Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
  • H04N25/70—SSIS architectures; Circuits associated therewith
  • H04N25/76—Addressed sensors, e.g. MOS or CMOS sensors
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
  • H04N25/70—SSIS architectures; Circuits associated therewith
  • H04N25/76—Addressed sensors, e.g. MOS or CMOS sensors
  • H04N25/767—Horizontal readout lines, multiplexers or registers
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
  • H04N25/70—SSIS architectures; Circuits associated therewith
  • H04N25/76—Addressed sensors, e.g. MOS or CMOS sensors
  • H04N25/779—Circuitry for scanning or addressing the pixel array

Definitions

• the present invention relates to improvements in electronic imaging and to solid state imaging apparatus in which the sensor component is designed to be read out at unusually fast frame rates.
• the use of solid-state area image sensors in video cameras has become increasingly popular in recent years. Such cameras are lighter, more compact and more reliable than their "tube-type" counterparts that use vidicons, orthicons or other electron tube devices for image sensing.
• the solid-state sensors presently available for use in video cameras provide acceptable resolution and are readable at the standard video frame rate of 30 frames per second.
• a typical solid-state area image sensor is comprised of an array of charge-integrating photosites (e.g., photocapacitors, photodiodes, etc.) arranged in rows and columns. Each photosite responds to incident radiation to provide, when appropriately addressed and read-out, a signal corresponding to the brightness of one picture element (pixel) of frame information.
• Such sensors are generally read out a line at a time, in a serial
• recording the motion of a rapidly moving object requires a frame rate high enough to "freeze” the object; if the object is not “frozen", successive frames will tend to smear into each other.
• the required frame rate depends, in general, upon the particular application and the amount of image smear that can be tolerated.
• frame rates as high as 2,000 frames per second, or more, are desired.
• One possible approach to obtaining faster frame rates from an area image sensor is to read out all sensor lines simultaneously, i.e., in parallel.
• parallel line readout With parallel line readout, the time required to read out a frame of information roughly corresponds to the time required to read out a single line since all lines are read out simultaneously.
• a significant drawback of the parallel line method of readout is that numerous individual "line" signals are produced that must be processed separately, but in a virtually identical manner. Such multi-signal processing is almost impossible (as a practical matter) in view of the fact that the levels of the signals to be processed may be quite low and the signals may have marginal signal-to-noise ratios.
• parallel line readout is generally limited to low resolution applications wherein only a relatively few lines of information are to be processed.
• an area image sensor is read out in "blocks" of photosites, each block being comprised of a plurality of adjacent photosite rows.
• a block of photosites is enabled for readout by the application of an enablement signal to all of the photosites within the block. All of the photosite rows in an "enabled” block are read out in parallel, that is, simultaneously, by sequentially applying address signals to the photosites in each row of the block.
• the output signal so produced is, therefore, comprised of block information in a "serial" format, while the information content of each block is comprised of a plurality of line signals in a "parallel” format, such line signals corresponding to the individual photosite rows within that block.
• a solid-state imaging apparatus comprising a sensor which is adapted to be read out according to the above-mentioned method of the invention.
• Such a sensor comprises an area array of photosites which are operatively connected to form a plurality of blocks, each block comprising a plurality of photosite rows which can be read out in parallel.
• Circuitry for sequentially enabling the individual blocks of photosites for readout, and for sequentially addressing the photosites of each row in a block, all rows in a block being addressed simultaneously, so that all photosite rows in a block are read out in parallel, and the plurality of photosite blocks are read out sequentially.
• Figs. 1 and 2 illustrate the block readout concept of the present invention
• Fig. 3 illustrates an area image sensor which is adapted for block readout in accordance with the invention
• Fig. 4 illustrates a color area image sensor which is adapted for block readout; and Figs. 5a and 5b illustrate other arrangements of photosite blocks which are considered within the scope of the invention.
• a technique for sensor readout in which the frame rate is increased dramatically over that obtainable with the above-mentioned serial line readout method. Moreover, such technique reduces the number of signals that must be identically processed to a fraction of the number resulting from the parallel line method of sensor readout.
• Fig. 1 shows a "monochromatic" area image sensor 40 (i.e., the photosites are sensitive to the same wavelength range of radiations) that is comprised of an array of photosites arranged in 192 horizontal rows R 1 -R 192 and 248 vertical columns C 1 - C 248 .
• a total of 47,616 i.e., 192 X 248) photosites, each being represented by the intersection of a row R and a column C in Fig. 1.
• Each photosite as discussed below in connection with the description of Fig. 3, is "readable” (i.e., adapated to provide a signal indicative of its illumination level) upon the application thereto of an enablement signal and an address signal.
• the photosites of sensor 40 are formatted into six blocks, B 1 , through B 6 , of 32 photosite rows each.
• a clock-driven driver circuit 22 (driven by clock 24) transmits a block start signal X to a conventional shift register 42 or similar circuit.
• shift register 42 Upon receipt of this start signal, shift register 42 produces a signal A which enables all 32 rows of block B 1 , for readout.
• column address electronics shown in the form of a column shift register 44, then sequentially addresses the photosite columns of the entire area image sensor 40 by sequentially providing address signals S 1 , S 2 , S 3 ,...S 248 . Since only the block B 1 , photosite rows (rows 1-32) have been enabled, however, only these rows of block 1 are actually read out.
• an "end of row” signal Y from the column shift register 44 causes the block select shift register 42 to terminate enable signal A and to transmit an enable signal B.
• enable signal B When enable signal B is present, only the block B 2 photosite rows are enabled, leaving all other blocks in a not-enabled state.
• Column readout then proceeds as described for the block B 1 photosite rows. This process is repeated until all six blocks of photosite rows are sequentially read out, at which time an "end of frame" signal Z from the block select shift register 42 resets the driver 22 for readout of the next frame.
• a multiplexer 45 which functions as a switch, reduces the number of active output lines from 192 to 32, the output signal S 0 appearing on the 32 active output lines corresponding to the 32 photosite rows being read out.
• the frame information produced as described immediately above is in neither the conventional parallel nor the conventional serial line format discussed previously.
• the block information is produced in series; and each block within the series contains 32 signals arranged in parallel which correspond to the photosite rows in the respective blocks.
• a 192-row sensor that can be read out at a maximum frame rate of, say 60 frames per second using the aforementioned serial line readout method can, by means of the above-described inventive format, be read at a rate of 1920 frames per second, i.e., 32 x 60.
• Fig. 2 illustrates, graphically, how frame information is formatted and recombined according to the invention to form a video display.
• a scene S imaged by an optical system 47 onto the area image sensor 40, is "sampled” by block enable pulses.
• the frame information F 1 corresponding to each block is shown in "pictorial form" directly above its respective block enable pulse.
• the blocks of information are recombined to form the complete playback video display V D .
• ⁇ is equal to the time required to read out each block.
• each photosite 50 includes two gates S1 and S2, each gate being part of a field effect transfer; (FET).
• Each gate S1 in a photosite row is connected to a common electrode for that row, in the form of a block select bus line 52, and all block select bus lines 52 of a block are connected in common to a single block enable bus line 53.
• the block select shift register 42 enables a block of pho.tosite rows for readout by applying an enablement signal to the block enable bus line 53, thereby setting each gate S1 within the enabled block to its closed state. All photosite rows in an enabled block are then column-wise read out simultaneously as the column shift register 44 sequentially addresses the photosite columns. As each column is addressed by signals S 1 , S 2 , S 3 ,...192, the gates S2 within the addressed column are closed, thereby causing signals from respective photosites which are both enabled and column-addressed to be applied to respective read channels 54 common to all photosites in the given rows.
• Fig. 4 shows a color area image sensor 40' of a type disclosed in U.S. Patent No. 4,117,510 wherein red, green and blue filters overlie respective rows of photosites.
• the red, green and blue (R,G,B, respectively) signals from photosite rows R 1 , R 2 and R 3 are read out simultaneously and combined to give one effective line of resolution L 1 of a scene imaged on the sensor.
• the red. green and blue signals from photosite rows 4, 5 and 6 are read out and combined to give a second effective line of resolution L 2 and so on for the remaining photosite rows.
• the time required for sensor readout can be greatly reduced.
• the sensor is divided, for purposes of readout, into four blocks B 1 , -B 4 , each block being comprised of two effective lines of resolution (six photosite rows) of a scene imaged on the sensor.
• sensor readout would take only one-half as long as the readout method taught in U.S. Patent No. 4,117,510.
• accelerated sensor readout is obtained by reading the sensor in blocks of photosites, wherein each block is comprised of a plurality of photosite rows that collectively represent two or more effective lines of resolution. For a three color system, such as described in connection with Fig.
• each block of photosites will be comprised of six or more photosite rows because fewer photosite rows per block will not represent at least two effective lines of resolution.
• the invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.
• the blocks of photosites need not be comprised of adjacent photosite rows but, rather, can be comprised of any plurality, of photosite rows.
• a block of photosite need not necessarily comprise rows of photosites which extend across the entire width of the array. Rather, the photosites of a block could be grouped as illustrated in Figs. 5a and 5b. In Fig.
• each block of photosites comprises a plurality of sub-rows of photosites, the number of sub-rows being equal to the number of photosites in an entire column.
• each block of photosites comprise contiguous sub-rows and sub-columns of photosites.
• the designated blocks of photosites are successively read out in a manner similar to that described above.
• a block can also take the form of a matrix of photosites, some or all of which photosites are not adjacently disposed.

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• Engineering & Computer Science (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Transforming Light Signals Into Electric Signals (AREA)
• Solid State Image Pick-Up Elements (AREA)
• Color Television Image Signal Generators (AREA)

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• 1980
  • 1980-01-16 US US06/112,483 patent/US4322752A/en not_active Expired - Lifetime
  • 1980-12-10 EP EP81900281A patent/EP0043828B1/en not_active Expired
  • 1980-12-10 WO PCT/US1980/001643 patent/WO1981002084A1/en not_active Ceased
  • 1980-12-10 JP JP81500502A patent/JPS56501704A/ja active Pending
  • 1980-12-10 DE DE8181900281T patent/DE3070821D1/de not_active Expired
  • 1980-12-29 CA CA000367604A patent/CA1157145A/en not_active Expired

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