JPH10282405A - Focus detecting sensor module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a focus detecting module capable of reducing the number of parts by using parts inside the module in common. SOLUTION: This focus detecting sensor module 30 is constituted by arraying a transparent press plate 31, a condenser lens 32, a mirror unit 33, an auxiliary lens 34, a mask plate 35, a separator lens 36, and a CCD sensor unit 37 in order from a sub mirror side where light is made incident. The unit 33 has function as a module main body, and the lens 32 is fixed to the unit 33 by the plate 31. The plate 31 is constituted of a transparent plastic plate, infrared cut coat is performed on a surface 31a on a side where the light is made incident, and also a mask limiting the range of a luminous flux made incident on the lens 32 is formed on a back surface 31b on a light emitting side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus detection sensor module mainly used for a single-lens reflex camera and for detecting a focus state of a photographic lens on a subject.

[0002]

2. Description of the Related Art Conventionally, this type of focus detection sensor module has been used in a single-lens reflex camera having an autofocus function. The single-lens reflex camera has a quick return mirror for guiding a light beam incident through a photographing lens to a finder optical system when not exposed. The focus detection sensor module is generally arranged on the bottom side of the camera, and reflects a light beam transmitted through the central portion of the main mirror of the quick return mirror with a sub-mirror to enter the module.

In a conventional focus detection sensor module, a field mask plate having an aperture formed in a transmission portion, a condenser lens, a folding mirror, an infrared cut filter, a separator lens, and a sensor unit are arranged in this order from the light incident side. Each optical element is fixed to the module body.

[0004]

However, the above-mentioned conventional focus detection sensor module has a problem that the number of parts is large, so that the assembling man-hour is large and the occupied space is large.

The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide a focus detection module that can reduce the number of components by sharing components in the module. And

[0006]

In order to achieve the above object, a focus detection sensor module according to the present invention is characterized in that an infrared cut filter is also used as a holding member for a condenser lens. That is, the focus detection sensor module of the present invention is a focus detection sensor module that receives a part of the light beam transmitted through the photographing lens and detects a focus state of the photographing lens with respect to the subject. Fix each optical element to the module body so that the folding mirror, separator lens, and sensor unit are arranged in order,
The condenser lens is fixed to the module body by a holding plate having an infrared cut characteristic.

[0007] In addition to the function as an infrared cut filter, the holding plate can also function as a visual field mask. The function as an infrared cut filter can be achieved by applying an infrared cut coat on one surface or using a plastic plate having infrared cut characteristics. The field mask is formed by applying black paint to at least a portion of the holding plate that blocks light.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a focus detection sensor module according to the present invention will be described below. FIG. 1 is a perspective view showing a part of an optical system of a single-lens reflex camera. A light beam incident from a photographing lens (not shown) on the left side in the figure is a quick return mirror 1 disposed in the optical path of the incident light beam.
Incident at 0. The quick return mirror 10 is attached to a main mirror 11 that reflects an incident light beam upward in the figure and a central portion on the back side (the film side on the right side in the figure, not shown) of the main mirror 11, and A sub-mirror 12 is provided to reflect a light beam transmitted through the half mirror portion formed at the center portion downward in the drawing.

The quick return mirror 10 retreats from the optical path only at the moment of exposure when the shutter is released, and is located in the optical path as shown in the drawing when the shutter is not exposed. The light beam reflected by the main mirror 11 is guided to the finder optical system 20. The finder optical system 20 includes a focus plate 21, a pentaprism 22, and an eyepiece lens system 23. On the other hand, the light beam reflected by the sub-mirror 12 enters a focus detection sensor module 30 provided on the bottom of the camera body.

Next, details of the focus detection sensor module will be described with reference to FIG. 2 which is an exploded perspective view of the module. The focus detection sensor module 30 includes, in order from the sub-mirror 12 side where light is incident, a holding plate 31,
Condenser lens 32, mirror unit 33, auxiliary lens 34, mask plate 35, separator lens 36, CCD
The sensor units 37 are arranged and arranged. The mirror unit 33 has a function as a module main body, and other optical elements are fixed to the mirror unit 33.

The condenser lens 32 is arranged on the mirror unit 33 from the upper side in the figure, and is fixed by the pressing plate 31. The holding plate 31 is bonded to the mirror unit 33. On the other hand, the auxiliary lens 34, the mask plate 35, and the separator lens 36
The CCD sensor unit 37 is fixed to the mirror unit 33 by being adhered thereto and fixed between the mirror unit 33 and the CCD sensor unit 37. The condenser lens 32, the auxiliary lens 34, the mask plate 35, and the separator lens 36 are each provided with two positioning holes, and the mirror unit 33 has bosses (bosses) corresponding to these positioning holes. (Not shown).

The holding plate 31 is made of a transparent plastic plate, and has an infrared cut coat applied to a surface 31a on the light incident side and a back surface 3 serving as an emission side.
1b, a mask for limiting the range of the light beam incident on the condenser lens 32 is formed. The mask is formed by applying a black paint to a portion that blocks light indicated by hatching in FIG. The function of the holding plate 31 as an infrared cut filter can be achieved by using an infrared cut coat as described above or by using a plastic plate having infrared cut characteristics.

The focus detection sensor module 3 of the embodiment
Numeral 0 denotes a module having three distance measurement areas of the phase difference detection method. The images formed on the three transmission portions T1, T2, and T3 of the mask on the pressing plate 31 arranged near the film equivalent surface are shown. , And re-images on the line sensors 37a, 37b, 37c of the CCD sensor unit 37.

The condenser lens 32 is an integrally formed element having three lens portions 32a, 32b, 32c formed on one surface and a single plane formed on the other surface. Similarly, the auxiliary lens 34 and the separator lens 36 are integrally formed elements each having a lens portion formed on one surface and the other surface formed as a flat surface.

The three lens portions 3 of the condenser lens 32
The light beams transmitted through 2a, 32b, and 32c are reflected by the mirror unit 33, and the lens units 34a and 34a of the auxiliary lens 34
34b and 34c. The mask plate 35 has three pairs of openings 35a, 35b, 35c,
The three light beams emitted from the respective lens portions of No. 4 are respectively split into two, and are incident on three pairs of lens portions 36a, 36b and 36c of the separator lens 36. The condenser lens 32 is provided in order to allow light from the photographing lens to efficiently enter the lens portions 36a, 36b, and 36c of the separator lens 36.

The separator lens 36 is connected to the transmission portions T1, T2, T3 of the holding plate 31 and the line sensors 37a, 37a.
b and 37c are conjugated with each other, and the images formed in the respective transmissive portions are formed on the respective line sensors 37a, 37b and 37c as a pair of images. By detecting the relative position of the pair of images from the output of each line sensor, the in-focus state of the photographing lens with respect to the subject in each area can be detected. The camera performs focusing of the taking lens based on the output of one line sensor selected by a predetermined algorithm from the three,
The photographing lens is focused on a subject located at a position corresponding to the range that can be viewed by the selected line sensor.

On the pressing plate 31, the central transmitting portion T
Although the longitudinal direction of 2 and the longitudinal directions of the transmission portions T1 and T3 on both sides are orthogonal to each other, all three line sensors are arranged horizontally. This is because the luminous flux toward the sensors on both sides is rotated by 90 ° relative to the central luminous flux due to the arrangement of the mirrors of the mirror unit 33. That is,
The light beam reflected by the first mirror surface 33a at the center of the mirror unit 33 is deflected by 90 ° toward the center sensor, while the light beams toward the sensors on both sides are respectively centered by the second mirror surface 33b. After turning to the side,
Since the light beam is reflected by the third mirror surface 33c toward the CCD sensor unit 37, the light beam reflected twice is twisted by 90 ° with respect to the light beam reflected once by the first mirror surface 33a. Thus, in the visual field, the central sensor detects the phase difference in the horizontal direction, and the sensors on both sides detect the phase difference in the vertical direction.

[0018]

As described above, according to the present invention,
The holding plate for fixing the condenser lens to the module body has a function as an infrared cut filter, eliminating the need to provide the infrared cut filter as a separate component, reducing the number of parts and reducing the number of assembly steps. At the same time, the space occupied by the optical element can be reduced to promote downsizing of the module, or the degree of freedom in designing other optical components can be increased.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a part of an optical system of a single-lens reflex camera provided with a focus detection sensor module according to an embodiment.

FIG. 2 is an exploded perspective view of the focus detection sensor module according to the embodiment.

[Explanation of symbols]

 Reference Signs List 30 focus detection sensor module 31 holding plate 32 condenser lens 33 mirror unit (module body) 37 CCD sensor unit

Claims (5)

[Claims] 1. A focus detection sensor module for receiving a part of a light beam transmitted through a photographic lens and detecting a focus state of the photographic lens on a subject, wherein at least a condenser lens, a folding mirror, and a separator lens from the light incident side. A focus detection sensor module, wherein each optical element is fixed to the module main body so that the sensor units are sequentially arranged, and the condenser lens is fixed to the module main body by a holding plate having an infrared cut characteristic. 2. The focus detection sensor module according to claim 1, wherein a mask for limiting a range of a light beam incident on the condenser lens is formed on at least one surface of the pressing plate. 3. The focus detection sensor module according to claim 2, wherein the mask is formed on one surface of the holding plate and an infrared cut coat is applied on the other surface. 4. The focus detection sensor module according to claim 2, wherein the mask is formed by applying a black paint to a portion that blocks light. 5. The focus detection sensor module according to claim 1, wherein the pressing plate is a plastic plate having an infrared cut characteristic.