Optical position detecting unit and optical coordinate input unit

• US 5,572,251 A
• Filed: 10/28/1994
• Issued: 11/05/1996
• Est. Priority Date: 03/17/1994
• Status: Expired due to Fees

• Current Assignee: Wacom Co Limited (Wacom)
• Original Assignee: Wacom Co Limited (Wacom)
• Inventors: Ogawa, Yasuji
• Primary Examiner(s): GARBER, WENDY RAE
• Application Number:
  US08/330,457
• Time in Patent Office: 739 Days
• Field of Search: 348/744, 348/61, 348/15, 348/143, 348/141, 348/169, 348/207, 345/145, 345/157, 345/158, 345/180, 345/181, 345/179
• US Class Current: 348/207.99
• CPC Class Codes: G06F 3/0321 by optically sensing the absolute position with respect to a regularly patterned surface forming a passive digitiser, e.g. pen optically detecting position indicative tags printed on a paper sheet constructional details of pen-shaped pointing devices G06F3/03545, G06F3/03542, G06F3/037
• CPC Class Codes: G06F 3/0386 for light pen

Abstract

An optical position detecting unit which includes: an image pickup device having a pixel array region, an imaging lens for forming an image of a light-emitting point, a converging lens for converging light come from the light-emitting point image formed by the imaging lens onto the pixel array region, a pattern member having a pattern which contains code information uniquely corresponding to the position of the light-emitting point and disposed on a path of light from the light-emitting point and at a position near the light-emitting point image, and a signal processing unit for extracting information of the position of the light-emitting point by using code information contained in an image of the pattern projected onto the pixel array region of the image pickup device on the basis of image data generated by the image of the projected pattern.

Claims

1. An optical position detecting unit for optically detecting a position of a freely movable light point comprising:

an image sensor having a pixel array region configured by a relatively small number of pixels;

an imaging lens for forming an image of said light point at a position in front of the pixel array region of said image sensor;

a converging lens disposed between said image sensor and the position of the image of said light point on an optical axis of said imaging lens for converging light coming from said light point onto the pixel array region of said image sensor, the light passing through the image of said light point;

a transparent optical pattern plate having a pattern containing optical code information uniquely corresponding to the position of said light point on the screen, the plate being disposed between said converging lens and the position of the image of said light point in a plane parallel with the pixel array region of said image sensor, the code information pattern enabling the position of said light point to be determined by means of optical codes included in a region through which the light from said light point passes, said optical codes in the region being projected onto the pixel array region by the converging light coming from said light point onto the pixel array region; and

signal processing means for processing signals outputted from said image sensor on which said codes are projected onto said pixel array region so as to extract information of the position of said light point by using said codes.

2. The optical position detecting unit of claim 1 further comprising an optical mask disposed near said pattern plate for enabling only a portion of said pattern which contains said code information corresponding to the position of said light point to be incident on the image sensor.

3. The optical position detecting unit of claim 2 wherein said mask includes a variable position visual field for setting said portion of said pattern.

4. The optical position detecting unit of claim 2 wherein said mask is located at a position where the image of said light point is formed.

5. The optical position detecting unit of claim 1 wherein the pixels and pattern are arranged as two-dimensional arrays and said pattern has a two-dimensional M-sequence characteristic.

6. The optical position detecting unit of claim 5 wherein said pattern includes circular dot elements and ring-like dot elements arranged at each intersection of a lattice in a specific sequence.

7. Apparatus for detecting the position of a point optical image, comprising a screen surface from which the image is derived, an optical system located a predetermined distance from the screen surface and positioned to be responsive to the image, the optical system deriving an indication of the image position, and including:

an image sensor having a pixel array region configured by a relatively small number of pixels;

an imaging lens for forming an image of said light point at a position in front of the pixel array region of said image sensor;

a converging lens disposed between said image sensor and the position of the image of said light point on an optical axis of said imaging lens for converging light coming from said light point onto the pixel array region of said image sensor, the light passing through the image of said light point;

a transparent optical pattern plate having a pattern containing optical code information uniquely corresponding to the position of said light point on the screen, the plate being disposed between said converging lens and the position of the image of said light point in a plane parallel with the pixel array region of said image sensor, the code information pattern enabling the position of said light point to be determined by means of optical codes included in a region through which the light from said light point passes, said optical codes in the region being projected onto the pixel array region by the converging light coming from said light point onto the pixel array region;

the apparatus further including

signal processing means for processing signals outputted from said image sensor on which said codes are projected onto said pixel array region so as to extract information of the position of said light point by using said codes.

8. The apparatus of claim 7 further comprising an optical source for causing the point optical image to be derived from the screen, the optical source and the screen being spaced from each other so the screen responds to the source.

9. The apparatus of claim 7 further comprising an optical mask disposed near said pattern plate for enabling only a portion of said pattern which contains said code information corresponding to the position of said light point to be incident on the image sensor.

10. The apparatus of claim 8 wherein said mask includes a variable position visual field for setting said portion of said pattern.

11. The apparatus of claim 7 wherein said mask is located at a position where the image of said light point is formed.

12. The apparatus of claim 7 wherein the pixels and patterns are arranged as two-dimensional arrays and said pattern has a two-dimensional M-sequence characteristic.

13. The optical position detecting unit of claim 7 wherein said pattern includes circular dot elements and ring-like dot elements arranged at each intersection of a lattice in a specific sequence.

14. Apparatus for detecting the position of a point optical image on a surface, an optical beam being derived in response to the point optical image being incident on the surface, the optical beam having an axis and path intersecting the position on the surface where the point optical image is incident, the apparatus comprising an optical system remote from the surface for intercepting the beam, the optical system including an optical detecting surface in the beam path, and a transparent optical pattern including optically coded position identifying regions having positions uniquely corresponding to different positions of the point optical image on the surface from which the beam is derived, the pattern being positioned in the beam path between the optical detecting surface and the surface from which the beam is derived so the beam as incident on the optical detecting surface is modified in accordance with the optically coded regions in the beam path, the optical detecting surface causing derivation of a signal having values corresponding to the optically coded regions in the beam path.

15. The apparatus of claim 14 wherein the optical detecting surface is divided into pixels having a certain intercept area for the beam incident on the optical detecting surface, the pattern being such that there are several pixels in the beam path for each optically coded region in the beam path, a signal being derived from each pixel.

16. The apparatus of claim 15 further including a data processor responsive to the signal for deriving an indication of the location of a center of gravity of the point optical image as incident on the optical detecting surface.

17. The apparatus of claim 16 wherein the data processor, after deriving the a center of gravity of the point optical image as incident on the optical detecting surface, converts the signal corresponding to the optically coded regions in the beam path into the positions of the point optical image on the surface from which the beam is derived.

18. The apparatus of claim 17 further including a mask for selectively enabling optical energy from only a portion of the surface from which the point source image is derived to be incident on the optical detecting surface, the data processor controlling the mask position in response to the signal derived from the optical detecting surface.

19. The apparatus of claim 15 wherein the pixels and pattern are arranged as two-dimensional arrays.

20. The apparatus of claim 14 wherein the pattern has a two-dimensional M-sequence characteristic.

21. The apparatus of claim 20 wherein the pattern coded regions have different opacities.

22. The apparatus of claim 21 wherein one type of said regions is a circular dot having the same optical properties throughout its area and another type of said regions is a ring having the same outer diameter as the circular dot and different optical properties in its center and peripheral portions.

23. The apparatus of claim 22 wherein the rings and dots are arranged in a matrix of columns and rows.

24. The apparatus of claim 14 further including a mask for selectively enabling optical energy from only a portion of the surface from which the point source image is derived to be incident on the optical detecting surface, the mask position being controlled in response to the signal derived from the optical detecting surface.