooting screen are measured in parallel, and the great effect of multi-point distance measurement cannot be expected.

Therefore, as shown in Figure 3, IRED
12 is offset to the left from the projection lens optical axis O _j1 by the distance a in the figure to give an inclination to the projected light, and further, as shown in FIG.
The IRED16 is also offset to the right by the distance a (not shown). With this small amount of offset, the distance measuring points are widened as shown by m ₁ and m ₂ in the image frame of FIG. 5, and a suitable distance measuring zone can be set.

Next, in order to obtain the spot position x ′ ₁ when the offset a is added, first, from FIG. 3, the projection angle φ is Is represented by Here, f ₁ is the focal length of the projection lens 11. For example, if a = 1 mm and f ₁ = 14 mm, then φ≈4 °. Also, from the figure, the object position Z of the object 17 'from the projection lens optical axis is On the other hand, the relational expression between the displacement x ′ ₁ of the spot position on the _{PSD 14} from the optical axis O _j3 and the subject position Z is It is. In addition, a is the optical axis O _j1 , O _j2 of the projection lens 11.
(Second reference figure) than the right direction, likewise x _'1 is a positive value to the right direction from the light receiving lens optical axis O _j3, it shall take the both of the left negative reversed. When the spot position x ′ ₁ is calculated from the above two equations, Becomes Furthermore relation between the output signals I _1, I ₂ of the spot position x ₁ and the PSD is obtained by the equation (3), the x ₁ x '
_By substituting it into ₁ and substituting it, the relationship between the distance 1 to the subject and I ₁ and I ₂ when IRED12 is offset can be obtained. That is, Becomes In the above formula (7) It can be seen from the above equation (1) that the position x ₁ of the spot when IRED12 is not offset is expressed, so rewriting equation (7) Becomes However, in the case of FIG. 3, since the offset is to the left as described above, the value of a <0 is assumed.
By offsetting IRED12 by a from this equation
Also the spot position on PSD14 It shows that it is offset only. And the distance b in FIG. Is equivalent to Regarding the direction of this offset, when considering based on the basic arrangement of FIG. 2, it is better to place the IRED on the outer side of the optical axis of the light projecting lens so that the light receiving spot is particularly effective for a short-distance subject. It is advantageous because it is offset inward on the PSD and does not deviate from the effective light receiving range.
This will be explained with reference to FIG. 4. FIG. 4 (A) shows the arrangement in the above advantageous state, and FIG.
On the contrary, IRED12 is offset inward and the spot is located outside the light receiving range of PSD.

Next, FIG. 6 shows a four-point distance measuring AF camera which employs the distance measuring device of the first embodiment of the present invention having the above-mentioned triangular distance measuring optical arrangement. The camera shown in Fig. 6 has its camera body.
On the upper part of the front surface of 19, the light projecting lenses 2 and 4 are arranged on the left and right with the light receiving lens 5 as the center and are spaced apart by the base line length S. Further, between the light receiving lens 5 and the light projecting lens 2, a viewfinder for preventing parallax is provided. 8 are arranged. A photographing lens 9 is arranged in the center of the front surface of the body 19, and a release button 10 is arranged on one side of the upper surface of the body 19.

The distance measuring apparatus for four-point distance measuring according to the first embodiment of the present invention disposed in the camera body 19 has a first light emitting element (IRED) 1, 1'and a first light emitting element (IRED) 1, 1 ', as shown in FIG. The first light emitting means 12 including the first light projecting lens 2 and the second light emitting element (IR
ED) 3,3 'and a second light emitting means 13 including a second light projecting lens 4, position detecting elements PSD6,6' and a light receiving lens 5
The position detecting means 14 is composed of an AF circuit and a distance measuring calculating means 7 composed of a CPU. IRED 1,1 'or 3,3' are respectively arranged at positions separated by the focal length f _{1 from the} light projecting lenses 2, 4, and PSDs 6, 6'are provided by the light receiving lens 5 at their focal lengths. _They are spaced apart by f ₂ . The light projected from IRED1 and 3 is the subject 1
The light is reflected by 1a and 11b, is condensed by the light receiving lens 5 and is incident on the PSD 6. On the other hand, the projected light from the IREDs 1'and 3'is reflected by the subjects 11a 'and 11b' and is similarly received. 5
It is collected at and is incident on the PSD 6 '. The IREDs 1, 1 ', 3, 3'and PSDs 6, 6'are arranged as shown in FIG. 7 when viewed from the front of the camera.

The operation of the present embodiment configured as described above will be described. First, the subject 11a or 11 by IRED1, 1 '
The distance l to a'is calculated by the calculating means 7 by the above equation (8) using the respective dimensions shown in FIG. However (8)
The formula is for IRED1 and the one for IRED1 'is
It is assumed that I ₁ is replaced with I ′ ₁ and I ₂ is replaced with I ′ ₂ for calculation. Further, the distance to the object 11b or 11'b due to IRED3, 3'can also be calculated by substituting the corresponding variables in the equation (8), but details will be described later.

This embodiment is a four-point distance measuring system as described above, and the distance measuring points on the screen have two-dimensional distance measuring points as shown by m _{1 to} m ₄ in FIG. 7 (B). Is. In many conventional multi-point distance measuring cameras, the distance measuring points are arranged on a straight line, and the relationship between the photographing screen and the distance measuring zone is, for example, as shown in FIG. However, there is a problem that the distance measuring point is located in the background part and the focus is out of focus when shooting in the vertical position as shown in FIG. 8B. In the case of the embodiment, FIG. As shown in (B), even if the image frame is horizontal or vertical, the subject is easily positioned at the distance measuring point, so that the above-mentioned problem does not occur.

In order to determine the arrangement of these four distance measuring points, first, the horizontal direction is determined by the offset amount a of IRED1,1 'or 3,3', and the projection angle is determined by the above equation (6). It is twice the angle. In the above example, since φ = 4 °, the distance measuring points are 8 ° on the left and right. On the other hand, if the distance measuring points in the vertical direction are also set at the same interval as in the horizontal direction, the PSD arrangement interval C (FIG. 7 (A)).
If is determined by the following equation, the measurement points are arranged at the corners of the square in the image frame.

C = 2a PSDs 6 and 6'of this embodiment suppress the stationary light component and
In order to achieve high-accuracy AF with good S / N, it is composed of two detection elements. However, if the value of C is predetermined, PSD6
It is possible to integrate 6 and 6 '.

Further, although the calculation formula of the distance measurement by IRED1,1 'is described by the above formula (8), the distance measurement by the other IRED3 will be described. Should be replaced with. That is, Becomes Therefore, for IRED1, the PSD output And for IRED3 , Respectively, and then the distance 1 is calculated. However, in order to simplify the above calculation of the calculation means 7, in the case of the above formula (9), By replacing, both in case of distance measurement by IRED1 and in case of IRED3 It is possible to obtain the distance l based on the obtained value. More specifically, first, the distance l to be obtained is actually treated as the distance measurement data 1 / l which is the reciprocal of l. Therefore, equations (8) and (9) are used. And the relational expression of 1 / l. In other words, for IRED1, from equation (8) Furthermore, for IRED3, from equation (9) Is required. When these relational expressions are shown as a diagram, they have a linear relationship as shown in FIGS. 10 (A) and 10 (B), respectively. When the IRED1,1 'is made to emit light for distance measurement, the distance measurement data 1 / l is obtained by using FIG. 10 (A) and IRED3,3' in FIG. 10 (B). However, the above IRED
1 ', 3' For the 'output I of' _1, I _'2, respectively PSD6
It is necessary to perform the above processing after replacing with I ₁ and I ₂ .

Next, referring to FIG. 11, the operation of the four-point distance measuring device will be described. The calculating means 7 is composed of an AF circuit 7a and a CPU 7b. In addition, t ₁ , t ′ ₁ , t ₃ and t ′ _{3 in} FIG. 11 are the above IRED1,
1 ', 3,3' are light emitting timing signals for the light emission instruction, also I _1, I ₂ or I _'1, I' ₂ is PSD 6 and PSD 6 '
Is the output signal of. In addition, S ₀ is the instruction for IRED emission selection above, This is a selection signal for selecting the PSD for obtaining.
Also, the AF data was calculated as above. It is. In this constructed distance measuring device as is 'by _3, IRED1～3' light emitting timing signal t ₁ ~t controlled in a time division sequentially emit light, and Is received by the CPU, and the I selected at that time
The characteristic diagram (A) or (B) of FIG. 10 is selected according to the type of RED1 to 3 ', and the distance measurement data 1 / l is calculated.

Next, a distance measuring device according to a second embodiment of the present invention will be described with reference to FIGS. First, in FIG. 12, a light projecting lens 21 is provided on one side of the obliquely upper front of the camera body 22, and at the symmetrical position between the projecting lens 21 and the photographing lens 25 below the obliquely front, the other projecting light is projected. Lenses 22 are provided respectively, and a light receiving lens 23 is provided on the upper left side of the front of the camera body 20. The light receiving lens 23 is located at an intermediate position between the light receiving lens 23 and the light projecting lens 21. A finder 24 is arranged above 25. A release button 26 is provided on the upper surface of the camera body 20. The two light projecting lenses 21 and 22 have a predetermined opening angle α with respect to the light receiving lens 23, and are arranged at a predetermined base line distance. And IRED and PSD are arranged behind each lens. That is, three IRED41s corresponding to the projection lens 21
a, 41b, 41c and 3 IREDs 41d, 4 corresponding to the projection lens 22
1e, 41f, and three PSDs 44a, 44 for the light receiving lens 23
b and 44c are provided. Then, an AF circuit for calculating the distance measurement data based on the outputs of the PSDs 44a to 44c and a calculation means including a CPU are provided.

Next, the arrangement of each element will be described.
As shown in the figure, for the opening angle α of the projection lens arrangement PSD44a set with the following inclination (P direction in the figure)
44c is arranged with the optical axis O _j3 of the light receiving lens 23 as the center, and each optical axis O _{j1 of} the light projecting lenses 21 and 22 arranged at an angle α with respect to the optical axis O _j3 as described above. Offset from O _j2 to the outside in the P direction by a, respectively, IRED 41a to 41c and IR
ED41d to 41f are provided. Further, in the second embodiment, for the sake of simplification of description, it is assumed that the focal lengths of the light projecting lens and the light receiving lens are all the same f, and the above IRED and PSD are all provided at the above focal position. Therefore, in practical use, the value of f may be selected to be optimal for light projection and light reception, and different values may be adopted.

As described above, the distance measuring device of the second embodiment has six two-dimensionally arranged distance measuring points, and the distance measuring point arrangement within the image frame will be described. First, referring to FIG. The light from IRED 41a to 41c is the subject through the projection lens 21.
The light is reflected by 30 distance measuring points, condensed by the light receiving lens 23, and is incident on the PSDs 44a to 44c. The distance measuring points of the image frame at that time are shown by m ₁ , m ₂ , and m ₃ in FIG. Be done. In addition, in FIG. 16 (A), IRED41d-4
The 1f light is reflected by the subject 30, and is similarly incident on the PSDs 44a to 44c. The state of the image frame at that time is m ₄ , m in FIG.
It is indicated by ₅ , m ₆ . Then, FIG. 17 shows the state of projection and reception of the distance measurement, which is a combination of those shown in FIGS. 17th
Each of the points m _{1 to} m ₆ which are distributed with inclination as shown in FIG.

Next, the distance measuring operation of the present embodiment will be described in more detail. First, when it is assumed that reflected light is returned from a distance of ∞ when the object is at a distance of ∞ in FIG.
Light IRED41a~41c to h _1, i _1, j ₁ point on PSD44a～44c, whereas light IRED41d~41f is projected as respectively spot k _1, u _1, v ₁ point on PSD44a～44c . When the subject approaches the camera, the spot moves in the Q or Q'direction in the figure. Therefore, the detection length of the PSDs 44a to 44e can be made equal to the diagonal length, and the measurement length is expanded accordingly. For example, assuming that the PSD has an effective detection width of 1 mm and an effective detection length of 2 mm, the effective diagonal length is 2.24 mm, which means that the measurement length is increased by 1.12 times that of normal use. If the vertical pitch of the PSD is 1.5 mm and the focal length f of the light emitting / receiving lens is 14 mm, the light receiving angle of the PSD with respect to the vertical light receiving lens is 6 °. Therefore, the light projection shown in FIGS. It is necessary to position the IRED so that the angle γ is also set to 6 °.

Next, in the case of this embodiment in which the PSD is arranged with an inclination angle θ And the relational expression of the measured data 1 / l will be described. First, PSD
FIG. 14 shows the spot position of 44b as an example. In FIG. 14 (A), i ₀ , i ₂ and i ₃ indicate the positions of the spots, i ₀ indicates a case where the spot is exactly on the optical axis of the lens, and i ₂ indicates that the subject is farther away and i ₃ is closer to the subject. The spot position in some cases is shown. For example, when the spot is _two points i, when the distance x from the optical axis to the spot PSD44b
The above displacement x'must be converted by the following equation.

x ′ = x cos θ (12) Further, the relationship between the output signal I ₁ and I ₂ ratio of the PSD 44b and the spot position is I ₁ : I ₂ = (y + a + x ′) :( t− (y + a + x ′))
Therefore, substituting equation (12) into this And ask And further calculated from equation (1) Substituting for IRED41b And the relational expression of distance measurement data 1 / l is obtained, Becomes Then, I ₁ and I ₂ in this case are the output currents of the terminals B ₁ and B ₂ of the PSD 44b in FIG. 13, and A ₁ and A ₂ and C ₁ and C in the case of spots by other IRED41a and 41c, respectively. ₂ outputs correspond. On the other hand, in the case of distance measurement by the light emission of the IRED41e, similarly to the above, the spot positions u ₀ , u ₂ , u _{3 in} FIG. 14B are i ₀ , i ₂ ,
Corresponds to i ₃ . Then replace I ₁ and I ₂ in equation (13),
The relational expression of the distance measurement data 1 / l is obtained. That is Becomes Here, I ₁ and I ₂ are the output currents of the terminals B ₁ and B ₂ as in the above, and also in the case of light emission of other IRED41d and 41f,
Similar to the above case, the outputs of A ₁ and A ₂ and C ₁ and C ₂ correspond.

Also in the case of this embodiment, each IRED is selected and emitted in a time division manner. As described above, when the range data 1 / l is obtained, the formula (13) is used by the IRED and the formula (14) is used. Be divided. And in the case of this embodiment, the selected IR
It is assumed that the AF circuit has a function of calculating I ₁ and I ₂ in reverse by ED. That is, the AF circuit is
Selection of RED light emission and switching of the above calculation will also be performed.

Next, six IREDs 41a to 41f and three PSDs 4 according to the present embodiment
A specific example of the AF circuit to which 4a to 44c are connected will be described with reference to FIG. In Figure 18, the photocurrent from PSD44a
I ₁ and I ₂ are respectively converted to voltage signals V ₁ and V ₂ by preamplifiers 52a and 53a, that is, voltages corresponding to the incident light position on PSD 44a, and then supplied to channel changeover switches 54a and 55a, respectively. . The channel changeover switches 54a and 55a are controlled by a channel changeover signal from a channel changeover circuit 60 described later via a changeover circuit 67a.

The other PSD44b and PSD44c are each configured similarly to the above circuit. In FIG. 18, the circuit relating to the PSD 44b is shown with a reference numeral ending in b, and the circuit relating to the PSD 44c is shown with a reference numeral ending in c.

Further, the respective circuits related to the three PSDs 44a, 44b, 44c are selectively switched by the switching signal from the decoder 68 being sent to the switching circuits 67a, 67b, 67c. The decoder 68 sends a driving pulse signal of a constant frequency from the oscillator 65 to the drivers 69a and 69b for selectively causing the six IREDs 41a, 41b, 41c, 41d, 41e and 41f to emit pulses, and In response to the switching command from the CPU, the IRED column switching control is performed on the drivers 69a and 69b, and at the same time, the above-mentioned operation switching signal g of I ₁ and I ₂ is output, and the switching circuits 67a, 67b and 67c are also operated.
The switching control of the three PSD circuits is performed. In other words, the AF sequence at the time of multi-point distance measurement is designed to be performed in a time-division manner in order to perform distance measurement calculation with a common circuit.
Only the output of the PSD44a is processed when the ED41a or 41d emits light, only the output of the PSD44b is processed when the IRED41b or 41e emits light, and only the output of the PSD44c is processed when the IRED41c or 41f emits light. .

Regarding each of the three PSDs 44a, 44b, 44c, one of the voltage signals V ₁ , V ₂ is time-divisionally band-pass filtered (hereinafter referred to as BP) according to the logical level of the channel switching signal.
F). The BPF 56 selectively passes only the frequency components that are the same as the frequency of the drive pulse signal emitted from the oscillator 65, and removes the background light from the photocurrent of each PSD and photoelectrically converts only the effective subject reflected light. Through. The integration switch 57 supplies the filter output of the BPF 56 to the integrator 58 in synchronization with the signal from the integration timing pulse circuit 70. The integrated output V ₁ of the integrator 58 is input to the comparator 59 and compared with the reference voltage 3Vref, and the comparator 59
Is supplied to a channel switching circuit 60 composed of a D-type flip-flop or the like, and a channel switching signal output from the circuit 60 is sent to the switching circuits 67a, 67b, 67c, whereby the PSDs For the two channel changeover switches in the circuit, for example the circuit of PSD 44a, the channel changeover switches 54a, 55a are controlled. The channel switching signal from the channel switching circuit 60 is also supplied to an AND gate circuit 61 for controlling the input pulse of the inverse integration number counter 62 and an integration timing pulse circuit 70. The inverse integration counter 62 also serves as a shift register, the channel switching signal from the channel switching circuit 60 goes to "L" level, the gate circuit 61 opens, and the channel switching switches 54a, 54b, 54c turn on. The counter counts the number of simultaneous integrations during de-integration, and after the AF operation is completed, the AF data is transferred from the built-in shift register to the CPU that performs distance calculation, and the total number of integrations configured by a preset counter etc. The counter 63 counts the total number of simultaneous integrations, that is, the timing pulse from the integration timing pulse circuit 70, and supplies an end signal to the end circuit 64 that ends the AF processing when the set number of times is reached.

The circuit operation of the AF circuit shown in FIG. 18 will be briefly described with reference to the time chart of FIG. AF operation is started when the AF IC receives an AF start signal and a basic clock signal from the CPU. Now, suppose IRED41a, PS
Explaining D44a, when the IRED41a starts pulsed light emission, the photocurrents I ₁ and I ₂ from the PSD 44a receiving the subject light are received.
The ratio of the peak values of the voltage waveforms V ₁ and V ₂ of the output voltages V ₁ and V ₂ of the pre-stage amplifiers 52a and 53a supplied with is equal to I ₁ / I ₂ described above. Also, when the AF start signal is received, the channel switching circuit
60, inverse integration counter 62 and total integration circuit counter 63
Is reset. At this time, since the channel switching signal from the channel switching circuit 60 is "L", the channel switching switch 54a is turned off, the switch 55a is turned on, and the photocurrent
A voltage V ₂ proportional to I ₂ is applied to BPF 56. When the integration timing pulse circuit 70 gives a timing pulse e ₁ to turn on the integration switch 57, the output of the BPF 56 supplies a voltage proportional to the photocurrent I ₂ to the integrator 58. Therefore, the integrated output V ₁ of the integrator 58 is integrated (inverse integrated) at the positive peak b ₁ of the filter output signal of the BPF 56.
When the integrated output V ₁ drops below the reference voltage Vref, the output of the comparator 59 changes from “L” to “H”, and the channel switching signal from the channel switching circuit 60 changes from “L” in synchronization with the timing pulse e _1. since the "H", now the channel changeover switch 54a is turned on, the switch 55a is turned off, voltages V ₁ by the photocurrent I ₁ on behalf of the photocurrent I ₂ is input to the BPF 56. At this time, the integration timing pulse circuit 28 outputs the timing pulse e ₂ that is the frequency of the IRED drive pulse signal delayed by a half cycle compared to when the channel changeover switch 55a is turned on, so the negative peak b of the filter output signal from the BPF 56. Integration (positive integration) is performed at ₂ . In this way, every time the integrated output V ₁ exceeds the reference voltage Vref, signals proportional to the photocurrents I ₁ and I ₂ are integrated in opposite directions in the direction approaching the reference voltage Vref.

Also, when IRED41d is selected, I ₁ and I ₂ are reversed as described above, so the g signal changes due to the switching command from the CPU, and the generation timing of the integration timing pulse is IR.
The reverse of the ED41a case. In IRED41a, although integral in position b ₁ of the positive peak voltage conversion waveform of the current I ₂ has been made, in the case of IRED41d, integral with the negative peak is performed (positive integral) whereas current I ₁ of the voltage waveform Inverse integration is performed at the positive peak of. Further, the gate circuit 61 also counts the integrated pulse when the d signal is "H", and the AF operation is switched.

Now, assuming that the total number of integrations is N ₀ , the relationship between the number of positive integrations N _S and the number of inverse integrations N _G is N ₀ = N _S + N _G (15). The relationship between the number of inverse integration N _G and the total number of integration N ₀ is N ₀ = {I ₁ / (I ₁ + I ₂ )} N ₀ (16).

Therefore, since the total integration number N ₀ counted in the total integration number counter 63 is kept constant by the termination circuit 64, the total integration number N _G is counted in the positive integration number counter 62. Is obtained and the subject l is obtained. Obtained in this way Based on, CPU (13) formula calculates distance measurement data 1 / l.

The present embodiment improves on the fact that a sufficient base line length cannot be obtained due to the camera layout in the first embodiment,
Furthermore, since the moving direction of the spot on the PSD is inclined by a predetermined angle (θ), it has a feature that the distance measuring range can be made longer.

As described above, in the active type multi-point distance measuring device in the AF camera, the light emitting means is provided at the left and right or at the arrangement position of a predetermined opening angle with respect to the light receiving means composed of the one-dimensional PSD to measure the distance (i. ) By using the conventional PSD for one-point distance measurement, it is possible to perform multi-point distance measurement in a wide range while ensuring the same accuracy as in one-point distance measurement.

(Ii) The distance measuring point within the image frame can be set by the placement of IRED.

(Iii) A low-cost multipoint distance measuring device can be realized by using the conventional PSD.

It is possible to provide a distance measuring device for a multi-point distance measuring AF camera having many features such as the following.

Further, as shown in FIGS. 12 and 13, in the second embodiment, the straight line formed by the light projecting lens 21 and the light receiving lens 23 and the straight line formed by the light projecting lens 22 and the light receiving lens 23 are not on a straight line. Since it has a predetermined angle of less than 180 degrees, it increases the degree of freedom when arranging the range finder on the camera body.
Compared to the case where they are arranged in a straight line, they can be arranged in a smaller camera.

[Advantages of the Invention] As described above, according to the distance measuring apparatus of the first aspect of the present invention, the first light emitting element that projects light onto the subject through the first light projecting lens; A second light emitting element for projecting light onto a subject through the light projecting lens, and the first and second
Position detecting element for receiving the reflected light from the subject through the light receiving lenses arranged at respective positions separated by a predetermined distance from the light projecting lens and outputting a signal corresponding to the received position, and the position detecting element. Using the output of the element, the first
And a calculation means for calculating a distance for the subject in the projection direction of the second light emitting element, respectively.
Since the light receiving lens is arranged between the light projecting lens and the second light projecting lens, the same accuracy as that of the conventional one-point distance measuring AF is ensured, and the same wide range is obtained at any distance measuring point. It is possible to provide a range finder capable of measuring a range.

According to the distance measuring device of claim 7, a first light emitting element for projecting light onto a subject through the first light projecting lens;
The second light emitting element that projects light onto the subject through the second light projecting lens, and the light receiving lens that is arranged at a position that is separated from the first and second light projecting lenses by a predetermined distance. A position detecting element that receives the reflected light from and outputs a signal corresponding to the received position; and a calculating means that calculates the distance to the subject using the output of this position detecting element, The straight line connecting the first light projecting lens and the light receiving lens and the straight line connecting the second light projecting lens and the light receiving lens form an angle of less than 180 degrees. It is possible to provide a distance measuring device that has a degree of freedom in arrangement and can downsize a camera.

[Brief description of the drawings]

FIG. 1 is a layout view of each member of the four-point distance measuring device according to the first embodiment of the present invention, and FIG. 2 (A) is a layout of each member when there is no offset in IRED in the multi-point distance measuring device. FIG. 2 (B) is a view showing the distance measuring points of the image frame in the distance measuring device of FIG. 2 (A), and FIG. 3 is a drawing showing the distance measuring device of FIG. 2 (A). Fig. 4 (A) and (B) shows the layout of each member when IRED is offset by the IR in the range finder of Fig. 3.
Fig. 5 is an explanatory diagram showing changes in spot position due to ED +/- offset, Fig. 5 is a display diagram of distance measuring points of an image frame when two IREDs are both offset in a multi-point distance measuring device, and Fig. 6 is , Having the distance measuring device according to the first embodiment of the present invention
A front view of the AF camera, FIG. 7 (A) is a front view showing an arrangement relationship between IRED and PSD of the distance measuring device, and FIG. 7 (B) is a distance measuring point of an image frame of the distance measuring device. 8A and 8B are display diagrams of distance measuring points of a conventional multipoint distance measuring device, and FIGS. 9A and 9B are distance measuring devices of FIG. Fig. 10 (A) and (B) shows the output signal ratio FIG. 11 is a block diagram including a drive unit of the distance measuring device shown in FIG. 1, and FIG. 12 is a schematic diagram showing the relationship between the distance measuring data 1 / l and FIG. Has a point range finder
A front view of the AF camera, FIG. 13 is a layout view of IRED and PSD of the distance measuring device of FIG. 12, and FIGS. 14A and 14B are spot positions on the PSD of the distance measuring device. The diagram shown in FIG. 15, 16 and 17 (A) is a perspective view of the light projecting portion and the light receiving portion of the distance measuring device, and FIGS. 15, 16 and 17 (B) are those in FIG. 15 (A). FIG. 18 is a block diagram of the AF circuit of the AF camera shown in FIG. 12 above, and FIG. 19 is a time chart of the AF circuit shown in FIG. 18 above. 20 and 21 are perspective views of a light emitting unit and a light receiving unit in a conventional AF camera for multi-point distance measurement, and FIG. 22 is a light emitting unit and a light receiving unit of the AF camera in FIG. 21. FIG. 1,1 '... IRED (first light emitting element) 2 ... first light projecting lens 3,3' ... IRED (second light emitting element) 4 ... second light projecting lens 5 ... light receiving lens 6 …… PSD (position detection element) 7 …… Computing means

Claims (8)

(57) [Claims] 1. A first light emitting element that projects light onto a subject through a first light projecting lens, a second light emitting element that projects light onto a subject through a second light projecting lens, and the first light emitting element. And a position detecting element for receiving the reflected light from the subject through a light receiving lens arranged at a predetermined distance from the second light projecting lens and outputting a signal corresponding to the received position. Calculating means for calculating the distance of each of the objects in the projection directions of the first and second light emitting elements using the output of the position detecting element, the first light projecting lens and the second light projecting lens. A distance measuring device in which the light receiving lens is arranged between the light projecting lenses of. 2. The straight line connecting the first light projecting lens and the light receiving lens and the straight line connecting the second light projecting lens and the light receiving lens form a predetermined angle. Ranging device. 3. The distance measuring device according to claim 1, wherein the first light emitting element and the second light emitting element emit light in a time division manner. 4. The measuring device according to claim 1, wherein the first or second light emitting element is arranged at a position apart from the optical axis of the first or second light projecting lens. Distance device. 5. The distance measuring device according to claim 1, wherein the first or the second light emitting element has at least a plurality of light emitting portions. 6. The first light emitting element and the first light projecting lens are opposite to the positions of the second light emitting element and the second light projecting lens with the optical axis of the light receiving lens interposed therebetween. The distance measuring device according to claim 1, wherein the distance measuring device is arranged in 7. A first light emitting element that projects light onto a subject through a first light projecting lens, a second light emitting element that projects light onto a subject through a second light projecting lens, and the first light emitting element. And a position detecting element for receiving the reflected light from the subject through a light receiving lens arranged at a predetermined distance from the second light projecting lens and outputting a signal corresponding to the received position. A calculating means for calculating the distance to the subject using the output of the position detecting element, and a straight line connecting the first light projecting lens and the light receiving lens and the second light projecting lens and the light receiving lens. The distance measuring device characterized in that the straight line connecting the lenses forms an angle of less than 180 degrees. 8. The position detecting element according to claim 7, wherein the position detecting element is arranged at an inclination of 90 ° -1 / 2 · α, where α is an opening angle formed by the two straight lines. Ranging device.