IMAGE PROJECTION APPARATUS, MEMORY CONTROL APPARATUS, LASER PROJECTOR, AND MEMORY ACCESS METHOD

• US 20120127184A1
• Filed: 11/14/2011
• Published: 05/24/2012
• Est. Priority Date: 11/19/2010
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: SATOH, Tetsuya, Yamamoto, Hideaki, Saisho, Kenichiroh
• Granted Patent: US 8,884,975 B2
• Time in Patent Office: Days
• US Class Current: 345/530
• 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 9/3185 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
• CPC Class Codes: H04N 9/3197 using light modulating optical valves

Abstract

An image projection apparatus includes an input part that inputs image data, a frame memory that stores the image data, a laser oscillator that radiates a laser to a screen, a deflection part including a reflective optical element and configured to oscillate the reflective optical element with respect to two perpendicularly intersecting axes, a storage part that stores coefficient data of a polynomial expression, an irradiation position calculating part that calculates an irradiation position based on a coefficient obtained by using the coefficient data and an oscillation angle of the reflective optical element, an address calculating part that calculates an address in the frame memory corresponding to the irradiation position, a memory control part that reads out pixel data of the address, and a laser drive part that oscillates the laser oscillator in accordance with a luminance corresponding to the pixel data.

Claims

1. An image projection apparatus comprising:

an input part configured to input image data;

a frame memory configured to store the image data;

a laser oscillator configured to radiate a laser to a screen;

a deflection part including a reflective optical element and configured to oscillate the reflective optical element with respect to two perpendicularly intersecting axes;

a storage part configured to store coefficient data of a polynomial expression;

an irradiation position calculating part configured to calculate an irradiation position based on a coefficient obtained by using the coefficient data and an oscillation angle of the reflective optical element;

an address calculating part configured to calculate an address in the frame memory corresponding to the irradiation position;

a memory control part configured to read out pixel data of the address; and

a laser drive part configured to oscillate the laser oscillator in accordance with a luminance corresponding to the pixel data.

2. The image projection apparatus as claimed in claim 1, further comprising a determination table;

wherein the address calculating part is configured to determine whether the irradiation position is within at least one of a rectangle maintaining an aspect ratio of the image data or a predetermined rectangle by referring to the determination table;

wherein the address calculating part is configured to output blank data corresponding to a pixel having a luminance of a black level in a case where the address calculating part determines that the irradiation position is not within the rectangle maintaining the aspect ratio of the image data or the predetermined rectangle.

3. The image projection apparatus as claimed in claim 2, wherein the address calculating part is configured to calculate the address in the frame memory corresponding to the irradiation position in a case where the address calculating part determines that the irradiation position is within the rectangle maintaining the aspect ratio of the image data or the predetermined rectangle.

4. The image projection apparatus as claimed in claim 2, further comprising a conversion table including coordinate positions inside the rectangle maintaining the aspect ratio of the image data or the predetermined rectangle;

wherein the address calculating part is configured to convert the irradiation position to one of the coordinate positions and calculate the address in the frame memory based on the converted irradiation position in a case where the address calculating part determines that the irradiation position is within the rectangle maintaining the aspect ratio of the image data or the predetermined rectangle.

5. The image projection apparatus as claimed in claim 1,

wherein the reflective optical element is configured to oscillate in a first direction and a second direction that perpendicularly intersects with the first direction;

wherein the polynomial expression includes a first polynomial expression that approximates the irradiation position when scanning the reflective optical element in the second direction in a case where the oscillation angle in the first direction is fixed and a second polynomial expression that approximates the irradiation position when scanning the reflective optical element in the first direction in a case where the oscillation angle in the second direction is fixed.

6. The image projection apparatus as claimed in claim 5, wherein the first polynomial expression is a primary polynomial expression with respect to a vertical angle and the second polynomial expression is a secondary polynomial expression with respect to a horizontal direction.

7. The image projection apparatus as claimed in claim 6,

wherein the irradiation position calculating part is configured to calculate the coefficient with respect to a vertical angle by applying the coefficient data with respect to a secondary approximation expression with respect to the vertical angle;

wherein the irradiation position calculating part is configured to calculate the coefficient with respect to a horizontal angle by applying the coefficient data with respect to another secondary approximation expression with respect to the horizontal angle.

8. A memory control apparatus comprising:

an input buffer configured to temporarily store image data and write the image data to a frame memory;

an address generating part configured to generate a readout address;

a determining part configured to determine whether there are consecutive requests to read out the image data from the same address in the frame memory and determine whether there is a request to read the image data corresponding to a blank address by referring to the address generating part;

a readout instructing part configured to instruct the frame memory to output the image data in a case where the determining part determines that there are no consecutive requests to read out the image data and no request to read the image data corresponding to the blank address;

a data obtaining part configured to obtain the image data from the frame memory; and

a data reproducing part configured to reproduce the image data consecutively requested to be read out and blank image data corresponding to the blank address.

9. The memory control apparatus as claimed in claim 8,

wherein the determining part is configured to count the number of times of the consecutive requests and report the number of times to the data reproducing part;

wherein the data reproducing part is configured to duplicate the image data consecutively requested to be read out in accordance with the number of times until the determining part determines that there are no consecutive requests to read out the image data.

10. The memory control apparatus as claimed in claim 8,

wherein the determining part is configured to count the number of times of the request to read the image data corresponding to the blank address and report the number of times to the data reproducing part;

wherein the data reproducing part is configured to duplicate the blank image data corresponding to the blank address in accordance with the number of times.

11. The memory control apparatus as claimed in claim 8, further comprising:

an output buffer configured to temporarily store the image data obtained by the data obtaining part and the image data reproduced by the data reproducing part; and

an arbitrating part configured to arbitrate a writing request from the input buffer and a readout request from the output buffer by obtaining flags from the input and the output buffers for writing the image data consecutively to the frame memory and reading out the image data from the frame memory.

12. The memory control apparatus as claimed in claim 11, wherein the arbitrating part is configured to arbitrate the writing request and the readout request for consecutively writing the image data until a half or more of a storage capacity of the output buffer is filled and for consecutively reading out the image data until the input buffer becomes empty.

13. The memory control apparatus as claimed in claim 8, wherein the determining part is configured to determine that there are consecutive requests to read out the image data from the same address in the frame memory when an address prior to a current address generated by the address generating part is the blank address or when at least one of the current address or the address prior to the current address is not the blank address.

14. The memory control apparatus as claimed in claim 9, wherein the readout instructing part configured to instruct the frame memory to output the image data in a case where the number of times of the consecutive requests is equal to or greater than a predetermined number of times.

15. A laser projector comprising:

the memory control apparatus as claimed in claim 8;

a frame memory configured to write and readout image data faster in a case of consecutive access compared to non-consecutive access; and

an optical engine including a laser oscillator, a resonance type MEMS (Micro-Electro-Mechanical-System) mirror.

16. A memory access method comprising the steps of:

temporarily storing image data;

writing the image data to a frame memory;

generating a readout address;

determining whether there are consecutive requests to read out the image data from the same address in the frame memory and determine whether there is a request to read the image data corresponding to a blank address by referring to the generating step;

instructing the frame memory to output the image data in a case where the determining part determines that there are no consecutive requests to read out the image data and no request to read the image data corresponding to the blank address;

obtaining the image data from the frame memory; and

reproducing the image data consecutively requested to be read out and blank image data corresponding to the blank address.