Monolithic optical autocompensation read-out circuit for distance dependent loudness control in mobile phones

• US 7,260,422 B2
• Filed: 02/10/2003
• Issued: 08/21/2007
• Est. Priority Date: 02/06/2003
• Status: Expired due to Fees

• Current Assignee: Dialog Semiconductor GmbH (Renesas Electronics Corporation)
• Original Assignee: Dialog Semiconductor GmbH (Renesas Electronics Corporation)
• Inventors: Knoedgen, Horst
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): Jackson, Blane J.
• Application Number:
  US10/361,876
• Publication Number:
  US 20040198463A1
• Time in Patent Office: 1,653 Days
• Field of Search: 455/200.1, 455/67.11, 455/268, 455/170.1, 455/219, 455/550.1, 455/569.1, 455/575.1, 455/574, 345/82, 345/704, 345/103, 345/156, 345/157, 725/133, 725/141
• US Class Current: 455/569.1
• CPC Class Codes: G01J 1/44 Electric circuits for command of an exposure part G03B7/02
• CPC Class Codes: H04M 1/605 involving control of the receiver volume to provide a dual operational mode at close or far distance from the user
• CPC Class Codes: H04M 2250/12 including a sensor for measuring a physical value, e.g. temperature or motion telephones including GPS signal receivers H04M2250/10
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A circuit and method are given, to realize a loudness control for mobile phone earpieces and speakers with the help of a proximity sensor, which is realized as an infrared photo-electric guard circuit, where only very few external parts are needed. As a novelty here, the necessary photo sensors are integrated onto a single chip. To form the photodiodes within a single IC together with the other circuit elements are much less expensive. Using the advantages of that solution the circuit of the invention is manufactured with standard CMOS technology and only very few discrete external components. This solution reduces also power consumption and manufacturing cost.

Claims

1. A method for realizing a loudness control of an earpiece of a mobile phone in such a way, that unpleasant and harmful loudness levels are avoided for the user by exploiting an optical proximity sensing method, consisting of a photon generating device and photon sensing devices with a common control means also used for the loudness control of a loudspeaker system, comprising:

providing said loudspeaker system of said earpiece, said photon generating device, said photon sensing device, and said common control means;

starting the driving of said sound generating loudspeaker system and establish a secure threshold sound level within said common control means;

setting-up and driving said photon-generating device as primary photon source;

establishing and operating two different photon-sensing devices in two different photo channels with basically identical channel characteristics but different spectral responses as determined by either a Photo Diode open to light or a Photo Diode dark or covered, said two different photo channels operating in parallel and commonly fed by said primary photon source and as such delivering a first and a second photo output signal;

measuring the distance from a reflective surface by comparing the photo output signals from said two different photo channels at two different periods in time;

evaluating said photo output signals from said two photo channels by continuously comparing said first and second photo output signals thus taking into account obnoxious side effects and thus effectively compensating for said obnoxious side effects;

comparing said measured distance to the correspondingly equivalent of said established secure sound level threshold value;

deciding accordingly to the programmed logic implemented within said common control means with its primary goal, to reduce loudness if distance of said earpiece to said user is small; and

generating output signals according to the result of the decision, thus avoiding unpleasant and harmful loudness levels.

2. The method according to claim 1 wherein said step of setting-up and driving said photon generating device as primary photon source is implemented as a driving of said photon source with pulses.

3. The method according to claim 1 wherein said step of establishing and driving two different photon sensing devices in two different photo channels is used for accounting of temperature drift effects and ambient light effects and where the driving signals for said different photo channels are synchronized pulses.

4. The method according to claim 1 wherein said photon generating device is implemented as a light emitting diode (LED).

5. The method according to claim 1 wherein said photon sensing devices are implemented as photo diodes.

6. The method according to claim 1 wherein said step of measuring the distance from a reflective surface by comparing said photo input signals to said two photo channels is realized as comparing said photo input signals from periods, where said photon generating device is operating (ON/light) and periods, where said photon generating device is not operating (OFF/dark).

7. The method according to claim 1 wherein said reflective surface is the head of a user.

8. The method according to claim 1 wherein said obnoxious side effects include any effects such as temperature and/or ageing drift and/or ambient light effects.

9. A circuit, capable of controlling the loudness of an earpiece of a phone or the like in such a way, that unpleasant and harmful loudness levels are avoided for the user of the earpiece by exploiting an optical proximity sensing method, comprising:

a means for generating photons having a photon control input and capable to serve as source for two different photo channels with basically identical channel characteristics;

a twin-pair of means for sensing photons generated by said means for generating photons and situated close to each other having a photon signal output for two photon output signals proportional to photonic intensity thus establishing said two different photo channels with basically identical channel characteristics but different spectral responses as determined by either a Photo Diode open to light or a Photo Diode dark or covered operating as correlated pair respectively in parallel;

a means for comparing said two photon output signals wherein continuously comparing the intensity of photons of said two different photo channels allows for compensation of obnoxious side effects and wherein measuring the intensity of said photons reflected from an object establishes said optical proximity sensing method thus determining the distance from circuit to object and generating a distance output signal at a photon signal output;

means for generating phonons having both a phonon signal and a phonon control input and wherein said phonon signal input receives external information signals additionally controlled by phonon control signals fed into said phonon control input by some means for common control of phonons and photons in such a way, that energy and intensity of the phonons are controlled subject to said distance output signal; and

said means for common control of phonons and photons controlling said means for generating photons, said means for sensing photons and said means for generating phonons having both phonon and photon control inputs and both phonon and photon control outputs wherein said phonon control input is fed from said phonon generating means and said photon control input is fed from said means for sensing photons and said photon control output is feeding said means for generating photons and said phonon control output is feeding said phonon generating means in such a way, that unpleasant and harmful loudness levels to the user are avoided.

10. The circuit according to claim 9 wherein said means for generating photons is a light emitting diode (LED).

11. The circuit according to claim 9 wherein said means for generating photons contains a driver circuit.

12. The circuit according to claim 9 wherein said means for sensing photons is a photo diode.

13. The circuit according to claim 9 wherein said means for sensing photons contains a photon receiver circuit.

14. The circuit according to claim 9 wherein said means for generating phonons is a loudspeaker in an earpiece.

15. The circuit according to claim 9 wherein said means for generating phonons contains an amplifier.

16. The circuit according to claim 9 wherein said means for common control is an integrated control circuit.

17. The circuit according to claim 9 manufactured in monolithic integrated circuit technology.

18. The circuit according to claim 9 wherein said object is the head of the user of the phone.

19. The circuit according to claim 17 manufactured in monolithic integrated CMOS technology.

20. The circuit according to claim 18 wherein said means for photon sensing is manufactured in N-well technology together with some kind of guard ring.

21. The circuit according to claim 18 wherein said means for photon sensing is manufactured in P-well technology together with some kind of guard ring.

22. The circuit according to claim 9 wherein said means for generating photons consists of more than one LED.

23. The circuit according to claim 9 wherein said means for comparing said two photon output signals is implemented as differential amplifier.