# US 9,039,207 B2 · Three dimensional image projector stabilization circuit

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- Number: US 9,039,207 B2
- Document ID: US9039207B2
- Status: Granted
- Kind: B2
- Application number: 13/672,947
- Filed: 2012-11-09
- Published: 2013-07-25
- Granted: 2015-05-26
- Earliest claimed: 2012-01-25
- Assignees: International Business Machines Corporation
- Applicants: International Business Machines Corporation
- Inventors: Casimer M. DeCusatis
- Web page: https://patentgrep.com/patent/US9039207B2

## CPC

- 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)}
- G03B 21/2073: {Polarisers in the lamp house (peculiar to electronic spatial light modulators H04N9/3197)}
- G03B 35/16: by sequential viewing
- G03B 35/26: using polarised or coloured light separating different viewpoint images
- H04N 13/337: using polarisation multiplexing
- G09G 2310/0286: Details of a shift registers arranged for use in a driving circuit
- H04N 13/363: using image projection screens (volumetric display H04N13/388)
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D)
- G09G: ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION (arrangements for transferring data between digital computers and displays G06F3/14; static indicating arrangements comprising an association of a number of separate sources or light control cells G09F9/00; static indicating arrangements comprising integral associations of a number of light sources H01J, H01K, H10H, H05B33/12; scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission, details thereof H04N1/00)

## Abstract

A method for providing a feedback circuit for a three dimensional projector. First and second input devices and a sensor for determining the rotational speed of the second input device are provided. A control device for controlling the rotational speed of the second input device and a phase locked loop (PLL) are provided. A phase reference signal is created based on the signal rate of the first input device. A phase signal is created based on the rotational speed of the second input device. The PLL compares the phase reference signal and the phase feedback signal to determine whether the first input device and the second input device are synchronized. A signal is sent to the control device for the second input device to change the rotational speed of the second input device in response to determining that the first input device and the second input device are not synchronized.

## Claims

### Claim 1

A method comprising:
providing a first input device;
providing a second input device;
providing a sensor for determining a rotational speed of the second input device;
providing a control device for the second input device, the control controlling the rotational speed of the second input device;
providing a phase locked loop (PLL);
creating a phase reference signal based on a signal rate of the first input device;
creating a phase feedback signal based on the rotational speed of the second input device as measured by the sensor;
comparing, by the PLL, the phase reference signal and the phase feedback signal to determine whether the first input device and the second input device are synchronized; and
sending, by the PLL, a signal to the control device for the second input device to change the rotational speed of the second input device responsive to determining that the first input device and the second input device are not synchronized.

### Claim 2 (depends on 1)

The method of claim 1, further comprising applying a programmable delay to the phase feedback signal prior to the comparing by the PLL.

### Claim 3 (depends on 1)

The method of claim 1, further comprising applying at least one of a signal conditioner and a signal amplifier the phase feedback signal prior to the comparing by the PLL.

### Claim 4 (depends on 1)

The method of claim 1, further comprising modifying the phase reference signal prior to the comparing by the PLL.

### Claim 5 (depends on 1)

The method of claim 1, wherein the first input device is an imaging device.

### Claim 6 (depends on 1)

The method of claim 1, wherein the first input device is a light source.

### Claim 7 (depends on 1)

The method of claim 1, wherein the second input device is a rotating polarizing beam splitter (PBS).

### Claim 8 (depends on 1)

The method of claim 1, wherein the second input device is a digital mirror device (DMD) comprising rotating mirrors.

### Claim 9 (depends on 1)

The method of claim 1, wherein the second input device is an imaging device.

### Claim 10 (depends on 1)

The method of claim 1, wherein the sensor is a tachometer.