JPS6120844B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a focus detection device that calculates the distance to an object to be photographed.

A focus detection device that calculates the distance from the camera to the object to be photographed. Light from two different optical paths is detected by two groups of photoresponsive elements placed narrowly apart on the same surface of a single semiconductor wafer. A focus detection device has been proposed that receives light from each object and calculates the distance to the object from the output signals thereof.

In the case of this focus detection device, light is guided from two different optical paths using two groups of photoresponsive elements placed at a narrow interval on the same surface of one semiconductor wafer, so a complex optical configuration is required. In addition, by providing two sets of photoresponsive element groups on the same surface, a large area of the semiconductor wafer is required, which is disadvantageous in terms of cost.

An object of the present invention is to form photoresponsive element groups on the front and back sides of one semiconductor wafer, thereby obtaining the most space-efficient arrangement, thereby reducing differences in characteristics, reducing semiconductor space, and
Furthermore, it aims to reduce manufacturing costs.

According to the present invention, in a focus detection device including a first photoresponsive element group that receives light from a first optical path and a second photoresponsive element group that receives light from a second optical path. There is provided a focus detection device, characterized in that the first and second photoresponsive element groups are formed on a front surface and a front surface of a semiconductor wafer, respectively.

The present invention will be described below with reference to the drawings.

FIG. 1 shows a conventional focus detection device. FIG. 2 shows an embodiment of a focus detection device according to the present invention.

In FIG. 1, reference numerals 1 and 2 are first and second photoresponsive element groups, respectively, which are formed on the same surface of a semiconductor wafer 3 with a narrow interval therebetween. Reference numeral 4 denotes a movable mirror configured to be movable around an axis 5. 6 is a fixed mirror, and 7 is a prism. 8 and 9 are open holes. is a second optical path that connects light from the object to be photographed to the second photoresponsive element group 2 via the aperture 9, fixed mirror 6, and prism 7. or the first
The light including the object to be photographed is connected to the first photoresponsive element group 1 through the aperture 8, the movable mirror 4, and the prism 7 in an optical path. In the case of focus detection operation, the movable mirror 4 is rotated to detect a light pattern of an image connected to the second group of photoresponsive elements 2 and a light pattern of an image connected to the first group of photoresponsive elements 1. It is detected by known means that the two substantially coincide with each other.

In the case of this conventional configuration, it is known that the distance between the apertures 8 and 9 can be increased in order to improve the accuracy of focus detection. However, in order to converge the image onto the photoresponsive element groups 1 and 2 provided on the semiconductor wafer 3, the prism 7 is inevitably required. Therefore, the optical path of the prism 7,
It is necessary to improve the positional accuracy with respect to the semiconductor wafer 3, and also the accuracy of the relative position of the semiconductor wafer 3. In addition to conventionally requiring a complex optical system as described above, since two groups of photoresponsive elements are formed on the same surface of the semiconductor wafer 3, the area of the semiconductor wafer 3 becomes large and the cost becomes high. There were many disadvantages, such as:

Next, a second embodiment of the focus detection device according to the present invention, which eliminates various drawbacks seen in the conventional example, will be explained.
The explanation will be given with reference to the figures. In order to simplify the explanation, only the parts related to the present invention will be explained. The photoresponsive element groups 21 and 22 are formed on the front and back surfaces of the semiconductor wafer 23, respectively, as shown in FIG.
Place it in the center of the optical path. With this configuration, there is no need for an optical part such as a prism, which makes it easier to restrict the position with respect to the optical path, and by using both sides of the semiconductor wafer 23, the area is reduced. The effects of the present invention are significant, such as being advantageous in terms of cost.

Although the illustrative embodiment has been described in which the movable mirror 4 is rotated, the movable mirror may also be composed of only a fixed mirror. The present invention can be utilized not only in this example but also in the example shown in Japanese Patent Application Laid-open No. 138825/1983.

The present invention has been described in detail above. According to the present invention, the optical system configuration of the focus detection device can be greatly simplified, and the cost of semiconductor wafers can also be reduced.

[Brief explanation of the drawing]

FIG. 1 shows a conventional focus detection device, and FIG. 2 shows an embodiment of the present invention. , ... first and second optical paths, 3, 23 ... semiconductor wafer, 1, 21 ... first photoresponsive element group, 2, 22 ... second photoresponsive element group.

Claims (1)

[Claims] 1. A first photoresponsive element group that reflects the light on the first optical path with a reflecting mirror and receives the light, and a second photoresponsive element group that reflects the light on the second optical path with the reflecting mirror and receives the light. A focus detection device having a distance between a first optical path and a second optical path as a base line length, characterized in that the first and second photoresponsive element groups are formed on the front and back surfaces of a semiconductor wafer, respectively. Focus detection device.