JPH10281761A - Distance-measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a distance-measuring apparatus by which a highly accurate measurement with small temperature dependence can be realized by improving the mounting structure of a photoelectric conversion device (a CCD or the like). SOLUTION: Regarding a mounting structure onto a CCD light guide tube 16, an aluminum board 17 on which IC packages 21R, 21L for CCD's 20R, 20L as independent components are mounted and a flexible printed-wiring board 11, on its rear, to which tips of lead terminals 21a, at the IC packages 21R, 21L are fixed and bonded by solder pieces 22 are piled up. The lead terminals 21a at the IC packages 21R, 21L are inserted into slit-shaped lead-terminal through holes 17a which are formed in the board 17, and center limited regions on the rear of the IC packages 21R, 21L are bonded to the board 17 by a thermosetting adhesive 18. When a temperature change is generated, local regions in the center limited regions become immobile parts with reference to the board 17, remaining peripheral regions are freely expanded substantially, and the optical-axis interval B0 between the IC packages 21R, 21L is decided in proportion to the coefficient of thermal expansion of a blank (i.e., aluminum) for the substrate 17, i.e., the light guide tube 16, and to the temperature change.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external light triangular distance measuring device which can be used in a vehicle rear-end collision prevention device and the like, and more particularly to a mounting structure of a photoelectric conversion device in the distance measuring device.

[0002]

2. Description of the Related Art Conventionally, a principle configuration of a triangular external light (stereo method) distance measuring device mounted on, for example, an autofocus camera or the like, as shown in FIG. It comprises a compound-eye imaging optical system including a pair of left and right imaging lenses (positive lenses) 1 _R and 1 _L for producing binocular parallax, and a photoelectric conversion / electric system. This photoelectric conversion / electrical system is arranged on a substantially focal plane of the imaging lenses 1 _R and 1 _L to form a space 1 of the imaging.
Photosensor arrays 2 _R and 2 _L such as CCDs as photoelectric conversion elements for converting a three-dimensional illuminance distribution into an electric signal sequence, and output signals for each cell (segment) of the photo sensor arrays 2 _R and 2 _L are sequentially quantized. It has quantization circuits 3 _R and 3 _L and a logic unit 4 for performing a required logical operation process based on a pair of left and right imaging data strings of the collected digital values to calculate a distance signal.

A pair of left and right image forming lenses 1 _R and 1 _L have an optical axis S
_R and _SL are parallel to each other, have the same focal length _{fe, and} are arranged on the same plane to form a binocular imaging optical system. The subject T is separated by a reference length (optical axis interval or interpupillary distance) B. focused by a pair of left and right imaging lenses 1 _R, 1 _L, object image each of the photosensor array 2 _R, on 2 _L corresponding to focal plane inverted real (illuminance distribution) is tied. When the distance d to the subject T is finite, the principle of triangulation (similar to a triangle)
Is given by the following equation:

D = B · _fe / (X ₁ + X ₂ ) = B · _fe / X (1) where X ₁ and X ₂ are the image point positions on the photosensor arrays 2 _R and 2 _L and the subject offset distance between the image point position at which T is at infinity, X is the sum of X ₁ and X _2, a relative shift amount of the object image (phase difference).

Accordingly, the distance d to the subject T can be determined by detecting the spatial phase difference X. As can be seen from equation (1), the greater the optical axis interval B and the longer the focal length _fe , the higher the distance measurement accuracy.

Conventionally, a distance measuring device is unitized or modularized in order to facilitate mounting on a completed product such as a camera manufactured by a user. For example, a distance measuring unit shown in FIG. 7 is known. Have been. This distance measuring unit is for mounting a photographic camera, and includes a plastic two-lens plate (lens module) 1 integrally provided with imaging lenses 1 _R and 1 _L , and a pair of left and right windows 6 _R and 6 _{R. L} , and guides the incident light rays from the imaging lenses 1 _R and 1 _L to form a focal length f _e.
A light guide tube (lens holder) 6 made of a box-shaped aluminum for securing the length of the lens barrel, and photosensor arrays 2 _R and 2 _L having a light receiving surface on the bottom surface of the light guide tube 6 on which an image-forming light beam is projected. ing.

[0007] 2 with respect to the mounting structure of the light guide tube 6 of the eye lens plate, integrally have a projecting portion 8 _R, 8 _L in binocular lens plate 1 is left and right ends of the image forming lens 1 _R, 1 _L Each of the overhang portions 8 _R and 8 _L has an insertion groove (mortise groove) 9.
Are formed, and projections (mortises) 10 are formed upright at the left and right ends of the upper surface of the light guide tube 6. And 2
In the assembling work of the eye lens plate 1 and the light guide tube 6, after inserting the protrusion 10 into the insertion groove 9 to join three pieces,
An adhesive is injected into the gap between the fitting surfaces to fix the two.

[0008] With respect to the structure for mounting the light guide tube 6 of the photosensor array, as illustrated in FIG. 8, was equipped with an IC package (ceramic package or the like) 5 _R, 5 _L of the photosensor array 2 _R, 2 _L of independent parts and aluminum substrate 7, the IC package 5 _R on the back surface, 5 the tip of the _L of the lead terminals 5a has a flexible print circuit board 11 which is fixed is overlapped with solder 22, the four corners of the substrate 7 photoconductive tube 6 It is screwed to the back of. IC package 5 _R, 5 _L of the lead terminals 5a are inserted into the slit-shaped lead terminal through holes 7a formed on the substrate 7, I
C Package 5 _R, 5 _L of the back of the thermosetting adhesive 12a
To the entire surface of the substrate 7. Then, the IC package 5 _R, 5 _L backside short side lead terminals 5a are not overhang are adhered together by an ultraviolet curable adhesive 12b for temporary fixing.

In such an external light triangulation type distance measuring device, as described above, Bf
It is sufficient to increase the value of _e. However, when the focal length _fe is increased, the F number of the lens increases, and the lens becomes darker, so that the image plane illuminance decreases. Therefore, it is desirable to use a lens having a short focal length _fe and increase the image plane illuminance.
Moreover, when the focal length _fe is shortened, the length of the lens barrel of the light guide tube 6 can be shortened, which is convenient for realizing a thin distance measuring device. On the other hand, the distance B between the optical axes is increased by an amount corresponding to the reduction of the focal length _fe , so that the distance measurement accuracy is not deteriorated. For this reason, for a device requiring high-precision distance measurement, such as a distance measurement device employed in a vehicle rear-end collision prevention device, for example,
There is a demand for a thin distance measuring device having a focal length _fe of about 2 cm and an optical axis interval B of about 6 cm.

[0010]

However, the above distance measuring device has the following problems.

In the mounting structure of the photosensor array, when the material of the substrate 7 and the material of the light guide tube 6 are the same (for example, aluminum), assuming that the coefficient of linear expansion is β, the temperature Δt is higher than the temperature at the time of assembly. When a change occurs, the optical axis interval is given by the following equation.

B ₀ (1 + β · Δt) (2) where B ₀ is the optical axis interval at the temperature at the time of assembly.

Since the IC packages 5 _R and 5 _L thermally expand at the same time as the substrate 7 thermally expands due to a temperature change, the actual amount of change in the optical axis interval is determined by the amount of expansion / contraction B ₀ β · Δt of the substrate 7.
The expansion and contraction amounts of the packages 5 _R and 5 _L are superimposed. However, since the back surfaces of the IC packages 5 _R and 5 _L are entirely adhered to the substrate 7 with the thermosetting adhesive 12 a, the thermal stress unevenly distributed on the IC packages 5 _R and 5 _L due to the difference in the degree of adhesion of the adhesion surfaces. Has occurred. Therefore, it is difficult to quantitatively evaluate the thermal expansion of the IC packages 5 _R and 5 themselves, and the thermal expansions of the left and right independent IC packages 5 _R and 5 _L are different. Therefore, even if the optical axis interval is B ₀ at the temperature at the time of assembly, when the temperature change of Δt occurs, the optical axis interval is no longer given by the above equation (2).

Therefore, it is not possible to perform temperature compensation by disposing a temperature sensor.

On the other hand, in the lens mounting structure,
Since the eye lens plate 1 is a plastic lens, it is inexpensive, unlike a glass material, but has the disadvantage of large thermal expansion. And the wider the optical axis interval B, the more
The amount of expansion and contraction of thermal expansion becomes apparent.

For example, as shown in FIG. 8A, at the temperature at which the projections 10 of the light guide tube 6 are inserted and fixed in the insertion grooves 9 on both sides of the two-lens lens plate 1, the optical axis interval B is B _0. When the temperature rises by Δt, if the linear expansion coefficient of the plastic of the two-lens lens plate 1 is α and the free-lens expansion of the two-lens lens plate 1 is assumed, the optical axis interval B _t Is given by B ₀ (1 + α · Δt). However, since the twin-lens plate 1 is sandwiched and restrained between the projections 10 of the aluminum light guide tube 6 having a smaller linear expansion coefficient, the thermal compression force indicated by the arrow in FIG. Since the linear expansion coefficient of aluminum is β (<α) since it is added to the eye lens plate 1, the actual optical axis distance B
_t is simply given by the following inequality and cannot be uniquely identified.

B ₀ (1 + β · Δt) <B _t <B ₀ (1 + α · Δt) (3) As described above, the optical axis interval naturally expands and contracts due to thermal expansion due to temperature change Δt. As shown in equation (3),
The temperature dependence of the amount of expansion and contraction cannot be determined clearly and unambiguously due to the complexity of apportionment of mechanical restraint and differences in Young's modulus, and the optical axis spacing at a certain temperature becomes indefinite within an ambiguous range (error). ing. For this reason, even if an attempt is made to attempt to compensate the temperature of the optical axis interval by arranging a temperature sensor in the vicinity of the two-lens lens plate 1, the principle error given by the equation (3) is introduced. I can't compensate. In particular, the principle error B ₀ (α−β) Δt increases linearly as the temperature becomes lower or higher, and therefore, in an environment of severe temperature change, such as a distance measuring device used in an automobile rear-end collision prevention device. In a distance measuring apparatus that requires high accuracy, it is impossible to combine a plastic lens with a light guide tube made of metal such as aluminum.

The light guide tube 6 is also made of plastic and may be approximated to α ≒ β. However, this means that the linear expansion coefficient of the light guide tube 6 is increased. Therefore, the light guide tube 6 and the photosensor array 2 _R , Since the influence of the thermal stress in the mounting structure with 2 _L is increased, it directly affects the measurement accuracy of the phase difference X. Therefore, the realization of high-precision measurement with little temperature dependence and the plasticization of the imaging lenses 1 _R and 1 _L conflicted with each other.

In view of the above problems, the first aspect of the present invention
An object of the present invention is to provide a distance measuring device capable of realizing high-precision measurement with little temperature dependency by improving the mounting structure of the photoelectric conversion device.

A second object of the present invention is to realize a high-precision measurement with little temperature dependency and to improve the structure of the imaging lens and its mounting structure, thereby reducing the cost of the imaging lens by using a plastic lens. It is an object of the present invention to provide a distance measuring device capable of realizing integration.

[0021]

Means for Solving the Problems In order to solve the first problem, a first means adopted by the present invention is that a fixed portion of a pair of photoelectric conversion devices is spot-fixed at the same position with respect to a substrate. It is in. That is, according to the present invention, the first imaging lens and the second imaging lens, which are independent components having the same optical axis and are parallel to each other, are mounted on the lens receiving surface of the light guide tube, and are used for distance measurement. A pair of imaging optics that create parallax between the imaging and
A first photoelectric conversion device that converts the illuminance distribution of the image formed by the first imaging lens into an electric signal sequence, and a second photoelectric conversion that converts the illuminance distribution of the image formed by the second imaging lens into an electric signal sequence In a distance measuring device in which a substrate on which the device is mounted is fixed to a back surface mounting surface of the light guide tube, the surface of the substrate is located at a local area at the same position on a line including an optical axis interval on the back surfaces of the two conversion devices. And a spot fixed.

As described above, in the mounting structure of the photoelectric conversion device, the local region at the same position on the back surface of both photoelectric conversion devices is spot-fixed to the substrate. Since the substrate follows the thermal expansion of the substrate, the local region becomes an immovable portion with respect to the substrate, but the region other than the local region is substantially free from expansion because it is not constrained. For this reason, the thermal expansion of the photoelectric conversion device is offset, and the optical axis interval between the two photoelectric conversion devices is only affected by the thermal expansion of the substrate. That is, the optical axis interval between the two photoelectric conversion devices is determined in proportion to the coefficient of thermal expansion of the substrate and a change in temperature. Therefore, by providing the temperature sensor, it is possible to perform temperature compensation of the optical axis interval between the two photoelectric conversion devices, and it is possible to perform high-accuracy distance measurement independent of a temperature change.

It is desirable that the local region is a portion corresponding to the origin of the light receiving surface, that is, a center-limited region centered on the optical axis.

In particular, in the case where a concave portion for limiting the amount of fixation is formed on the substrate surface, the amount of fixation of the adhesive can be reliably limited, so that the degree of fixation of both photoelectric conversion devices can be equalized.
The offset can be enhanced.

In order to solve the second problem, a second means adopted by the present invention is to use a pair of imaging lenses of the same independent parts, and to connect both imaging lenses to the lens receiving surface of the light guide tube. It is characterized in that it is mounted with a flexible structure that has a small restraining force and is thermally expandable in the same direction on a line including the optical axis interval.
That is, it is characterized in that it is fixed to the lens receiving surface at a base point portion offset by the same distance on the same side on a line including the optical axis interval with respect to the optical axis in the respective peripheral regions of both imaging lenses. I do.

Due to the temperature change, each point of any of the imaging lenses causes a minute displacement due to thermal expansion with respect to the lens receiving surface with the base portion as a fixed point, but the fixed portion of the imaging lens is at the optical axis with respect to the optical axis. Since the base portions are offset by the same distance on the same side on the line including the interval, the axis of any of the imaging lenses is displaced by the same distance in the same direction and the same distance on the line including the optical axis interval. Therefore, even if the imaging lens itself thermally expands, the optical axis interval does not change based on the thermal expansion. However, since the lens receiving surface, which is the base body on which the imaging lens is mounted, also undergoes thermal expansion, the base portion of the imaging lens is displaced following the thermal expansion of the lens receiving surface. Although the interval changes, the optical axis interval is uniquely determined in proportion to the thermal expansion coefficient and the temperature change of the lens receiving surface, that is, the material of the light guide tube.
High accuracy ranging can be realized by improving the temperature characteristics. As described above, since the temperature dependency of the optical axis interval is independent of the thermal expansion of the imaging lens, a plastic lens having a large thermal expansion coefficient can be used, and cost reduction can be realized.

[0027]

Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a plan view showing a distance measuring apparatus according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line AA 'in FIG. 3 (A) is a plan view showing an imaging lens used in the distance measuring apparatus, FIG. 3 (B) is a bottom view showing the imaging lens, and FIG. 3 (C) is C in FIG. 3 (A).
FIG. 4 is a cross-sectional view showing a state cut along the -C 'line.
4A is a plan view showing a leaf spring retainer used in the distance measuring apparatus, FIG. 4B is a side view showing the leaf spring retainer, and FIG.
FIG. 5C is a sectional view taken along the line CC 'in FIG. 4A, and FIG. 5A is a partial plan view showing a CCD mounting substrate used in the distance measuring device. FIG. 5 (B) shows the same CC
A partial plan view showing a state where the CCD is mounted on the D mounting board,
FIG. 5C is a sectional view taken along the line CC in FIG. 5B.

The mounting structure of the imaging lens 50 _R (50 _L ) constituting the pair of left and right imaging optical systems of this embodiment is a lens receiving portion 16 of an aluminum die-cast box light guide tube 16.
It fits the window 16 _R (16 _L ) of a. Optical axis S
_An imaging lens 50 _R (50 _L ) is provided in which _R (S _L ) is arranged in parallel and left and right independent components are equal.

On the back (back) side of the light guide tube 16,
An aluminum substrate 17 having a CCD 20 _R (20 _L ) for converting a spatial illuminance distribution of the image formed by the imaging lens 50 _R (50 _L ) into a time-series data signal is mounted by screws. For the mounting structure of the CCD light guide tube 16, as shown in FIG. 5, CCD 20 independent component _R (2
0 _L ) Dual in-line type IC package 21 _R
An aluminum substrate 17 on which (21 _L ) is mounted and a flexible printed wiring board 11 to which the ends of lead terminals 21 a of an IC package 21 _R (21 _L ) are fixed by solder 22 are laminated on the back surface. IC package 21 _R
The (21 _L ) lead terminal 21 a is inserted into a slit-shaped lead terminal through hole 17 a formed in the substrate 17, and only the center-limited region on the back surface of the IC package 21 _R (21 _L ) is thermosetting adhesive. It is adhered to the substrate 7 with the agent 18. Mounting hole 1 for screwing to light guide tube 16 in substrate 17
7b is formed. Also, a recessed portion 17 for limiting an adhesive margin is provided inside the slit-shaped lead terminal through holes 17a, 17a.
c and 17c are formed to regulate the bonding margin of the thermosetting adhesive 18 so as not to spread. Further, the two lead-side terminals 21a of the IC package _21R ( _21L ) where the lead terminals 21a do not protrude are bonded with an ultraviolet curing adhesive 19 for temporary fixing. Then, between the substrate 17 and the flexible printed wiring board 11, the double-sided release paper is peeled off and the adhesive pad 40 is attached with an adhesive layer which is exposed.
Is sandwiched. Lead terminals 21a of the IC package 21 _R (21 _L) is Tsukinui this with adhesive pad 40.

On the other hand, the imaging lens 50 _R (50 _L ) of the present embodiment.
Is a substantially plano-convex single lens as shown in FIG.
Spherical or aspheric lens curved surface portion 51 and its peripheral flange portion 52
Are plastic lenses such as PPS integrally molded. On the back surface of the peripheral flange portion 52 of the imaging lens 50 _R (50 _L ), a base cylindrical projection 53a standing at the center of the crescent-shaped fixing step 53 and standing up and down near the projection 53a. The auxiliary columnar projections 53b, 53b are integrally formed. The center of the base column projection 53a is offset from the axis O by a distance E. On a line (X-axis) connecting the axis O and the base columnar projection 53a, an alignment notch 54 is formed on the side opposite to the base columnar projection 53a. Peripheral flange 52 of the imaging lens 50 _R (50 _L )
On the surface of, the indenter receiving protrusions 55a, 5a are formed at three vertices of an isosceles triangle (including an equilateral triangle) in which the position just above the base cylindrical protrusion 53a is a vertex, and the X-axis passing therethrough is perpendicular to the base.
5b and 55c are integrally formed. The top surfaces of the indenter receiving projections 55a, 55b, 55c are formed as convex curved surfaces. Then, the peripheral flange portion 5 of the imaging lens 50 _R (50 _L )
On the back surface of the slider 2, floating spherical projections 56 b, 56 c for sliding substitution are integrally formed directly below the indenter receiving projections 55 b, 55 c. In addition, the small projection 57 floating on the Y axis is also provided.
a and 57b are integrally formed.

In the imaging lens 50 _R (50 _L ) of the left and right independent parts having such a shape, the base cylindrical protrusion 55 a is fitted into the stop hole 16 b of the lens receiving portion 16 a, and the base cylindrical protrusion 5 is formed.
An adhesive is applied to and fixed to the fixing substitute step 53 around the periphery 5a. Before the adhesive is applied, the alignment lens is applied to the edge notch 54 so that the imaging lens 50 _R (5
0 _L ) is rotated about the base cylindrical protrusion 55a as the center of rotation to perform optical axis alignment.

As shown in FIG. 1, the base cylindrical projection 55a of each of the imaging lenses 50 _R (50 _L ) has an optical axis interval B _0.
Are offset to the same side by an offset distance E on the line (X-axis) including.

The imaging lens 50 having a one-end fixed structure according to this embodiment.
_R (50 _L ) has the peripheral flange 52 elastically pressed down from above by a leaf spring retainer 60, and prevents the edge notch 54 from rising from the lens receiving portion 16 a. As shown in FIG. 4, the leaf spring retainer 60 of this embodiment has a circular aperture opening 6.
1a, a ring-shaped aperture stop plate 61, and the stop plate 61
Bent leg pieces 6 projecting integrally in opposition to each other in the diametrical direction
2 and 63, and light-shielding skirts 64 and 65 covering the edges of the imaging lens formed by the flange forming press. The ring-shaped aperture stop plate 61 has indenters 66a, 66b, 66 formed as bulges by press molding at the vertices of an isosceles triangle corresponding to the indenter receiving projections 55a, 55b, 55c of the lens.
c. The distal ends of the bent leg pieces 62 and 63 are bifurcated, and as shown in FIG. 1, a washer 71 is fitted between the two forks and the bent leg pieces 62 and 63 are screwed to the lens receiving plate 16a with screws 72. . Ring-shaped aperture stop plate 61
Opening deformation suppressing ribs 77 and 78 bulged by press molding are formed at connecting portions with the bent leg pieces 62 and 63.

As described above, in the CCD mounting structure, since the center-limited region on the back surface of the IC package 21 _R (21 _L ) is bonded (spot-fixed) to the substrate 7 with the thermosetting adhesive 18, the temperature is reduced. When a change occurs, the center limited area on the back surface of the IC package 21 _R (21 _L ) is
In order to follow the expansion and contraction of the substrate 17, the local region of the center limited region becomes an immovable portion with respect to the substrate 17. Then, the peripheral region on the back surface of the IC package 21 _R (21 _L ) is substantially free from expansion since it is not restrained. Therefore, IC
Package 21 _R (21 _L) the optical axis interval B _t between the substrate 1
7 is only affected by the thermal expansion. The optical axis interval B
_t is determined in proportion to the thermal expansion coefficient β of the substrate 17, that is, the material (aluminum) of the light guide tube 16, and the temperature change t.
That, IC package 21 _R (21 _L) the optical axis interval B _t between is given by the temperature change. B _t = B ₀ (1 + βΔt) (4) Therefore, by disposing the temperature sensor, the optical axis interval B
Temperature compensation of _t can be performed, and high-precision distance measurement independent of temperature change can be performed.

In particular, the recesses 17c, 17c for limiting the fixing allowance
Is formed, and the amount of fixation of the adhesive can be reliably limited, so that the degree of fixation on the left and right can be equalized.

Further, in this embodiment, the adhesive-coated pad 40 is interposed between the substrate 17 and the flexible printed wiring board 11, and the bottom of the lead terminal through hole 17a is closed. Dust or the like does not enter the gap between the flexible printed wiring board 11 and short circuit failure between lead terminals or between printed wiring on the flexible printed wiring board 11 can be prevented.

Further, since the adhesive pad 40 supports the flexible printed wiring board 11 by surface contact, an excessive stress is hardly applied to a fixing portion between the lead 21a and the solder 22, thereby preventing a connection failure and the like. it can.

On the other hand, both the imaging lens 50 _R (50 _L ) and the lens receiving portion 16a undergo thermal expansion due to a temperature change. Each point of the imaging lens 50 _R (50 _L ) is defined by using the base cylindrical projection 55a as an anchor (anchor) point and a lens receiving portion 16a.
Causes thermal expansion displacement, but the imaging lens 50 _R (5
0 _L ) is a position offset by the same distance E to the same side on the line (X-axis) including the optical axis interval _Bt with respect to the optical axis S _R (S _L ). the axis O is a line including the optical axis interval B _t of the imaging lens 50 _R (50 _L) (X
On the axis) in the same direction and the same distance. Therefore, even when the imaging lens 50 _R (50 _L) itself is thermally expanded, the change in the optical axis interval B _t based thereon does not occur. The effect of the thermal expansion is only received from the lens receiving portion 16a, which is the base on which the imaging lens _50R ( _50L ) is attached. That is,
Optical axis distance B _t is proportional to the coefficient of thermal expansion β and the temperature change Δt of the lens receiving portion 16a i.e. the optical tube 16 material (aluminum) so determined uniquely. That is, the optical axis spacing B _t between lenses is given by equation (4).

Therefore, by providing a temperature sensor between the imaging lenses 50 _R (50 _L ) on the lens receiving portion 16a and measuring the temperature, temperature compensation without a principle error becomes possible, and the temperature characteristics are improved. High precision ranging can be realized. Thus, the temperature dependence of the optical axis interval B _t is to become independent of the thermal expansion of the imaging lens itself 50 _R (50 _L), allows the use of large plastic lenses of thermal expansion,
Cost reduction can be realized.

In particular, in this embodiment, since the auxiliary columnar projections 53b, 53b are fixedly anchored to the stopper holes 16b of the lens receiving portion 16a with the auxiliary columnar projections 53b, 53b interposed therebetween in addition to the base columnar projection 53a. As a matter of course, the character of the base columnar projection 53a as a fixed point becomes stronger, and the thermal expansion of the lens _50R ( _50L ) itself can be restricted in the X-axis direction.

Further, since the floating spherical projections 56b and 56c and the small floating projections 57a and 57b have a small contact area with the lens receiving portion 16a and are in a point contact state, the heat of the lens _50R ( _50L ) itself is reduced. The frictional resistance at the time of expansion is reduced, the lubricity is increased, and the expansion becomes almost free. It is to be noted that a material in which a lubricant is coated on the lens receiving portion 16a can be employed.

Although the leaf spring retainer 60 of this embodiment is a three-point leaf spring retainer, the indenter receiving projections 55a, 55b and 55c are provided.
Has a convex curved surface and is in point contact, so that when the lens 5 is displaced by thermal expansion, frictional resistance can be reduced as much as possible. Further, since the leaf spring retainer 60 is also used as an aperture stop, the number of components is reduced, and cost reduction can be achieved.

When the leaf spring retainer 60 is tightened with the screw 72 and screwed to the lens receiving plate 16a, the indenters 66a, 66
When the b and 66c are pressed against the indenter receiving protrusions 55a, 55b and 55c, the bent leg pieces 62 and 63 are bent, so that the round aperture 61a may be distorted. However, in this example,
Since the opening deformation suppressing ribs 67 and 78 are formed between the edge of the aperture opening 61a and the roots of the bent leg pieces 62 and 63, and the flexural rigidity is enhanced, distortion spreads to the edge of the aperture opening 61a. Therefore, the deformation of the aperture 61a is suppressed.

Further, since the plate spring retainer 60 has a light shielding skirt 64 and 65 around the edges of the ring-shaped aperture stop plate 61, an imaging lens 50 edge of _R (50 _L) (thickness side)
50 _R (50 _L ) without forming black ink
Even if it is assembled, stray light incident from the edge can be eliminated. A high-performance ranging device can be provided at low cost.

Since the bending rigidity of the leaf spring retainer 60 is increased by the light shielding skirts 64 and 65, the deformation of the aperture 61a is suppressed.

[0047]

As described above, the present invention is characterized in that the fixing portions of a pair of photoelectric conversion devices are spot-fixed at the same position with respect to the substrate. Play.

(1) The thermal expansion of the pair of photoelectric conversion devices is offset, and the optical axis interval between the pair of photoelectric conversion devices is only affected by the thermal expansion of the substrate. Is determined in proportion to the coefficient of thermal expansion of the substrate and the temperature change. Therefore, by providing the temperature sensor, it is possible to perform temperature compensation of the optical axis interval between the two photoelectric conversion devices, and it is possible to perform high-accuracy distance measurement independent of a temperature change.

(2) In the case where a concave portion for limiting the fixing allowance is formed on the substrate surface, the fixing allowance of the adhesive can be reliably limited, so that the degree of fixation of both photoelectric conversion devices can be equalized, and the offsetting effect can be obtained. Can be increased.

(3) In addition to the above configuration, the present invention provides
Using a pair of imaging lenses of the same independent parts, both imaging lenses were attached to the lens receiving surface of the light guide tube with a flexible structure that has little restraining force in the same direction on the line including the optical axis interval and can thermally expand. It is characterized by: Since the optical axis interval is uniquely determined in proportion to only the coefficient of thermal expansion of the material of the lens receiving surface and the temperature change, temperature compensation of the optical axis interval becomes possible, and high precision ranging can be realized by improving the temperature characteristics. Then, a plastic lens having a large coefficient of thermal expansion can be used, and cost reduction can be realized.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along the line AA 'in FIG.

3A is a plan view showing an imaging lens used in the distance measuring device, FIG. 3B is a bottom view showing the imaging lens, and FIG. 3C is a line CC ′ in FIG. 3A. It is a cutting arrow view showing the state where it cut along the line.

4A is a plan view showing a leaf spring retainer used in the distance measuring apparatus, FIG. 4B is a side view showing the leaf spring retainer,
FIG. 4C is a sectional view taken along the line CC ′ in FIG. 4A.

5A is a partial plan view showing a CCD mounting substrate used in the distance measuring apparatus, FIG. 5B is a partial plan view showing a state where a CCD is mounted on the CCD mounting substrate, and FIG. FIG. 6B is a sectional view taken along the line CC in B).

FIG. 6 is a block diagram showing a schematic configuration of an external light triangulation type distance measuring device.

FIG. 7 is an exploded perspective view showing a conventional ranging unit for mounting a photographic camera.

8A is a longitudinal sectional view showing a state where a CCD is mounted on a CCD mounting substrate in the distance measuring unit, and FIG. 8B is a partial plan view thereof.

9A is a plan view showing a thermal expansion relationship between a light guide tube and a two-lens lens plate in the distance measuring unit, and FIG. 9B is a bottom view showing a state where a CCD mounting substrate is screwed to the light guide tube. FIG.

[Explanation of symbols]

11 ... Firekishiburu printed wiring board 16 ... box-type optical guide tube 16 _R (16 _L) ... window 16a ... lens receiving portion 16b ... locking hole 17 ... aluminum substrate 17a ... lead terminal through holes 17b ... mounting hole 17c ... adhesion margins Limited Concavity for use 18 Thermosetting adhesive 19 UV curing adhesive 20 _R , 20 _L CCD 21 _R , 21 _L IC package 22 Solder 40 Pad with adhesive 50 _R , 50 _L Imaging lens 51 ... Lens curved surface portion 52... Peripheral flange portion 53... Sticking substitute matching step portion 53 a… Base columnar projection 53 b… Auxiliary columnar projection 54… Alignment edge notched portion 55 a, 55 b, 55 c floating spherical projection 57a of, 57 b ... floated small projections 60 ... plate spring retainer S _R, S _L ... optical axis O ... center axis 61a ... circular aperture 61 ... ring-shaped aperture stop plate 2,63 ... bent leg 64, 65 ... light shielding skirt 66a, 66b, 66c ... indenter 71 ... washer 72 ... Screw 77 ... opening deformation restricting ribs

Claims (4)

[Claims] A first imaging lens and a second imaging lens, which are independent parts having the same optical axis and are parallel to each other, are mounted on a lens receiving surface of a light guide tube, and face a distance measurement target. And a first image forming optical system that forms parallax between the images and a first image forming system that converts the illuminance distribution of the image formed by the first image forming lens into an electric signal sequence.
A substrate on which a photoelectric conversion device and a second photoelectric conversion device for converting an illuminance distribution of an image formed by a second imaging lens into an electric signal sequence are fixed to a rear surface mounting surface of the light guide tube. In the apparatus, a distance measuring device is formed by fixing a spot to a surface of the substrate in a local region at the same position on a line including an optical axis interval on the back surfaces of the conversion devices. 2. The distance measuring apparatus according to claim 1, wherein the local area is a center-limited area centered on an optical axis. 3. The fixing region according to claim 1, wherein the local region is a fixing region using a thermosetting adhesive, and a concave portion for limiting a fixing margin is provided around the fixing region on the surface of the substrate. A distance measuring device characterized by being formed. 4. The base point according to claim 1, wherein, in a peripheral area of each of the two lenses, the base point is offset by the same distance on the same side on a line including the optical axis interval with respect to the optical axis. A distance measuring device, comprising a spot fixed to the lens receiving surface at a site.