Stabilized pico-projector device and related image stabilization method

• US 9,383,591 B2
• Filed: 08/26/2013
• Issued: 07/05/2016
• Est. Priority Date: 08/31/2012
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: Pasolini, Fabio
• Primary Examiner(s): Dowling, William C
• Assistant Examiner(s): Howard, Ryan
• Application Number:
  US13/975,429
• Publication Number:
  US 20140063473A1
• Time in Patent Office: 1,044 Days
• Field of Search: 353/69, 353/70, 353/98, 353/99
• US Class Current: 1/1
• CPC Class Codes: G02B 27/646 compensating for small deviations, e.g. due to vibration or shake movement of one or more optical elements for control of motion blur in cameras, projectors or printers G03B2205/0007; image stabilisation in cameras peculiar to the presence or use of an electronic image sensor H04N23/68
• CPC Class Codes: G03B 21/142 Adjusting of projection optics
• CPC Class Codes: G03B 21/28 Reflectors in projection beam in illumination beam G03B21/2066
• CPC Class Codes: H04N 9/312 Driving therefor driving of electronic spatial light modulators in displays other than projection devices G09G3/34, G09G3/36; control of liquid crystal elements G02F1/133; control of micromechanical modulators G02B26/08
• CPC Class Codes: H04N 9/3129 scanning a light beam on the display screen scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161
• CPC Class Codes: H04N 9/3173 wherein the projection device is specially adapted for enhanced portability
• CPC Class Codes: H04N 9/3185 Geometric adjustment, e.g. keystone or convergence optical or mechanical adjustment of convergence H04N9/317; using scanning means H04N3/22; optical or mechanical adjustments of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/14

Abstract

A pico-projector device includes a light source operable to generate a light beam as a function of an image to be generated, a mirror mechanism operable to direct the light beam towards a displaying surface, and a driving circuit that supplies driving signals for controlling movement of the mirror mechanism. The driving circuit includes a compensation stage that receives angular velocity signals from a gyroscopic sensor coupled to the pico-projector device and generates the driving signals as a function of the angular velocity signals, thereby stabilizing the image projected on the displaying surface with respect to undesired movements of the pico-projector device.

Claims

1. A pico-projector device, comprising:

a light source operable to generate a light beam as a function of an image to be generated;

a mirror mechanism operable to direct the light beam towards a displaying surface; and

a driving circuit configured to supply driving signals for movement of said mirror mechanism, said driving circuit further comprising;

a generator stage for receiving an image array and generating control signals; and

a compensation stage configured to receive angular velocity signals from a gyroscopic sensor coupled to said pico-projector device, and to generate compensation signals by multiplication of the angular velocity signals with a corrective factor, and to subtract the compensation signals from the control signals to generate said driving signals for stabilizing the image projected on said displaying surface with respect to undesired movements of said pico-projector device.

2. The device according to claim 1, wherein said generator stage is configured to generate the control signals for said mirror mechanism as a function of said image to be generated and of a desired scanning path on said displaying surface.

3. The device according to claim 1, wherein said compensation stage comprises:

a processing unit configured to filter said angular velocity signals so as to remove components of the angular velocity signals relating to desired movements of said pico-projector device and leave components relating to said undesired movements of said pico-projector device for generation of said compensation signals.

4. The device according to claim 2, wherein said mirror mechanism is operable to perform horizontal scanning and vertical scanning movements with respect to said displaying surface as a function of respective driving signals;

and wherein said compensation signals include a first compensation signal generated as a function of a yaw angular velocity and/or of a roll angular velocity, designed to compensate undesired movements regarding said horizontal scanning movement; and

a second compensation signal generated as a function of a pitch angular velocity, designed to compensate undesired movements regarding said vertical scanning movement.

5. The device according to claim 4, wherein said mirror mechanism is of a MEMS type and comprises a first mirror operable for performing said horizontal scanning movement;

and a second mirror operable for performing said vertical scanning movement.

6. The device according to claim 1, wherein said undesired movements are due to vibrations from the external environment.

7. The device according to claim 1, including, in an integrated manner, said gyroscopic sensor.

8. The device according to claim 1, wherein the light source, mirror mechanism and driving circuit are provided within a portable electronic apparatus.

9. The device according to claim 1, wherein the light source, mirror mechanism and driving circuit are provided within an accessory device having a casing releasably coupled to a respective casing of a portable electronic apparatus.

10. The device according to claim 1, wherein the light source, mirror mechanism and driving circuit are provided in an integrated manner inside a casing of a portable electronic apparatus.

11. The device of claim 8, wherein the portable apparatus is selected from the group consisting of:

a mobile phone;

a smartphone;

a PDA;

a tablet;

a digital audio player;

a controller for videogames.

12. An image stabilization method, comprising:

generating control signals for projecting an image with a light beam towards a displaying surface;

receiving angular velocity signals from a gyroscopic sensor coupled to a pico-projector device having a light source operable to generate the light beam;

applying a corrective factor to the angular velocity signals to generate compensation signals; and

generating driving signals for controlling movement of said mirror mechanism by subtracting the compensation signals from the control signals thereby stabilizing the image projected on said displaying surface with respect to undesired movements of said pico-projector device.

13. The method according to claim 12, further comprising filtering said angular velocity signals so as to remove components of the angular velocity signals relating to desired movements of said pico-projector device and leave components relating to said undesired movements of said pico-projector device.

14. A projector device, comprising:

a gyroscopic sensor configured to generate angular velocity signals indicative of both desired movements of the projector device and undesired movements of the projector device;

a light source configured to generate a light beam;

a movable mirror configured to direct the light beam;

a mirror drive circuit configured to control movement of the movable mirror using drive signals; and

a compensation circuit within the mirror drive circuit that receives the angular velocity signals and filters the angular velocity signals to discriminate the undesired movements from the desired movements, generate correction signals by multiplication of the angular velocity signals for the undesired movements with a corrective factor and generate said drive signals by subtracting the correction signals from control signals related to an image.

15. The device according to claim 14, wherein the control signals are generated in the mirror drive circuit including a generator stage configured to generate the control signals for controlling movement of the moveable mirror as a function of the image to be generated.