JP2005301168A - Focus control device for camera module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a focus control device for a camera module, in which the focus control for infinite and finite image pickup distances can be performed with a single operation for proper production efficiency. <P>SOLUTION: The focus control device for a camera module to control a focus by using test charts is provided with a magnifying glass 6, and first chart 2 and second charts 3-5 which are used for test charts. The first chart 2 is arranged on a test chart side focal distance 9, and the second charts 3-5 are arranged on the magnifying glass 6 side from the test chart side focal distance 9. The first chart 2 and the second charts 3-5 are arranged so as not to overlap, as seen from the camera module 7 side. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates generally to a focus adjustment device for a camera module, and more specifically, so that focus adjustment for an imaging distance at infinity and a plurality of finite distances can be performed at once without a plurality of trials. The present invention relates to an improved focus adjustment device for a camera module.

  In recent years, the mounting rate of mobile phone camera modules has increased rapidly, and the production quantity has increased. Since this camera module is used in a mobile phone, it is basically small and thin, and has a feature that the lens outer shape is remarkably smaller than that of a normal camera such as a 35 mm camera. Against this backdrop, the lens unit also has high performance and high functionality (AF (auto focus)) in conjunction with the increase in the number of pixels of CCD (charge coupled device) and CMOS (complementary metal oxide semiconductor) sensors used in modules. ), Zoom, etc.) are used, and it is required that the image is not blurred not only at infinity but also at a plurality of imaging distances at finite distance.

  In the past, infinity was simulated by collimating the optical path from the test chart with a collimator lens. FIG. 5 is a conceptual diagram of a conventional mobile phone focus adjustment device that simulates infinity with a collimator lens.

  The focus adjustment device includes an LED light source 20, a transmission chart 21, and a collimator lens 22. The design of the transmissive chart 21 is projected by the LED light source 20. The chart 21 is placed at a focal distance 25 from the collimator lens 22. The mobile phone camera module 23 performs focus adjustment by rotating the lens unit 24 to the left and right so as to be within the range of the depth of focus. A camera module 23 is connected to the image capturing board 26. An image capturing board 26 is connected to a personal computer (PC) 27. A monitor 28 is connected to the PC 27. The entire output of the camera module 23 is displayed as an image on a part 29 of the screen of the monitor 28. The portion indicated by reference number 30 is an image of the outer periphery of the collimator lens 22 as viewed by the camera module 23. A portion indicated by reference numeral 31 is an image of the chart 21 as seen by the camera module 23. The portion indicated by reference number 32 is a part of the screen of the monitor 28, and the focus value of the portion indicated by reference number 31 is relatively displayed in a bar graph. The focus is adjusted by optimizing the bar graph.

  FIG. 6 is a diagram illustrating the concept of a collimator lens. The chart 52 is placed at the focal length f of the collimator lens 51. When viewed from A, the chart 52 appears to be at infinity. Therefore, infinity is simulated.

  Conventionally, focus adjustment was performed only at infinity, but focus adjustment at finite distance has become necessary for higher functionality.

  FIG. 7 is a conceptual diagram of a conventional finite distance focus adjustment apparatus.

  The reflective chart 33 is placed at an actual distance 37 from the mobile phone camera module 35. The design of the reflective chart 33 is projected by the light sources 34a, 34b, 34c, 34d. The optical path is input to the mobile phone camera module. This focus adjustment device does not use a collimator lens. The focus adjustment is performed by rotating the lens portion 36 of the camera module 35 for mobile phone left and right. It is considered good if it is within the depth of focus and within the adjustment.

  A camera module 35 is connected to the image capturing board 38. An image capture board 38 is connected to the PC 39. A monitor 40 is connected to the PC 39. The entire output of the camera module 35 is displayed as an image on a part 41 of the screen of the monitor 40. A portion indicated by reference numeral 42 is an image of the chart 33 viewed by the camera module 35. The portion indicated by reference number 43 is a part of the screen of the monitor 40 and relatively displays the focus value of the portion indicated by reference number 42 in a bar graph. The focus is adjusted by optimizing the bar graph.

  In FIG. 5, a transmissive type is used for the chart and a reflective type is used for FIG. 7, but either may be used.

  In relation to the present invention, Patent Document 1 discloses a flange adjusting device for a TV camera as shown in FIG. The flange adjusting device for the TV camera includes a collimator lens 47. The charts 45 and 46 are arranged slightly behind and in front of the chart 44 at a position separating the focal length 50 on the chart side of the collimator lens 47. First, a chart is placed at the focal length 50, flange adjustment is performed, and then flange adjustment is performed before and after that. The TV camera 48 includes a lens 49 capable of flange back adjustment, and performs flange adjustment by rotating the lens portion 49 left and right. The optimization of the flange back is performed based on the output when the charts 44, 45, and 46 are viewed with the TV camera 48.

Japanese Patent Laid-Open No. 58-85684

  As described above, the focus adjustment of the conventional mobile phone camera module is simulated by collimating the optical path from the test chart at infinity with a collimator lens, and placing the test chart at the actual distance for finite distance, Each optical path was input to the camera module. Therefore, there is no problem when focus adjustment is performed at an imaging distance of only infinity or only at finite distance, but when focus adjustment is required for both imaging distances of infinity and finite distance, it cannot be performed at once, but multiple times. This was a major problem in terms of production efficiency. Further, the disclosed technique of Patent Document 1 has a problem in that it is necessary to change and adjust the chart position each time, which takes time.

  The present invention has been made to solve the above-described problems, and provides a camera module focus adjustment apparatus improved so that focus adjustment can be performed at a time for imaging distances at infinity and finite distance. With the goal.

  The present invention relates to a focus adjustment device for a camera module that performs focus adjustment using a test chart, and includes a magnifying glass and at least a first chart and a second chart serving as the test chart. The first chart is arranged at the test chart side focal length of the magnifying glass, and the second chart is arranged on the magnifying glass side from the test chart side focal length of the magnifying glass. The first chart and the second chart are arranged so as not to overlap each other when the magnifying glass is viewed from the camera module side.

  According to the present invention, the first chart is arranged at the test chart side focal length of the magnifier, and the second chart is arranged at the magnifier side from the test chart side focal length of the magnifier, Further, the first chart and the second chart are arranged so as not to overlap each other when the magnifying glass is viewed from the camera module side. The imaging distance of finite distance can be simulated simultaneously.

  According to a preferred embodiment of the present invention, the patterns of the first chart and the second chart include black and white stripes or checkered patterns.

  According to a further preferred embodiment of the present invention, the pitch of the pattern is equal to or more than two pixels of the image sensor in the camera module and does not become an integral multiple. By constituting in this way, aliasing distortion and beat can be avoided.

  According to the present invention, it is possible to achieve an excellent effect that the focus adjustment for the imaging distances at infinity and a plurality of finite distances can be performed at one time without performing a plurality of trials.

  In order to simulate an imaging distance at infinity, the chart for infinity is placed at the chart side focal point of the magnifying glass (magnifying lens). In order to simulate an imaging distance at a finite distance, a finite distance chart is placed closer to the magnifying glass than the chart side focal point of the magnifying glass. The charts are arranged vertically and horizontally so that they do not overlap each other when the magnifier is viewed from the camera module side. As a result, the entire chart is seen in the imaging state, and as a result, imaging distances of infinity and finite can be simulated simultaneously. Hereinafter, examples of the present invention will be described in more detail with reference to the drawings.

  FIG. 1A is a conceptual diagram of a focus adjustment device for a mobile phone camera module according to an embodiment of the present invention. The focus adjustment device includes an LED light source 1, transmissive charts 2, 3, 4, 5 and a magnifying glass 6. Chart 2 is a chart for infinity, and is placed on the chart side of the magnifying glass 6 with a focal length 9 therebetween. Charts 3, 4, and 5 are finite distance charts and are placed closer to the magnifying glass 6 than the chart side focal point of the magnifying glass 6.

  The symbols of the charts 2, 3, 4, and 5 are, for example, a black and white checkered pattern or a stripe pattern as shown in FIG. It is preferable that the pattern pitch is two pixels or more of the sensor (imaging device) in the camera module 7 and does not become an integral multiple. By constituting in this way, aliasing distortion and beat can be avoided.

  The symbols of the transmission charts 2, 3, 4, and 5 are projected by the LED light source 1. The mobile phone camera module 7 performs focus adjustment by rotating the lens unit 8 left and right. A camera module 7 is connected to the image capturing board 10. An image capture board 10 is connected to the PC 11. A monitor 12 is connected to the PC 11. The entire output of the camera module 7 is displayed as an image on a part 13 of the screen of the monitor 12. The portion indicated by reference numeral 14 is an image of the outer periphery of the magnifying glass 6 as seen by the camera module 7. The portion indicated by reference numeral 15 is an image of the charts 2, 3, 4, and 5 viewed through the magnifying glass 6 with the camera module 7. The portion indicated by reference number 16 is a part of the screen of the monitor 12 and relatively displays the focus value of the portion indicated by reference number 15 in a bar graph.

  FIG. 1B is an enlarged view of a portion indicated by reference numeral 14 in FIG. 1A, and shows the arrangement of charts 2, 3, 4, and 5. FIG. 3 is an enlarged view of a portion indicated by reference numeral 16 in FIG. 1 (A), and shows a relative bar graph display of the focus values of charts 2, 3, 4, and 5. In FIG. The focus is adjusted by optimizing the bar graph. Referring to FIG. 1B, the measurement points in the chart image are measured at a portion where each chart image is close (in the figure, near the optical axis, that is, the position of abcd). Good to do.

  FIG. 4 is a conceptual diagram of a magnifying glass used in this embodiment. With reference to FIG. 4A, the chart 54 is placed at the focal length f of the magnifying glass 53. When viewed from B, the chart 54 appears to be at infinity. Therefore, infinity is simulated. Referring to FIG. 4B, when the chart 54 is placed on the magnifying glass 53 side with respect to the focal length f of the magnifying glass 53, the chart 54 appears to be at a finite distance 57 when viewed from B. Therefore, in this case, finite distance is simulated.

  Thus, according to the present embodiment, all charts at infinity and finite distance can be seen in the imaging state, and as a result, imaging distances at infinity and finite distance can be simulated simultaneously. As a result, focus adjustment can be performed at once for imaging distances at infinity and finite.

  In the above embodiment, the mobile phone camera module is exemplified as the camera module, but the present invention is not limited to this.

  Moreover, in the said Example, although the transmission type was illustrated as a chart, a reflection type may be sufficient.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention provides a focus adjustment device for a camera module with good production efficiency, in which focus adjustment can be performed at once for infinite and finite imaging distances.

It is a conceptual diagram of the focus adjustment apparatus of the camera module for mobile phones concerning an Example. It is a figure which shows an example of the design of a chart. It is a figure which shows the example of a display of the relative bar graph of the focus value of a chart. It is a conceptual diagram of the magnifier used in a present Example. It is a conceptual diagram of the conventional focus adjustment apparatus. It is a figure which shows the concept of a collimator lens. It is a conceptual diagram of the conventional finite distance focus adjustment apparatus. It is a conceptual diagram of the flange adjustment apparatus of the conventional TV camera.

Explanation of symbols

1 LED
2, 3, 4, 5 Chart 6 Magnifier 7 Camera module 8 Lens unit 9 Focal length 10 Image capture board 11 PC
12 Monitor 13 Part of the monitor screen 14 Image of the outer periphery of the magnifier viewed with the camera module 15 Chart image viewed through the magnifier with the camera module 16 Bar graph display

Claims (3)

A camera module focus adjustment device that performs focus adjustment using a test chart,
A magnifier,
The test chart, comprising at least a first chart and a second chart,
The first chart is disposed at a test chart side focal length of the magnifying glass,
The second chart is arranged on the magnifying glass side from the test chart side focal length of the magnifying glass,
The camera module focus adjustment apparatus, wherein the first chart and the second chart are arranged so as not to overlap each other when the magnifier is viewed from the camera module side.   The camera module focus adjusting apparatus according to claim 1, wherein the patterns of the first chart and the second chart include a black and white stripe or a checkered pattern. The focus adjustment device for a camera module according to claim 2, wherein the pitch of the pattern is equal to or more than two pixels of the image sensor in the camera module and does not become an integral multiple.

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