Method and apparatus for generating ratiometric control signals

• US 5,650,608 A
• Filed: 12/19/1994
• Issued: 07/22/1997
• Est. Priority Date: 12/05/1991
• Status: Expired due to Fees

• Current Assignee: TV Interactive Data Corporation
• Original Assignee: TV Interactive Data Corporation
• Inventors: Stern, Donald S., Redford, Peter M.
• Primary Examiner(s): ALLEN, STEPHONE B
• Application Number:
  US08/359,306
• Time in Patent Office: 946 Days
• Field of Search: 250/210, 250/208.2, 250/221, 250/239, 250/208.5, 356/222
• US Class Current: 250/210
• CPC Class Codes: A63F 13/213 comprising photodetecting means, e.g. cameras, photodiodes or infrared cells A63F13/219, A63F13/655 take precedence
• CPC Class Codes: A63F 13/24 Constructional details thereof, e.g. game controllers with detachable joystick handles
• CPC Class Codes: A63F 13/40 Processing input control signals of video game devices, e.g. signals generated by the player or derived from the environment
• CPC Class Codes: A63F 2300/1006 having additional degrees of freedom
• CPC Class Codes: A63F 2300/1037 being specially adapted for converting control signals received from the game device into a haptic signal, e.g. using force feedback
• CPC Class Codes: A63F 2300/1043 being characterized by constructional details
• CPC Class Codes: A63F 2300/1087 comprising photodetecting means, e.g. a camera
• CPC Class Codes: G01C 9/06 Electric or photoelectric indication or reading means
• CPC Class Codes: G01C 9/36 of the spherical type, i.e. for indicating the level in all directions
• CPC Class Codes: G01D 5/26 characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light
• CPC Class Codes: G05G 9/047 the controlling member being movable by hand about orthogonal axes, e.g. joysticks for switches H01H25/04
• CPC Class Codes: G06F 3/021 Arrangements integrating additional peripherals in a keyboard, e.g. card or barcode reader, optical scanner
• CPC Class Codes: G06F 3/0231 Cordless keyboards
• CPC Class Codes: G06F 3/033 Pointing devices displaced or positioned by the user , e.g. mice, trackballs, pens or joysticks; Accessories therefor digitisers characterised by the transducing means G06F3/041
• CPC Class Codes: G09B 9/04 for teaching control of land vehicles
• CPC Class Codes: G09B 9/28 Simulation of stick forces or the like
• CPC Class Codes: H01H 9/0235 specially adapted for remote control, e.g. of audio or video apparatus
• CPC Class Codes: H03F 3/08 controlled by light

Abstract

A ratiometric sensor is formed of a first photodiode connected in series with an electronic component, such as a second photodiode or a resistor, between a source of first voltage and a source of second voltage. The ratiometric sensor supplies a "ratiometric voltage" on a ratiometric sensor output line that is connected to a junction between the first photodiode and the electronic component. The ratiometric voltage is proportional to the ratio of the equivalent resistance of the first photodiode to the sum of the equivalent resistances of the first photodiode and the electronic component. A ratiometric sensor that uses a photodiode and a resistance has a large dynamic range because the ratiometric voltage can vary between the first voltage and the second voltage. A ratiometric sensor that uses two photodiodes is less sensitive to noise than a conventional circuit that uses a single photodiode, because noise can get canceled from the numerator and denominator of the ratio. The ratiometric signal can be digitized by an analog-to-digital converter that can include, for example, a 555 timer, a Darlington transistor or a combination of a resistor and a capacitor.

Claims

1. A circuit comprising:

a ratiometric sensor comprising a signal sensor, a first reference voltage line, a second reference voltage line and a ratiometric sensor output line,

said ratiometric sensor having a first equivalent resistance between said first reference voltage line and said ratiometric sensor output line,

said ratiometric sensor further having a second equivalent resistance between said second reference voltage line and said ratiometric sensor output line; and

a voltage controlled current amplifier consisting essentially of;

a pnp transistor having a base, a collector and an emitter, said base being coupled to said ratiometric sensor output line;

a first resistor coupled between said first reference voltage line and said emitter to thereby limit current supplied at said collector; and

a second resistor coupled between said first reference voltage line and said collector to thereby allow current to be supplied at said collector when said pnp transistor is off.

2. The circuit of claim 1 further comprising a Darlington pair wherein said pnp transistor is included in said Darlington pair.

3. The circuit of claim 1 comprising a plurality of ratiometric sensors for detection of movement along a plurality of axes.

4. The circuit of claim 1 wherein:

the first reference voltage line, the second reference voltage line and the collector are coupled to a game port of a personal computer.

5. The circuit of claim 1 wherein:

the ratiometric sensor comprises a potentiometer coupled between the first reference voltage line and the ratiometric sensor output line; and

the signal sensor is coupled between the second reference voltage line and the ratiometric sensor output line.

6. The circuit of claim 5 wherein the signal sensor comprises a photosensitive element.

7. The circuit of claim 6 wherein the photosensitive element is a photodiode.

8. The circuit of claim 7 wherein a cathode of the photodiode is coupled to the ratiometric sensor output line.

9. The circuit of claim 5 further comprising a light emitting diode, wherein the light emitting diode generates light incident on the photosensitive element.

10. The circuit of claim 9 wherein the light emitting diode has two terminals:

a first terminal coupled to the first reference voltage line; and

a second terminal coupled to the second reference voltage line.

11. The circuit of claim 1 wherein:

the ratiometric sensor comprises an electronic component coupled between the first reference voltage line and the ratiometric sensor output line; and

the signal sensor is coupled between the second reference voltage line and the ratiometric sensor output line.

12. The circuit of claim 11 wherein the signal sensor comprises a photosensitive element.

13. The circuit of claim 12 wherein the photosensitive element is a photodiode.

14. The circuit of claim 13 wherein a cathode of the photodiode is coupled to the ratiometric sensor output line.

15. The circuit of claim 12 further comprising a light emitting diode, wherein the light emitting diode generates light incident on the photosensitive element.