JPS593308A - Method for aligning optical axes of sensor module for distance measurement - Google Patents

Abstract

PURPOSE:To improve the efficiency in aligning optical axes by turning an aperture member, which is disposed point-symmetrically with two openings of the same shape having an equal vertical angle so as to make the vertical angle coincident, by 1/2 of the vertical angle and measuring twice the output of a sensor module for distance measurement. CONSTITUTION:An aperture plate 25 consists of a light-shieldable member provided with openings 26, 27 of the same sectorial shape having an equal vertical angle theta center-symmetrically so as to make the vertical angles coincident, and is used in superposition with a diffusion plate in the exit pupil position. The plate 25 is first mounted in the position where the axial line of the image of the cross aperture by a lenslet coincides with the X-axis. The output of an electric charge coupling element constituting photodetectors A1, B1,...A5, B5 is observed and the average value on the side A and B of the photodetectors is read. A sensor module 11 is adjusted around the X-axis until both average values are made equal. The plate 25 is rotated by theta/2 clockwise, and the adjustment around the Y-axis is similarly accomplished.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for aligning the optical axis of a ranging sensor module in a camera.

A TTL (Through The Lens) type autofocus device can be roughly classified into a contrast detection type. Receive via 16.

FIG. 2 (Al shows the equivalent configuration of the above optical system excluding the semi-transparent mirror 15 and the total reflection mirror 16. Photometric sensor module ll, contact lens 17, lenslet plate 18)
, a sensor substrate 19 on which light receiving elements A and B are provided, and a lenslet plate 18 is a single plate having lenslets (microlenses made of acrylic resin). Although one or more lenslets may be provided, in this example, five lenslets are provided.

The light-receiving elements A and B are in pairs, and there are as many as there are lens reds, and these five sets of light-receiving elements AI.

BI % A2 + B2, . . . A5 # B5 are arranged in a row.

The light receiving elements A and B are arranged behind the lenslet symmetrically with respect to the axis X of the direct firing coordinate axis centered on the optical axis of the lenslet, and also symmetrically with respect to the other @Y. .

When the photographing lens 14 is at a specific position, the light passing through the center of the exit pupil 14A becomes parallel to the optical axis after passing through the contact lens 17. Also, at this time, each lenslet transmits the image 148' of the emission @14A to each set of light receiving element AI +
BI...A5. Make it on B5. Photodetector AI+”
As shown in FIG. 2 tb+ and FIG. 3, each set of I... has a shape obtained by dividing a circle into three equal parts. If the diameter of the exit pupil is a predetermined size, for any lens red, the image of the exit pupil formed on each set of light receiving elements AI, B, ... will be the same as that of each set of light receiving elements A, , B, ... It is constructed in a relationship that encompasses a circle (or a shape approximating it) formed by.

In FIG. 2, light receiving element A looks at the lower half of the exit pupil, and light receiving element B looks at the upper half of the exit pupil. When the object image formed by the photographing lens 14 is located at a position equivalent to the lower film surface 13, the light receiving elements A and B both receive the light flux from the same object image, so the outputs of both the light receiving elements A and H become equal. Therefore, the array A1. of light receiving elements A corresponding to all lenslets. The pattern of the outputs of A2, . . . taken out in time series completely matches that of the array BIIB2, . When the object image is shifted to either the front or back side of the plane equivalent to the film plane 13, the two patterns mentioned above change their shapes almost unchanged, but their temporal positions shift relative to each other. From the direction and magnitude of this deviation, it is possible to know the direction of the deviation from focus (front bin or rear bin) and its circumference. There are light receiving elements AIIBI, A21B2. ...
A5. The analog signals outputted in time series from the B5 are converted into digital values by an electric circuit (not shown) and then subjected to predetermined algorithm processing and focused.

The front bin and rear bin are determined, and ranging information is obtained.

This distance measurement information is displayed by a light emitting diode or the like in the finder, or is supplied to a motor drive circuit, and the motor drives the photographing lens 14 to the in-focus position.

Next, the conditions for obtaining correct distance measurement information in the above autofocus device are as follows:
A5. A case where B5 is constituted by a charge-coupled device will be explained. A charge-coupled device is a device that integrates the amount of light incident on each light-receiving element for a predetermined period of time to generate a charge, and extracts the charge in a time series at a voltage level. When the object is bright enough, a sufficient amount of light enters the light-receiving element, but when the object is dark, only a small amount of light enters the light-receiving element. Therefore, if the integration time of the amount of light is kept constant, the output of the light receiving element will vary significantly depending on the brightness of the object. Therefore, it is necessary to have a configuration in which the average value of the output of the light receiving element is detected and integration is continued until it reaches a certain level. With this configuration, stable ranging information can be obtained regardless of the brightness of the object. Furthermore, since this device is based on the premise that the outputs of both light receiving elements A and H are equal during focusing, it is essential that the ranging sensor module 11 directly faces the exit pupil. That is, the optical axis of the photographic lens and the optical axis of the lenslet must be parallel. If this parallel relationship is not properly established, the circular image of the exit pupil formed by the lens holes A and H will not match the circular image formed by the light receiving elements A and H. If it is not aligned to the left or right in Figure 3, it will simply be a loss of light quantity, but if it is shifted vertically, there will be a loss of light quantity and even if the light receiving element A is in focus.

A problem arises in that the outputs of B are not equal.

In other words, an out-of-focus signal is generated even though the object is in focus, which is inconvenient. Note that the above-described deviation in the left-right direction means the entire tilt of the sensor module 11 around X@, and the shift in the vertical direction means the tilt around Y@. Therefore, in order to avoid this problem of deviation, it is necessary to align the optical axis of the sensor module 11 during the camera manufacturing process.

In the conventional method for aligning the optical axis of a ranging sensor module, the photographing lens 14 is removed, and a diffuser plate 20 is placed at a predetermined exit pupil position P, as shown in FIG. Apply from the side.

Furthermore, a light-shielding aperture plate 22 having a semicircular opening 21 with a radius equal to the exit pupil as shown in FIG. 5 is superimposed on the diffuser plate 20.
The straight line part of the image of the two apertures formed by the lens red is made to coincide with the Y axis on the light receiving elements A and B. That is, the light flux passing through the semicircular opening 21 is made to enter only the right half (or left half) of the sensors A and H. Then, an oscilloscope is used to observe the integration end signal of the charge coupled device using the integration start signal of the charge coupled device as a trigger signal, and the time required for integration is read from the waveform. Next, the aperture plate 22 is rotated 1800 times and the integral time is read in the same manner. If both integration times are equal, sensor module 1 has no deviation of the optical axis in the left-right direction, that is, there is no inclination around Y@. If the two integral times are not equal, the sensor module 11 will be tilted around Y'@, so its installation is adjusted around Y@.

Next, insert the opening plate 22 into the slit-shaped opening 2 as shown in FIG.
3, and this aperture plate 24 is such that the center line of the image of the aperture 23 formed by the lenslet is aligned with the light receiving elements A and B.
Attach it so that it aligns with the exact center line of, that is, the X axis. If the sensor module 11 is not tilted, the light receiving element A,
Although the amount is small, the same amount of luminous flux enters B, so the outputs of light receiving elements A and B are equal L (if sensor module 11
is tilted, and the image of the aperture 23 and the light receiving elements A, B are relatively shifted, and the ratio of the amounts of light entering the light receiving elements A, H becomes f significantly.

Therefore, using the oscilloscope as a trigger signal to start transfer of the charge-coupled device, the light receiving elements AI + A2 . . . and B1 . Observe the output waveforms of B2... and compare their average levels. If both are equal, sensor module 11
There is no deviation of the optical axis around the X-axis. If the two are not equal, then the sensor module 11 will be
] Adjust around.

If necessary, the sensor module repeats adjustment around the Y@ axis and then around the X axis.

However, in such a method of aligning the optical axis of a distance measuring sensor module, when switching from adjustment around the Y axis to adjustment around the X@ axis, the aperture plates 22 and 24, which have completely different shapes, must be replaced. Although the aperture plate 22 can be easily rotated by 180 degrees, replacing the aperture plates 22 and 24 is time-consuming.

Also, the connection terminal to the oscilloscope must be changed accordingly. The oscilloscope's trigger probe gives the charge-coupled device integration start signal for adjustments around the Y axis, and the charge-coupled device transfer start signal for adjustments around X1ill, and the oscilloscope's observation probe gives the charge-coupled device transfer start signal for adjustments around For adjustment, it is necessary to give the charge-coupled device integration end signal, and for adjustment around the X-axis, it is necessary to give the output of the charge-coupled device.

Change the adjustment around the X axis and Y@. Since the aperture plate and the probe must be replaced every time, it is inefficient and unsuitable for manufacturing processes.

The present invention can improve the above-mentioned drawbacks, simplify the procedure for aligning the optical axes of distance-measuring sensor modules without reducing the accuracy of the optical axis alignment, and increase the efficiency of the optical axis alignment. The object of the present invention is to provide a method for aligning the optical axis of a distance measuring sensor module.

The present invention will be described below by way of examples with reference to the drawings.

In one embodiment of the present invention, an aperture plate 25 as shown in FIG. 7 is used to align the optical axis of the focus sensor module 11 in a camera equipped with the above-mentioned autofocus device.

The aperture plate 25 has the same sector-shaped apertures 26 with the same apex angle θ.
．． 27 is a light shielding member provided centrally symmetrically so that the apex angles coincide with each other, and the openings 26° and 27 are called cross apertures. This aperture plate 25 is an example of θ-90°, and is similar to the conventional aperture plate 25 in that it is overlapped with the diffuser plate 20 at the exit pupil position.
．． It is the same as 24.

First, as shown in FIG. 8, the aperture plate 25 is attached so that the @ line [equal dividing line] L'1 of the cross aperture images 26' and 27' formed by the lenslets coincides with the X axis. The charge-coupled device constituting the light-receiving element AI r BI r...A5 r B5 is driven by a drive circuit (not shown), and the transfer start signal is given to the oscilloscope as a trigger signal, and the output of the charge-coupled device is read by the oscilloscope. Observe and read the average value of the outputs of the light receiving elements AI + A2 + . . . and the average value of the outputs of the light receiving elements BI + B2 .

If these two average values are equal, the optical axis of the sensor module 11 will not be tilted around the X-axis. If the two average values are not equal, adjust the sensor/sample module 11 around X@ so that they become equal.

Next, the aperture plate 25 is rotated clockwise by θ/2−=45° in FIG. Align it with the X axis. i.e. cross aperture 26.2
The light beam passing through 7 enters the left half of the light receiving element A and the right half of the light receiving element B. Since the center of rotation of the sensor module J1 has already been placed on the X-axis due to the adjustment described above, if the sensor module 11 is not tilted by ye+t, the areas receiving the elements of the light-receiving elements A and B are equal. Therefore, connect the oscilloscope! ,''!, the average value of the output of light receiving element AI + A2... and light receiving element Bl
! It can be seen that the average values of the outputs of B2... remain consistent. However, Cenosamojile 11
If there is an inclination around Y@ of the cross aperture image 26
', 27' and light receiving elements A and B are connected to each other as shown in Figure 9.
Receiving elements A, , A2... and Bl r B2...
The average values of the outputs no longer match.

In this case, the sensor module 11 is adjusted around YIIl[l so that both average values match.

Repeat the above adjustment if necessary.

In this embodiment, it is possible to adjust the X@ and YIilII areas of the processor module by simply rotating the aperture plate 25 by 45 degrees, and the oscilloscope connection needs to be changed, which may cause the output waveform of the oscilloscope to change. View is X
Since both the adjustment around the @ axis and the adjustment around the Y axis are exactly the same, the optical axis alignment of the processor module can be performed with full efficiency during the manufacturing process.

FIG. 10 shows a modification 25' of the aperture plate. This opening plate 2
5' is an example in which θ=60°, and is used in the same manner as the aperture plate 25 described above. If this aperture plate 25' is used, the sensitivity for detecting the inclination of the processor module 11 around the Y-axis will be higher than when the aperture plate 25 is used, and the sensitivity for detecting the inclination around the X-axis will also be slightly higher. In general, the smaller θ is, the more
The detection sensitivity of the surrounding inclination becomes high, but if it becomes too small, the loss of light quantity becomes large, that is, the output of the light receiving element becomes small and the precision deteriorates. As long as θ is small (as long as the opening is kept triangular as shown in FIG. 11).

In the above embodiment, since the tilt of the sensor module is determined based on the output level of the charge-coupled device, the integration time of the charge-coupled device is not automatically controlled but is fixed. Any method may be used.

Therefore, the light receiving elements AI+B1...A5. B5 may be a photodiode array instead of a charge coupled device. Also, a pair of light receiving elements A.

The external shape formed by B is also not limited to a circular shape.

As described above, according to the present invention, two identical shapes having the same apex angle
An aperture member, in which the apertures are arranged point-symmetrically so that their apex angles match, is placed overlapping a diffuser plate at a predetermined exit pupil position to measure the output of the ranging sensor module. Since the output of the ranging sensor module is measured by rotating by 1/2 of the above vertical angle and the inclination of the optical axis of the ranging sensor module is adjusted, the aperture member is rotated by J/2 of the above vertical angle. The optical axes of the distance measuring sensor module can be completely aligned with just one step, and the efficiency of optical axes alignment can be increased by simplifying the procedure for aligning the optical axes without reducing precision.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an optical system in an example of an autofocus device, Fig. 2 fat is a diagram showing an equivalent configuration of the same optical system, The figure is a diagram for explaining the above optical system, Figure 4 is a diagram for explaining the optical axis alignment method of a conventional ranging sensor module, and Figures 5 and 6 show the aperture plate used in the same method. 7 is a plan view showing an aperture plate used in one embodiment of the present invention, FIGS. 8 and 9 are diagrams for explaining the same embodiment, and FIGS. 10 and 11 are It is a plan view showing a modified example of the aperture plate. 25...Aperture plate, 26.27...Aperture. ■June Requisition also Lθ prisoner ■J4■ Procedural amendment (voluntary) 1 Indication of incident 1981 Patent Application No. 113737 2 Name of the invention Method for aligning the optical axis of a distance measuring sensor module 3 Relationship with the case of the person making the amendment Patent issue
Address 1-3-6 Nakamagome, Ota-ku, Tokyo Name (674) Ricoh Co., Ltd. -4 Agent Address: 15
6 Address: 2-6-28 Sakuragaoka, Setagaya-ku, Tokyo Telephone: 03 (428) 5106 6 Contents of amendment/41 "Contact lens" on page 2, line 12 of the specification is corrected to "corrector lens.""Contactlenses" on page 3, line 6 of the same page is corrected to "corrector lens-1."
The cut opening may be formed as shown in FIG. ” is inserted. (41 Ibid., page 14, line 9, “and Figure 11”)
Corrected to ``Figure 2''. (Additional Figure 12 to Drawing 51.

Claims (1)

[Claims] One or more microlenses, and behind this microlens, these microlenses are arranged symmetrically with respect to one axis of orthogonal coordinate axes centered on the optical axis of this microlens and symmetrically with respect to the other axis. In a camera equipped with an autofocus device having a ranging sensor module having two light-receiving elements on which an exit pupil image at a predetermined position is formed by a lens, two apertures of the same shape with the same apex angle are formed. They were arranged point-symmetrically so that the apex angles matched. The output of the light receiving element is measured by placing an aperture member at a predetermined exit pupil position overlapping the diffuser plate, and the output of the light receiving element is measured by rotating the aperture member by the apex angle 1/2. . A method for aligning an optical axis of a ranging sensor module, comprising adjusting the inclination of the optical axis of the ranging sensor module based on these measurement results.