JPH03293513A - Detecting apparatus for relative position of two images - Google Patents

Abstract

PURPOSE:To make the apparatus compact in size without deteriorating the detecting efficiency by constituting an optical path in an optical system to have a reflecting angle smaller than 45 deg. at each of the two reflecting parts. CONSTITUTION:This apparatus is comprised of a distance measuring optical system 20 which is an integrally molded piece of transparent plastic, and an IC package 10 fixed to the system 20 by an adhesive. Distance measuring lenses 21R, 21L are provided in the optical system 20, having metallic thin films 23R, 23L vapor deposited at an effective aperture part of a primary reflecting surface 2a and also metallic thin films 24R, 24L vapor deposited at an effective aperture part of a secondary reflecting surface 2b. An optical path in the optical system is arranged to have a reflecting angle theta (angle defined by a normal line of the reflecting surface and an incident light or reflecting light) smaller than 45 deg. at each of the reflecting surfaces 2a, 2b. Accordingly, the optical path length can be made large, whereby the focal length is elongated and the detecting efficiency is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a two-image relative position detection device equipped with a pair of left and right optical systems, and in particular, to detect images incident from the two optical systems.
For example, in a device that forms an image on a photosensor array and measures the amount of relative positional deviation between these two images, making it possible to measure the distance to an object or detect the in-focus state of a photographic lens, etc. The present invention relates to a technique for improving the detection performance or making the optical system more compact.

[Prior Art] Conventionally, as shown in FIG. 5, a distance measuring device used in an autofocus camera or the like has a symmetrical lens including a pair of left and right distance measuring lenses III and IL arranged in front of the camera. quantization circuits 3R and 3L that convert signals from the photosensor arrays 2m and 2t into digital signals, and digital signals from the quantization circuits 3m and 3L. There is an apparatus that employs an outside light triangular method, which is generally comprised of a distance measuring semiconductor integrated circuit chip 5 equipped with a logic section 4 that calculates a distance signal based on . The object T is separated by the base line length B from the distance measuring lens 1 m, and its image is formed by the photosensor array 2 m of the chip 5.

They are each projected onto 2L. The distance d to the subject T is given by the following equation based on the principle of triangulation.

Distance to sensor arrays 2R and 2L (distance measurement lens 1m)
, equal to the focal length of LL),x,,x.

is the distance between the image point on the photosensor array 2□, 2 and the image point when the subject T is at infinity, χ(X++Xz)
is the relative shift amount (phase amount) of the subject on the photosensor array 21.2L.

The actual structure of this distance measuring device is, for example, as shown in FIG. 6, which includes plano-convex distance measuring lenses Ill and LL, which constitute the imaging system placed in front of the camera, and which gives a declination angle to the light beam. It is equipped with a distance measuring optical device 9 consisting of reflective mirrors M, ML, a right angle prism 6 and a case 8, which are optical elements constituting a deflection system, and an IC package 7 in which a distance measuring semiconductor chip 5 is enclosed. . This IC package 7 is, for example, a ceramic package, and as shown in FIG.
After mounting the photosensor arrays on the photosensor arrays 2R and 2L, a cover glass 7b serving as a transparent window is attached onto the photosensor arrays 2R and 2L.

Base line length B and focal length f of this distance measuring optical device 9.

must be determined from the requirements of ranging performance or focusing performance. On the other hand, since the chip 5 needs to be as small as possible to reduce cost, the distance between the base line length B and the photosensor arrays 2N and 2L is The distances C do not match, so
Distance measurement lens 11. It is necessary to deflect the light incident from the IL in order to narrow the distance between them.

Further, this distance measuring device can also be used as a focus detection means for detecting the in-focus state of the imaging optical system by dividing a part of the light focused by another imaging optical system. A conventional example of this focus detection method is shown in FIG. In the figure, the imaging optical system constitutes a zoom lens consisting of a focus lens 11, a variable magnification lens I2, and an imaging lens 13. Between the variable magnification lens 12 and the imaging lens 13, light is transmitted. When the imaging optical system is focused, the light becomes parallel. This variable magnification lens 1
A beam splitter 14 having a half mirror 14a is inserted between the imaging lens 2 and the imaging lens 13 to split a part of the photographing light beam and guide it downward. And focus lens 11
A pair of ranging lenses 1, . . . 1. through the photosensor array 2-. located at a position conjugate with the film plane F with respect to the focus lens 11. Introduce on 2L. In this way, by detecting the position where the light beam reaches above the photosensor arrays 2g, 2, it is possible to detect whether or not the imaging optical system is in focus. Here, the focus shift amount Δ on the film plane F is determined from the shift amount (phase amount) X of the images on the photosensor arrays 2R and 2L using the following equation.

It is distance. Note that 17 in the figure is a light shielding plate for preventing interference between left and right beams of light, and 19 and 20 are a rank pinion and a motor for focus adjustment that act on the focus lens 11.

Furthermore, as an example of a device having another form based on the same principle as the distance measuring device shown in FIG. 6, as shown in FIG. There are things made of goods.

The height of this optical system! Then, the focal length of the optical system is f9
must have the value shown in the formula below.

The height, α, is the contribution of the IC package thickness.

After this distance measuring optical device 9 is precisely positioned with respect to the transparent plastic IC package 10 in which the chip 5 is enclosed, it is bonded to the bonding surface 22 using, for example, an ultraviolet curing resin.

[Problem to be solved by the invention]

2. Description of the Related Art In recent years, cameras, video cameras, and the like equipped with distance measuring devices have become more compact, and there is also a demand for reducing the size of distance measuring devices. here,
The baseline length B determines the size of the front surface of the device as a distance measuring device, and as a focus detection device, it should be set in accordance with the width of the light beam, which is being reduced as the imaging device becomes smaller. Therefore, in order to make the distance measuring device more compact, it is necessary to shorten the baseline length B. However, if the minimum detection pitch of the photosensor arrays 211, 2L is P, then the detection distance can be calculated from equations (1) and (2). In order to improve the detection performance by increasing the maximum measurement value of d or decreasing the minimum detection width of the amount of defocus Δ, it is necessary to increase B·fe/P. For example, if the baseline length B is shortened, in order to maintain the detection performance, equations (1) and (2)
As shown in , it is necessary to lengthen the focal length fe, which increases the height l of the optical system and reduces the brightness (F number) of the optical system.Ensuring the brightness of the optical system In order to achieve this, it is necessary to increase the aperture of the distance measuring lens 11.IL, but there are restrictions due to the base line length B and the relationship with other optical components, and it is currently impossible to avoid a decrease in the F value. Also,
The height of the optical system! Of course, the detection performance also decreases when the focal length re is shortened.

Therefore, the present invention is intended to solve the above problems, and the problem is to change the optical path arrangement within the optical system.
In addition to increasing the focal length fe of the distance measuring device, the distance measuring lens 11. It is an object of the present invention to provide a two-image relative position detection device that can be made compact without deteriorating detection performance by allowing a large effective aperture of LL.

[Means to solve the problem]

In order to solve the above-mentioned problems, a pair of left and right optical systems of the same type is used, which is composed of an imaging system and a deflection system having at least two reflecting parts that deflect the light that has passed through the imaging system. In a two-image relative position detection device that images an object on each of the left and right sensor portions of a light receiving device for relative position detection, the means taken by the present invention is as follows:
It is configured to have a reflection angle (angle between the normal to the reflecting surface and the incident light or reflected light) smaller than . Here, the light incident on each of the left and right optical systems may be introduced into the sensor section on the opposite side. Furthermore, the optical path after the first reflection l within the optical system may be taken out of the plane that includes the left and right optical axes of the imaging system.

In the above-mentioned optical system, each of the left and right optical systems may be formed by integral molding of plastic, or the entire left and right optical system may be formed by integral molding of plastic.

[Effect]

According to this method, since the deflection system is configured so that the two reflection angles are 45° or less, it is possible to increase the distance between the two reflection parts, although it is limited by the height of the optical system. This is possible, and since the optical path within the optical system is in a folded form, a longer optical path length can be secured even within an optical system with the same dimensions as the conventional optical system. Therefore, it is possible to increase the focal length of the optical system, and the detection performance determined by the baseline length and focal length (maximum measurement distance when measuring distance, minimum amount of focal shift when detecting focus) The detection width) can be improved, or the optical system can be made compact while maintaining detection performance. Here, if the optical path is configured so that the light incident on the left and right optical systems is introduced into the opposite sensor sections, the optical path length can be made even longer.

Furthermore, if the optical path within the deflection system is configured to deviate from the plane that includes the optical axes of the left and right imaging systems, it goes without saying that the optical path length within the deflection system can be made longer as in the above method. Since the reflection section of the deflection system can be installed at a position apart from the installation locations of the left and right imaging systems, the effective aperture of the imaging system can be increased. Therefore, when using an optical system with the same dimensions as the conventional one, the brightness (F value) of the optical system can be made larger than the conventional one, and
If the same brightness as the conventional one is to be maintained, the optical system can be made more compact than the conventional one.

When the optical system is made of left and right plastic molded parts, or left and right parts integrated, the number of parts can be reduced and assembly and adjustment of the apparatus can be facilitated.

〔Example〕

Next, the present invention will be described in detail with reference to the drawings.

First Embodiment> First, a first embodiment will be described with reference to FIG. This embodiment includes a distance measuring optical system 20 formed as an integrally molded product of transparent plastic, and an optical system 20 that is adhesively fixed thereto.
C package 10. The distance measuring optical system 20 and the IC package 10 are adjusted in position with an ultraviolet curing resin applied to their joint surfaces 22, and when the positioning is completed, they are fixed by irradiating them with ultraviolet rays. Distance measuring optical system 2
0 has a distance measuring lens 21. ．． 21L is provided, and a metal thin film 23.21L is provided on the effective aperture portion of the reflective surface 2a. .

23L is a metal thin film 24m on the effective aperture part of the reflective surface 2b.
, 24L are deposited, respectively. The reason why a metal thin film is deposited only on the effective aperture portion is to prevent excess reflected light from being generated and becoming stray light. Since the cross-sectional shape of the incident light beam changes as it travels, the metal thin films 231, 231 and the metal thin films 241, 24L are deposited in different shapes. The light that has passed through the distance measuring optical system 20 passes through the adhesive surface 22 and reaches the photosensor array 2 of the integrated circuit chip 5 installed inside the IC package 10.
Images are formed on R and 2L.

In this example, the focal path Mf is given by the following equation.

The line length, C is the distance between the optical axes of the light that reaches the photosensor array 2, 1.2L, θ is the reflection angle of the light on the primary reflection surface 2a and the secondary reflection surface 2b, and l is the distance measurement optical system 20. height,
α is the contribution of the IC package thickness. Type 20 (4)
Comparing with equation (3), we get: In this equation, the height l of the distance measuring optical system is at least: B-C'1 In this embodiment, the base line length B=15 mm, the photosensor array 2. ．． 2L spacing C = 3 mm, reflection angle θ = 20
°, the height of the ranging optical system 2o is 41! = 10 mm, the refractive index of the distance measuring optical system 20 is n = 1.5, and assuming that the contribution α near the adhesive surface 22 can be ignored, then by substituting the respective values into 2 (4), the focal length f8 -17.7mm.

Based on formula (3) of the conventional example, the above base line length B and interval C1
and by substituting the value of the refractive index n, the focal length L = 17.7 m
When trying to obtain m, the height of the distance measuring optical system is f = 20.5 m.
m, which requires about twice the height as in this embodiment.

In this way, in this embodiment, even if the same focal length as the conventional one is set, the optical system can be designed more compactly than the conventional one.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, the distance measuring optical system 3o includes distance measuring lens sections 31m and 31t, metal thin films 33m and 33t are provided on the effective reflective portion of the -order reflective surface 3a, and metal thin films 33m and 33t are provided on the effective reflective portion of the secondary reflective surface 3b. Metal thin films 34R and 34L are deposited on the -order reflection surface 3a and the secondary reflection surface 3b, respectively.
By adjusting the angle of It is designed to form an image.

In this embodiment, the light incident on the left and right optical systems reaches the photosensor array on the opposite side, and the optical path length can be increased by the amount that the optical paths intersect with each other. The focal length of this embodiment is expressed as follows, which is longer than the focal length of the first embodiment expressed by equation (4). Furthermore, when this embodiment is used as a distance measuring device, contrary to the first embodiment, when the subject approaches, the light beams above the photosensor array 21.2 shift inward, so that the subject is at an infinite distance. The optical axes matched can be set at the outermost position on the photosensor array 21.2L. Therefore, c'>c (the interval between the luminous fluxes in the first embodiment), which further increases the optical path length.

In this example, the base line length B = 15 mm, the photosensor array 2 m, the distance between the optical axes above 2 C' = 5 mm, and the reflection angle θ
= 30°, the height f of the distance measuring optical system 20 = 10 mm, the refractive index n of the distance measuring optical system 20 = 1°5, and assuming that the contribution α of the IC package can be ignored, then equation (5) is obtained. By substituting each numerical value, the focal length f* = 18.2 mm. The focal length with the same value as this is the base line length B with the same value as above,
If you try to realize it with the conventional example of interval C' and refractive index n,
The height of the distance measuring optical system is 21.3 mm, which requires more than twice the height.

<Third Embodiment> A third embodiment of the present invention will be described with reference to FIG. In this embodiment, the normal line of the primary reflection surface 4a and the secondary reflection surface 4b of the distance measurement optical system 40 is off the plane containing the optical axes of the distance measurement lenses 41m and 41L, and the distance measurement lens 41 □
The light incident from 41L and 41L is reflected by the -fire incident surface 4a and takes an optical path toward the front side of FIG. 3(a), and then reaches the secondary reflection surface 4b.
After being reflected vertically downward at the photo sensor array 2 m.

2. Image is formed above.

According to this distance measuring optical system 40, as in the first embodiment, the optical path length can be increased (that is, the focal length can be increased), and the secondary reflective surface 4b can be used as the distance measuring lens 41□. 41
There is no need to form between the distance measuring lenses 41.L and 41.L. Since it can be formed at a location off the plane that includes the optical axes of I and 41L, it is possible to increase the effective aperture of the distance measurement lenses 41m and 41L, and the brightness of the distance measurement optical system (F value) can be increased. Therefore, even if the baseline length B is set to be close to the distance C between the photosensor arrays 2R and 2L, there is a large degree of freedom in designing the optical system, and the ranging lenses 41m and 41L have sufficient values.
It is possible to secure a caliber of

Fourth Embodiment In the fourth embodiment shown in FIG. 4, the distance measuring optical system 50 has almost the same basic structure as the third embodiment, but - By making the secondary reflecting surface 5b larger and forming the slope of the secondary reflecting surface 5b in the opposite left and right directions, the left and right lights incident on the ranging lenses 51R and 51L reach the photosensor arrays 21 and 2L on the opposite left and right sides, respectively. It is set as follows. In this embodiment, as in the third embodiment, the effective aperture of the ranging lens 51 and 51L is limited only by the base line length B without being obstructed by the secondary reflective surface 5b, so the ranging optical system 50 In addition to increasing the brightness, the focal length can be further increased by crossing the left and right optical paths as described above, making it possible to create a more compact optical system without sacrificing detection performance. can be formed.

[Effects of the Invention] As explained above, the present invention makes the reflection angle of light in the optical system of a two-image relative position detection device smaller than before and changes the direction of deflection of light, thereby increasing the optical path length and the like. Since it is characterized in that the arrangement of the reflecting portions is changed, the following effects are achieved.

■ By keeping the reflection angle of the deflection system below 45°,
Since the optical path length within the optical system can be larger than before, the focal length can be increased to improve detection performance (maximum measurement distance when measuring distance, minimum amount of focal shift when detecting focus). The detection width) can be improved, and the optical system can be made more compact.

(2) If the optical path is configured so that the light incident on the left and right optical systems is introduced into the sensor sections on opposite sides, the optical path length can be made even longer.

■ If the deflection system is configured so that the optical path within the optical system deviates from the plane that includes the optical axes of the left and right imaging systems, the reflecting part of the deflection system also deviates from the plane that includes the optical axes of the left and right imaging systems. Therefore, the effective aperture of the imaging system can be made as large as possible with respect to the baseline length without being hindered by the structure of the reflecting section. Therefore, even when the focal length is increased, the brightness of the optical system can be ensured, or
The optical system can be made more compact while ensuring detection performance and optical system brightness.

■ If the left and right optical systems are each made of integrally molded plastic, or if the entire left and right optical system is made of integrally molded plastic, the number of parts will be reduced, making assembly and adjustment of the optical system much easier. becomes.

[Brief explanation of drawings]

FIG. 1(a) is a partially cutaway front view showing the structure of a distance measuring device according to a first embodiment of the present invention, and FIG. 1(b) is a plan view showing the structure of a distance measuring device according to the same embodiment. be. FIG. 2(a) is a partially cutaway front view showing the structure of a distance measuring device according to a second embodiment of the present invention, and FIG. 2(b) is a plan view showing the structure of a distance measuring device according to the same embodiment. be. FIG. 3(a) is a perspective view showing the structure of a distance measuring device according to a third embodiment of the present invention, and FIG. 3(b) is a plan view showing the structure of a distance measuring device according to the third embodiment. FIG. 3(c) is a side view showing the structure of the distance measuring device of the same embodiment. FIG. 4(a) is a perspective view showing the structure of a distance measuring device according to a fourth embodiment of the present invention, and FIG. 4(b) is a plan view showing the structure of a distance measuring device according to the fourth embodiment. FIG. 4(c) is a side view showing the structure of the distance measuring device of the same embodiment. FIG. 5 is a schematic diagram showing the principle of distance measurement using the outside light triangular method. FIG. 6 is a longitudinal sectional view showing the actual structure of a conventional distance measuring device. FIG. 7(a) is a plan view of an IC package in a conventional distance measuring device, and FIG. 7(b) is a partially cutaway front view of the same IC package. FIG. 8 is a conceptual diagram showing a method for detecting the in-focus state of an imaging device using a distance measuring device. FIG. 9(a) is a front view showing a conventional distance measuring device in which the distance measuring optical system is formed of an integrally molded plastic product, and FIG. 9(b)
) is a plan view showing the distance measuring device. [Explanation of symbols] 21.2L...Photo sensor array 5...Integrated circuit chip 10...IC packages 2a, 3a, 4a, 5a...-Next reflecting surfaces 2b, 3b,
4b, 5b...Secondary reflective surface 20.30, 40.50.
... Distance measuring optical system 21*, 2LL, 31*
, 3 It, 41R5'Ilc, 51R, 51t
... Distance measuring lens 22 ... cemented surfaces 23R, 23L, 24R, 24t, 33++. 33L, 34R, 34L, 43e, 43't. 44R, 44L, 531, 53L, 54m. 54,...Metal thin film.

Claims (5)

[Claims] (1) Relative position detection is performed through a pair of identical left and right optical systems each consisting of an imaging system and a deflection system having at least two reflecting parts that deflect the light that has passed through the imaging system. In a two-image relative position detection device that images an object on each of the left and right sensor sections of a semiconductor integrated circuit chip, the optical path within the optical system has a reflection angle smaller than 45° at each of the two reflection sections. A two-image relative position detection device characterized by: (2) The two-image relative position detection device according to claim 1, wherein the light incident on each of the left and right optical systems is introduced into the left and right sensor sections on opposite sides. (3) The optical path after passing through the first reflecting section in the optical system is out of a plane including the left and right optical axes of the imaging system. 2. The two-image relative position detection device described in 2. (4) The two-image relative position detection device according to any one of claims 1 to 3, wherein the left and right optical systems are each formed by integral molding of plastic. (5) The two-image relative position detection device according to any one of claims 1 to 3, wherein the left and right optical systems are integrally formed of plastic.