Position transmitter for acquiring the position of a light beam

• US 5,444,234 A
• Filed: 09/26/1994
• Issued: 08/22/1995
• Est. Priority Date: 09/27/1993
• Status: Expired due to Fees

• Current Assignee: PerkinElmer Optoelectronics GmbH
• Original Assignee: Heimannn Optoelectronics GmbH
• Inventors: Brunst, Gerhard, Holzenkaempfer, Enno, Hennerici, Wolfgang
• Primary Examiner(s): Westin, Edward P.
• Assistant Examiner(s): Lee, John R.
• Application Number:
  US08/312,083
• Time in Patent Office: 330 Days
• Field of Search: 250/206.2, 250/206.1, 250/208.2, 250/208.3, 250/214.1, 250/203.1, 250/203.2, 250/203.3, 250/203.4, 250/203.6, 250/231.13, 250/231.14 , 250/231.18, 250/370.1, 356/141.5, 356/141.2, 356/141.3, 356/139.01, 257/443, 257/457, 257/459, 257/465
• US Class Current: 250/206.2
• CPC Class Codes: G01D 5/26 characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
• CPC Class Codes: H01L 27/1446 in a repetitive configuration

Abstract

A position transmitter for acquiring the position of a light beam has at least one group of photodiodes arranged neighboring one another and fashioned strip-shaped such that at least two, typically 5-10, strip-shaped electrodes of a photodiode structure are at least partially covered by the light beam or particle beam whose position is to be acquired. An evaluation circuit measures the photocurrent or a correlated quantity of the individual strip electrodes and indicates the position of the beam on the basis of the distribution of the strengths of the photo currents.

Claims

1. A position transmitter for acquiring the position of an electromagnetic beam comprising:

two groups of electrodes each composed of a plurality of strip-shaped photodiodes, the strip-shaped photodiodes in each group being parallel to the other strip-shaped photodiodes in that group, and the strip-shaped photodiodes in the two groups being perpendicular to each other, the strip-shaped photodiodes in each group being oriented so that at least two of the strip-shaped photodiodes in a group are at least partially covered by said beam, each strip-shaped photodiode generating a photocurrent corresponding to coverage of that strip-shaped photodiode by said beam; and

evaluation means for measuring the respective photocurrents and for identifying a position of said beam with reference to the distribution of the strengths of said photocurrents relative to the positions of the strip-shaped photodiodes in the groups.

2. A position transmitter as claimed in claim 1 wherein each of said strip-shaped photodiodes have an identical width and are disposed parallel to an immediately proximity with each other.

3. A position transmitter as claimed in claim 1 wherein said strip-shaped photodiodes in one of said groups are arranged in the form of a plurality of concentric circles.

4. A position transmitter as claimed in claim 3 wherein said strip-shaped photodiodes in the other of said groups of electrodes are disposed radially proceeding from a center of said concentric circles.

5. A position transmitter as claimed in claim 1 wherein said strip-shaped photodiodes comprise amorphous silicon applied onto a substrate of material selected from the group consisting of rigid glass, ceramic and metal.

6. A position transmitter as claimed in claim 5 wherein said strip-shaped photodiodes comprise Schottky diodes.

7. A position transmitter as claimed in claim 5 wherein said strip-shaped photodiodes comprise PIN diodes.

8. A position transmitter as claimed in claim 1 wherein said strip-shaped photodiodes are photolithographically applied on foil material.

9. A position transmitter as claimed in claim 1 wherein said strip-shaped photodiodes comprise crystalline silicon photodiodes.

10. A position transmitter as claimed in claim 1 wherein said evaluation means comprises a plurality of resistors respectively allocated to said strip-shaped photodiodes, and means for measuring a voltage drop of said photocurrent across each resistor.

11. A position transmitter as claimed in claim 1 wherein said strip-shaped photodiodes comprise amorphous silicon photodiodes, and wherein said evaluation means comprise a plurality of integrated thin-film transistors respectively connected to said strip-shaped photodiodes and means for reading signals from said transistors.

12. A position transmitter as claimed in claim 11 wherein said means for reading operates at a switching frequency and includes a further thin-film transistor for increasing said switching frequency.

13. A position transmitter as claimed in claim 11 wherein said thin-film transistors are identically constructed, and wherein said means for reading includes means for addressing said thin-film transistors with a pair of address signals composed of a binary coded address and a negated address complementary to said binary coded address.

14. A position transmitter as claimed in claim 1 wherein said evaluation means includes means for employing a curve matching method for identifying said position of said radiation beam by said distribution of the strengths of said photocurrents.

15. A position transmitter as claimed in claim 1 wherein each strip-shaped photodiode comprises first and second regions separated along a direction perpendicular to their width, said first region having a width corresponding to a number of said strip-shaped photodiode within its group with said width increasing according to said number, and the other region in each electrode having a width so that a combined width of said first and second regions is the same for each strip-shaped photodiode;

and

said evaluation means including a first contact electrically connected to each of said first regions and a second contact connected to each of said second regions, and means for calculating a sum of said photocurrents weighted by the number of the strip-shaped photodiode within the group and for identifying a centroid of said distribution of the strengths of said photocurrents from a difference between signals at said first contact and said second contact.

16. A position transmitter as claimed in claim 1 wherein each strip-shaped photodiode comprises first and second regions separated along a direction perpendicular to their resistance, said first region having a resistance corresponding to a number of said strip-shaped photodiode within its group with said resistance increasing according to said number, and the other region in each electrode having a resistance so that a combined resistance of said first and second regions is the same for each strip-shaped photodiode;

and

said evaluation means including a first contact electrically connected to each of said first regions and a second contact connected to each of said second regions, and means for calculating a sum of said photocurrents weighted by the number of the strip-shaped photodiode within the group and for identifying a centroid of said distribution of the strengths of said photocurrents from a difference between signals at said first contact and said second contact.