JP3222205B2 - DMD analog scan converter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates generally to analog scan converters and, more particularly, to the use of deformable mirror devices (DMDs) to implement analog scan converters.

[0002]

BACKGROUND OF THE INVENTION While not intending to limit the scope of the present invention, its background will be described in connection with a system utilizing an IR sensor. Conventional devices that rely on linear IR sensors are being replaced by systems using multi-line sensors. These sensors have higher resolution and S /
The N-ratio aggregate increases accordingly, reducing the problems associated with aliasing. Usually, these sensors have only the required number of pixels to scan the vertical dimension of the scene due to the complexity of their manufacture. Scene data sent by shift from these vertical sensors is naturally in the form of a vertical raster. However, the human eye is used to seeing horizontal raster images. Accordingly, these sensors generally require a scan converter to recreate an IR image in the visible region for human viewing. A typical, high dynamic range digital scan converter to accomplish this task is expensive, bulky, heavy and consumes considerable power.

[0003] DMDs have several attractive features. The mirror element has a high reflectivity over a wide optical bandwidth. For this reason, light modulation from UV to IR can be performed.
The response time of a pixel is typically 10-20 μs, and the pixel can be operated in an analog or digital mode. A simple structural change of the mirror allows the DMD
Can act as either an amplitude-dominant or a phase-dominant modulator. DMDs can also be manufactured monolithically on top of low voltage, high density addressing circuits. Due to the low power consumption of DMDs, high frame rates (typically 5 kHz and above) are possible without the adverse effects of heating.

There are many DMD pixel structures, all designed for specific applications. They can be distinguished by deformation modes such as twisting or cantilever, pixel shape, and hinge support structure.

[0005]

SUMMARY OF THE INVENTION The present invention discloses a scan converter system (device) that receives at least one stream of serial input data from an input device, and serial to parallel connected to the shift register. And a DMD connected to a serial to parallel converter,
And a DMD that produces an illumination pattern substantially identical to the image received at the input device when the light source is reflected from the DMD. The DMD forms an image on the solid state detector, the detector is a CCD, the detector processes the image from the DMD, and outputs the image from the detector in a different order than when the image was input to the detector. It is preferable to be able to do this. Alternatively, the DMD forms an image on the backside of the scanning mirror and optically projects an image from the backside of the mirror to produce an image that is almost identical to the image received at the input device. Preferably, the DMD is a torsion beam DMD. Examples of input devices are IR sensors or computers. Preferably, the shift register, serial to parallel converter and DMD are in a monolithic integrated circuit.

The present invention is also a scan converter system, wherein at least one shift register receives at least one stream of serial input data from an input device, and at least one serial to parallel converter connected to the shift register. And at least one comparator whose input is connected to the output of the series-to-parallel converter and whose other input is connected to the lamp voltage, and at least one DMD which is connected to the comparator, wherein the light source from the DMD is Provide a DMD that, when reflected, produces an illumination pattern that is substantially identical to the image received at the input device.
The comparator is a ramp comparator, a shift register, a serial to parallel converter, a comparator and a DM.
D is preferably in a monolithic integrated circuit.

The present invention also discloses a method of forming a scan converter system, generally receiving at least one stream of serial input data from an input device, converting the serial data stream to parallel data, and converting the parallel data to a DMD. When the light source is reflected from the DMD, an illumination pattern substantially identical to the image received by the input device is created.

Reference will now be made to the drawings, wherein like numerals refer to like parts throughout the drawings, unless otherwise indicated.

[0009]

DETAILED DESCRIPTION OF THE INVENTION In a typical IR device (FIG. 1), an input image 10 is focused by a suitable optical system 24 onto the plane of an IR detector 12, which is configured as a row of discrete pixels. Of course, only one line of the image 10 can be detected at a predetermined time. Thus, one element of the imaging device is a mirror 14 pivotally mounted about its central axis, and by rotating the mirror 14 appropriately, any desired row of the image 10 is It can be focused.

The signal from each individual sensor element on the detector 12 is connected to a separate light emitting element (typically an LED) on the linear array 16. This array 16
The visible light emitted from the mirror is reflected by the back surface 18 of the scanning mirror 14, and an observer 20 looking at the back surface 18 of the mirror via a suitable optical system 22 makes it possible for the mirror 14 to view the scene 10 over the IR detector 12. As you scan, you see the input IR scene 10 play. Each individual connection path typically includes an amplifier, which adjusts offset and linearity to account for pixel-to-pixel sensitivity and emission variations in both the detector and the emitter. Can be done.

[0011] A high-end IR sensor is usually composed of a plurality of rows of pixel elements instead of a single row. With the addition of much more pixel elements to each detector, the number of output connections becomes very large. Such interconnects often cause reduced yields during manufacturing and failures in the field. Therefore, these high-end sensors often give up the serial shift register output for each column of pixels and abandon the parallel pixel outputs. Connecting such a serial output to an array of LEDs requires a complex arrangement, such as a monolithic LED board, which requires a serial-to-parallel converter or a separate serial-to-parallel converter chip. It requires a complex hybrid substrate with an array of many single row LEDs packaged on top of it. These types of cost-effective LED arrays are beyond current technology and require different types of displays. A typical solution, shown in FIG. 2, was to digitize multiple parallel or serial outputs 72 of a multi-line IR sensor 74 and store them in digital video memory 70. Thereafter, the video memory 70 is read out in series to drive the CRT display 76, or read out in parallel to drive a hybrid array of linear LED elements 78.

In the embodiment to be described, the twisting D
You can use MD. As shown in FIGS. 3 and 4, a twisted DMD pixel generally suspends a thick reflective beam 50 above the air gap / spacer 52 and provides a sturdy support by two tensioned thin twisted hinges 56. Alternatively, it is configured to be connected to the support layer 54. Address electrode 5 under beam 50
8 is energized, the twist hinge 56 twists and the beam 50
It rotates about the axis of one hinge 56 and rides on the landing electrode 60 below it. This structure is formed entirely on a substrate 62 of a material such as silicon. FIG. 4 shows some examples of hinges that can be used for twisted DMDs.

The first to the display problem of high-end IR devices
A solution according to a preferred embodiment of the invention is shown in FIG.
The DMD chip 28 has a chip structure of the IR sensor device 3.
The structure can be made to be substantially opposite to the structure of 0. Multiple analog serial shift registers 32 may be made on chip 28, or they may be external to the DMD chip, if desired. The number and length are matched to the number and length of the output shift registers in the IR sensor device 30. Each shift register 32 feeds, preferably via a serial-to-parallel converter 34, to as many DMD pixels 36 as come from the corresponding shift register in the IR device 30. Each DMD pixel 36 is connected to the input I (possibly except for the overall magnification).
An array similar to the array of pixels of the R device 30 can be used. Thus, a visible (or other wavelength) light source reflected from the DMD creates an illumination pattern that is almost identical to the incident on sensor 30 in the IR spectrum.

In a second preferred embodiment, the reconstructed image is projected onto the backside 18 of the scanning mirror 14 shown in FIG. 1 and can be viewed by reflection therefrom. The operation of a conventional IR device can be reproduced without the expense of either a digital scan converter or a complex LED assembly.

The intensity of the reflected image can be encoded in several ways. One method is analog modulation. If the output of the DMD analog shift register / serial to parallel converter 32,34 is connected directly to the address electrode below pixel 36, then each pixel 3
The deflection of 6 is proportional to the analog signal and therefore to the intensity of the input IR light. Using the degree of this slope of DMD,
It is common to perform analog light modulation by using dark field optics.

In a dark-field device, the DMD can be aligned such that the light reflected from the fully tilted DMD pixels falls completely within the aperture of the display optics. The optical system is designed with a limited opening so that the light reflected from the undeflected pixel completely exits the opening. Of course, at an intermediate position, the amount of light reflected by this optical aperture is also an intermediate amount, thus creating an intermediate level of brightness in the plane of the projected image.

Another method of encoding intensity is pulse width modulation. The accuracy with which an image is reconstructed based on analog modulation depends on the linearity and uniformity of the angle of inclination of the DMD pixels, as well as on the proper apodization of the projection optics. Using pulse width modulation with the dark field optics described above eliminates both of these problems.

In the third preferred embodiment shown in FIG. 6, instead of driving the DMD pixel 36 directly from the output of the shift register / serial to parallel converters 32, 34, a gradient comparison amplifier 38 (or the same). Any comparator-type circuit with function) can be placed between the output of each shift register / serial to parallel converter 32, 34 and the address electrode of the corresponding DMD 36.

At the end of each serial-to-parallel conversion, three things occur, as shown in FIG. The analog output of the shift register / serial to parallel converters 32, 34 (FIG. 6) is applied to one input 40 of the comparator at each DMD pixel 36 and the pixel at each pixel 36 is located. The drive amplifier 42 is switched on to drive each pixel 36 to a fully tilted position and the common voltage at the other input 44 of all comparators is detected from the lowest detectable shift register signal level. Start ramping to the highest possible shift register signal level.

The rate of this ramp causes the ramp to reach its maximum voltage when the scan line time is completed. This time is the time that the DMD pixel 36 is illuminated to display a single line on a CRT display. The output of the comparator 38 is connected to the input of the pixel drive amplifier 42 so that each comparator 3
8 toggles when the associated pixel drive amplifier 42
Is reduced to zero, causing the associated DMD pixel 36 to return to its skewed state. Thus, the length of time that a given pixel spends tilting during one scan line time (and thus the amount of light that pixel supplies to a display image during this scan line time) is determined from the shift register / serial. It is directly proportional to the voltage delivered to this pixel 36 by the converters 32,34 in parallel.

If one desires a separate display device (ie, a display device that does not rely on scanning performed by the back side of the input scanning mirror), any of these modulation schemes can be used to mimic the operation of a digital scan converter. Can be. As an example of the function of this scan converter, the DMD can be imaged on the top row of an area array CCD (or other solid state) detector. At the end of each scan line time, CC
The charge generated in D can be shifted down one row, in a manner similar to systole of the heart. The whole input image is CC
This order is advanced over the entire video frame time until stored in D. When this happens, the CCD can be read out directly to video on a CRT or other display device. DMDs can be imaged on a CCD in a variety of ways. Multiple DMDs and CCDs can be combined and their outputs manipulated electronically to accomplish complex optical processing tasks.

Conversely, a linear DMD modulator can be used to generate a display from an image stored, for example, in a CCD or digital frame memory. The serial analog data stream may have been retrieved directly from the CCD or from a frame memory via a digital-to-analog converter, but initially with an IR detector. Input to the analog shift register which is stated to be supplied from the device. After this, ordinary IR
The scanning mirror is driven in the same manner as the scanning mirror of the apparatus is driven, and the image projected line by line from the DMD is viewed by reflection from the mirror surface.

If digital data is readily available, or if digital operation is considered desirable,
It is easy to use DMD in digital mode. This digital mode requires the fabrication of a unique DMD similar in structure to that described above. N
For a digital data stream with bit resolution, create N input shift registers in the linear DMD. Each shift register represents a different resolution digital bit from the most significant bit to the least significant bit. Each shift register directly addresses its own row of DMD elements. The elements in each row are activated from the beginning of each scan line time. The most significant bit line is turned off in the middle of the scan line time, the next most significant is at 1/4 scan line time, and the third at 1/8.
Thus, each pixel in each row of the image is illuminated by N pixels, each illuminating for a period proportional to its weight in the binary sum. Thus, a total of N bits of binary optical amplitude is obtained.

This binary irradiation weight can be more easily realized by spatial weighting rather than temporal weighting. As previously mentioned, the N-bit binary data stream drives N input shift registers. However, in this scheme, each pixel along the shift register is spatially weighted. For example, in a device with 7-bit resolution, the most significant bit shift register drives 64 pixels at each DMD location. The next most significant bit drives 32 pixels. The next is to say 16 pieces. This method does not require a temporal resolution of less than scanline time, as it weights a predetermined percentage of the illumination by the percentage of available reflective area, rather than the percentage of available time. These two methods of binary illumination weighting (time and space) may be combined.
As a result, the resolution of the pixels is further increased due to the increased dynamic range of the combined method.

The DMD can be used to be a display in many different embodiments. The DMD can be configured to have the functionality of a scan converter with appropriate optics and reduced budget for size, weight, cost and power.
Further, the resulting DMD device can be displayed for viewing any stored digital image or analog data stream, regardless of its source.

A number of preferred embodiments have been described in detail. It is to be understood that the scope of the invention includes embodiments that differ from those described above, but which are also within the scope of the appended claims. For example, the input device is IR
Although described as a sensor, the input may come from many different sources, such as a television signal or a computer. Although dark-field optics have been described in connection with the use of this device, schlieren optics or other suitable optics can be used. Similarly, the image may be displayed directly using the DMD, or may be sent to another detector for manipulation prior to display. In interpreting the scope of the invention, it should be understood that the words used are not intended to be exhaustive.

Although the invention has been described with reference to an embodiment, this description should not be construed as limiting the invention.
From the above description, various modifications of the embodiments and other embodiments of the invention will be readily apparent to those skilled in the art. Therefore, it is to be understood that the appended claims are intended to cover such modifications or embodiments.

With respect to the above description, the following items are further disclosed. (1) At least one of serial input data from the input device
A shift register that receives two streams, a serial-to-parallel converter connected to the shift register, and a DMD connected to the serial-to-parallel converter, when a light source is reflected from the DMD. A DMD for producing an illumination pattern substantially identical to the image received by the input device.

(2) In the apparatus described in (1),
A device in which the detector processes the images from the DMD so that the images are output from the detector in a different order than when the images were input to the detector.

(3) At least one shift register for receiving at least one stream of serial input data from an input device, at least one serial-to-parallel converter connected to the shift register, and at least one comparator. The input of the comparator is connected to the output of the series-to-parallel converter and the other input is a comparator connected to a ramp voltage and at least one DMD connected to the comparator, wherein When the light source is reflected, an illumination pattern is created that is substantially identical to the image received by the input device.
D. a scan converter device comprising:

(4) In the apparatus described in (3),
The apparatus wherein the comparator is a ramp comparator.

(5) The apparatus according to the above (1) or (3), wherein the DMD forms an image on a solid state detector.

(6) In the apparatus described in the item (5),
A device in which the detector is a CCD.

(7) In the apparatus described in the item (5),
A device in which the detector processes the images from the DMD so that the images are output from the detector in a different order than when the images were input to the detector.

(8) In the apparatus described in the item (1) or (3), the DMD is a torsion beam DM.
A device that is D.

(9) The apparatus according to (3), wherein the DMD forms an image on the back side of the scanning mirror.

(10) An apparatus according to item (9), wherein an image from the back side of the mirror is optically projected to produce an image substantially identical to the image received by the input device.

(11) The apparatus according to the above mode (1) or (3), wherein the input device is an IR sensor.

(12) The apparatus according to the above (1) or (3), wherein the input device is a computer.

(13) The apparatus according to item (1) or (3), wherein the shift register, the serial-to-parallel converter, the comparator, and the DMD are provided in a monolithic integrated circuit.

(14) In a method of forming a scan converter device, receiving at least one stream of serial input data from an input device, converting the stream of serial data to parallel data, and sending the parallel data to a DMD. Generating an illumination pattern substantially identical to the image received at the input device when the light source is reflected from the DMD.

(15) The present invention discloses a scan converter system, comprising a shift register 32 for receiving at least one stream of serial input data from an input device 30, and a serial to parallel converter connected to the shift register 32. And a DMD 36 connected to a serial-to-parallel converter 34 that produces an illumination pattern substantially identical to the image received at the input device when the light source is reflected from the DMD.

(C) Copyright, * M * Texas Instruments Inc., 1991. Portions of the disclosure of this patent document include material that is subject to copyright and masking operations. The owner of the copyright and masking work shall not dispute that any patent document or patent disclosure may be reproduced by facsimile as long as it appears in the Patent and Trademark Office's patent file or record, but otherwise , Reserves all copyright and mask work rights in any form.

[Brief description of the drawings]

FIG. 1 is a diagram of a conventional IR image forming apparatus.

FIG. 2 is a block diagram of the electronic part of a high-end IR imaging apparatus.

FIG. 3 is a diagram of a twisted DMD.

FIG. 4 is a plan view showing examples of hinges of various twisted DMDs.

FIG. 5 is a diagram showing a first preferred embodiment of the present invention.

FIG. 6 illustrates a third preferred embodiment of the present invention using pulse width modulation.

FIG. 7 is a block diagram of a part of the device shown in FIG. 6;

[Explanation of symbols]

 28 DMD chip 30 IR sensor device 32 Shift register 34 Serial to parallel converter 36 DMD

Continuation of the front page (56) References JP-A-62-124518 (JP, A) JP-A-3-40693 (JP, A) JP-A-61-243480 (JP, A) US Patent 4,662,746 (US, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02B 26/08 G09G 3/34 H04N 5/335

Claims (1)

(57) [Claims] An input device for producing a data stream of multi-bit values, each value corresponding to a display intensity displayed at a display pixel, each of which being a multi-bit data stream from said input device. A plurality of shift registers having inputs coupled to receive data from corresponding bit positions of the D.D. and a binary weighted DMD array, wherein each D.D.
The MD is addressed by one of the associated shift registers and, in conjunction with the other associated DMDs corresponding to the other shift registers, produces the corresponding value in the data stream from the input device. A digitally modulated DMD system that reflects light from a light source in response to data from the corresponding shift register to illuminate the responded display pixel.