1. Field of the Invention
The present invention relates to an imaging apparatus and an imaging system capable of outputting, as image information, an electrical signal that has been photoelectrically converted from a pixel optionally designated as a target to be read from among a plurality of pixels to be imaged, for example.
2. Description of the Related Art
In the medical field, an endoscope system is used for observing an organ of a subject such as a patient in the related art. The endoscope system includes: an inserting portion which is flexible, has a long thin shape, and configured to be inserted into a body cavity of the subject; an image pickup device (imaging apparatus) provided at a distal end of the inserting portion and configured to capture an in-vivo image; and a display unit capable of displaying the in-vivo image captured by the image pickup device. At the time of acquiring the in-vivo image by using the endoscope system, the inserting portion is inserted into the body cavity of the subject, and then an illuminating light such as a white light is emitted to a body tissue inside the body cavity from the distal end of the inserting portion, and the image pickup device captures the in-vivo image. A user such as a doctor observes the organ of the subject based on the in-vivo image displayed by the display unit.
In the pixel P100 having the above-described configuration, when a reset pulse φRSP becomes high level (rises), the reset transistor RS-TR100 is controlled to be turned ON and the capacitor FD100 is reset. After that, the signal electric charge corresponding to the incident light quantity is sequentially accumulated in the photodiode PD100. Here, when the transfer transistor T-TR100 is controlled to be turned ON (when the electric charge transfer pulse φTR rises) in the pixel P100 to be read out from the light receiving unit, transfer of the signal electric charge from the photodiode PD100 to the capacitor FD100 is started. Also, the row selection transistor S-TR100 is controlled to be turned ON by the row selection pulse φSE from the vertical scanning circuit VC100 (row selection circuit), thereby outputting pixel information (signal electric charge of the photodiode PD100) of each line to the reading unit as a pixel signal in the order of reading. Further, in accordance with this pixel signal output, a pixel output voltage Vpout changes from a reset level to a video level.
Thus, signal processing such as noise reduction by use of, for example, Correlated Double Sampling is applied to the image signal from each pixel P100, and then the image signal is output to the outside as an output voltage Vcout. At this point, a signal processing unit executing the signal processing outputs a video signal at a voltage level between a maximum (max) and a minimum (min) (see
In the case where malfunction occurs in the endoscope system having the above-described image pickup device, it is necessary to identify a failure location. Here, in the case where abnormality is occurring in a displayed image, at which component (inserting portion, imaging apparatus, and display unit) the failure is occurring can be determined by replacing each component with other so as to identify the failure location from among the above-described inserting portion, imaging apparatus, and display unit.
In Addition, for example, Japanese Patent Application Laid-open No. 2011-206185 discloses a technique in which a test pattern signal for detecting abnormality of a signal or the like is generated from an imaging apparatus as a tool to identify the abnormality occurrence on the imaging apparatus side, and an image based on this test pattern signal is displayed by a display unit, thereby identifying the failure location. Further, for example, Japanese Patent Application Laid-open No. 2009-226169 discloses a technology in which presence of a missing bit in digital signal data is determined at an imaging apparatus and it is determined whether abnormality in the imaging apparatus is caused by malfunction of a CCD, or malfunction of an AFE (analog front end) that performs analog-digital conversion, etc. on the data. Moreover, for example, Japanese Patent Application Laid-open No. 2011-55543 discloses a technology in which presence of abnormality is determined based on a test pattern signal and in the case where there is abnormality occurring, correction processing for data to be transmitted is executed.
An imaging apparatus according to one aspect of the invention includes: a sensor unit having a light receiving unit provided with a plurality of pixels for photoelectrically converting received light to generate an electrical signal after photoelectric conversion, and capable of reading the electrical signal generated by the light receiving unit as image information; a control unit configured to control an output mode of the electrical signal on a pixel-by-pixel basis such that a pixel signal level generated by photoelectrically converting the light and a reset level of the pixels are alternately output, and configured to output the electrical signal corresponding to a specified display pattern; a signal processing unit configured to perform signal processing on the electrical signal output from the sensor unit; and a transmission unit configured to transmit a processed signal processed by the signal processing unit to outside.
An imaging system according to another aspect of the invention includes: an imaging apparatus including: a sensor unit having a light receiving unit provided with a plurality of pixels for photoelectrically converting received light to generate an electrical signal after photoelectric conversion, and capable of reading the electrical signal generated by the light receiving unit as image information; a control unit configured to control an output mode of the electrical signal on a pixel-by-pixel basis such that a pixel signal level generated by photoelectrically converting the light and a reset level of the pixels are alternately output, and configured to output the electrical signal corresponding to a specified display pattern; a signal processing unit configured to perform signal processing on the electrical signal output from the sensor unit; and a transmission unit configured to transmit a processed signal processed by the signal processing unit to outside; and a processing device electrically connected to the imaging apparatus and configured to generate image data based on the processed signal transmitted from the transmission unit.
The above and other features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings.
As modes for carrying out the invention (hereinafter, referred to as “embodiments”), a medical endoscope system that captures and displays an image inside a body cavity of a subject such as a patient will be described below as an example of an imaging system. Also, note that the present invention is not limited to the embodiments. Further, note that the same components are denoted by the same reference signs in the drawings. Furthermore, note that the drawings are schematic and the relation of the thicknesses and the widths of the respective members, the ratio of the respective members, etc. differ from the actual relation. Portions that have different sizes and ratios one another may be included among the drawings.
The endoscope 2 is connected to an inserting portion 21 having flexibility and a thin long shape and also to a proximal-end side of the inserting portion 21, and includes an operating unit 22 that receives various kinds of operation signals, and a universal cord 23 that extends in a direction different from a direction in which the inserting portion 21 extends from the operating unit 22 and includes various kinds of cables that connect the control device 3 to the light source device 4.
The inserting portion 21 includes a distal-end portion 24 including an image pickup device later described inside thereof, a freely-bendable bending portion 25 including a plurality of bending pieces, and a long-shaped flexible tube 26 connected to a proximal-end side of the bending portion 25.
The distal-end portion 24 includes: a light guide 241 formed of glass fiber and the like and constituting a guide optical path for the light generated from the light source device 4; an illumination lens 242 provided at a distal end of the light guide 241; an optical system 243 for condensing the light, an image pickup device 244 as an imaging apparatus provided at an image forming position of the optical system 243 and configured to receive the light condensed by the optical system 243, photoelectrically convert the light to an electrical signal, and apply a prescribed signal processing to the electrical signal; a cable assembly 245; and an instrument channel (not shown) where the instrument of the endoscope 2 passes through. The optical system 243 includes one or a plurality of lenses.
The configuration of the image pickup device 244 will be described with reference to
The sensor unit 244a includes a light receiving unit 244f on which photodiode that accumulates electric charge corresponding to a light quantity and a plurality of pixels that outputs the electric charge accumulated by the photodiode are arranged in a two-dimensional matrix form, and a reading unit 244g that reads, as the image information, an electrical signal generated by a pixel optionally set as a reading target from among the plurality of pixels of the light receiving unit 244f.
The AFE unit 244b includes a noise reduction unit 244h that reduces noise components contained in the electrical signal, an AGC (Auto Gain Control) unit 244i that adjusts a gain of the electrical signal to keep a constant output level as an adjustment unit, and an A/D converter 244j that performs analog-digital conversion on the electrical signal output via the AGC unit 244i. The noise reduction unit 244h reduces noise by using, for example, correlated double sampling.
The control unit 244e controls various kinds of operations of the distal-end portion 24 in accordance with setting data received from the control device 3. The control unit 244e is formed by using a CPU (Central Processing Unit) or the like. Further, the control unit 244e controls the output mode of the electrical signals output by the respective pixels of the light receiving unit 244f per pixel unit based on address information related to a reading target pixel set by a reading address setting unit 305 described later, and controls the reading unit 244g to output an electrical signal corresponding to a prescribed display pattern (test pattern).
The storage unit 244k is implemented by using a semiconductor memory such as a flash memory or a DRAM (Dynamic Random Access Memory), and stores identification information of the control device 3, observation information indicating that an observation method is a simultaneous method or a frame sequential method, an imaging speed (frame rate) of the image pickup device 244, setting information such as a pixel information reading speed of the sensor unit 244a from an optional pixel and a shutter control setting, transmission control information of the pixel information read by the AFE unit 244b, pattern information of a test pattern signal (electrical signal corresponding to a prescribed display pattern) so as to identify an abnormality location, and so on. Note that the test pattern signal includes an electrical signal corresponding to a pseudo video signal.
The cable assembly 245 in which a plurality of signal lines for transmitting and receiving the electrical signal to and from the control device 3 is bundled is connected between the operating unit 22 and the distal-end portion 24, and the cable assembly 224 is connected between the operating unit 22 and a connector portion 27. The plurality of signal lines includes a signal line to transmit an image signal output from the image pickup device 244 to the control device 3, a signal line to transmit a control signal output from the control device 3 to the image pickup device 244, and so on. Further, for transmitting/receiving the electrical signal, a transmission method (differential transmission) whereby two signal lines (differential signal lines) are used to transmit one signal is adopted. Since noise can be cancelled by setting voltages of the differential signal lines to positive (+) and negative (−, phase inversion) even when the noise is mixed, resistivity against noise is higher compared to a single end signal and therefore high-speed data transmission can be achieved, suppressing radiation noise. The above-described differential transmission is preferably used in the case where the length of the universal cord 23 or the flexible tube 26 is long. In the case where the mentioned length is short, single end signal transmission utilizing the single end signal can be adopted.
The operating unit 22 includes a bending knob 221 that bends the bending portion 25 in the vertical direction and in the horizontal direction, a treatment instrument inserting portion 222 from which a treatment instrument such as a living body forceps, a laser knife, an inspection probe or the like is inserted into the body cavity, and a plurality of switches 223 that functions as an operation input unit that inputs operation instruction signals of peripheral devices such as an air feed means, a water feed means, a gas feed means besides the control device 3 and the light source device 4. The instrument to be inserted from the instrument inserting portion 222 passes through the instrument channel of the distal-end portion 24 and is exposed from an aperture (not shown).
The universal cord 23 includes at least the light guide 241 and the cable assembly 224.
Further, the endoscope 2 is disposed at an end of a side different from a side connected to the operating unit 22 of the universal cord 23, and includes the connector portion 27 detachably attached to each of the control device 3 and the light source device 4. At the connector portion 27, the connecting part detachably connected to each of the control device 3 and the light source device 4 is electrically connected via a coil-like coil cable. The connector portion 27 includes, inside thereof, a control unit 271 that controls the endoscope 2, an FPGA (Field Programmable Gate Array) 272, a reference clock generation unit 273 that generates a reference clock signal (e.g., 68 MHz clock) to be a basis of operation in each of the components inside the endoscope 2, a first EEPROM 274 that records configuration data of the FPGA 272, and a second EEPROM 275 that stores individual data of the endoscope including imaging information. The connector portion 27 is electrically connected to each of the distal-end portion 24 (image pickup device 244) and the control device 3, and functions as a relay processing unit to relay the electrical signal. Further, as long as electrical connection is possible, connection between the connecting parts detachably connected to each of the control device 3 and the light source device 4 at the connector portion 27 is not limited to the coil cable.
Next, a configuration of the control device 3 will be described. The control device 3 includes an S/P converter 301, an image processing unit 302, a brightness detection unit 303, a light control unit 304, the reading address setting unit 305, a drive signal generation unit 306, an input unit 307, a storage unit 308, a control unit 309, and a reference clock generation unit 310. According to the present embodiment, a configuration adopting the frame sequence will be described as the control device 3, but the simultaneous method is also adoptable.
The S/P converter 301 performs serial-parallel conversion on an image signal (electrical signal) received from the distal-end portion 24 via the operating unit 22 and the connector portion 27.
The image processing unit 302 generates an in-vivo image displayed by the display device 5 based on the image signal in the parallel form output from the S/P converter 301. The image processing unit 302 includes a synchronization unit 302a, a white balance (WB) adjustment unit 302b, a gain adjustment unit 302c, a gamma correction unit 302d, a D/A converter 302e, a format change unit 302f, a sample memory 302g, and a still image memory 302h.
The synchronization unit 302a inputs the image signals received as the pixel information to three memories (not shown) provided per pixel, and sequentially updates and keeps values in the respective memories, associating with the pixel addresses of the light receiving unit 244f read by the reading unit 244g, and further synchronizes the image signals in the three memories as RGB image signals. The synchronization unit 302a sequentially outputs synchronized RGB image signals to the white balance adjustment unit 302b and also outputs some of RGB image signals to the sample memory 302g for image analysis such as brightness detection.
The white balance adjustment unit 302b automatically adjusts the white balance of the RGB image signal. More specifically, the white balance adjustment unit 302b automatically adjusts the white balance of the RGB image signal based on color temperature contained in the RGB image signal. Further, in the case where the sensor unit 244a adopts multi-line reading, gain variation between the multiple lines is adjusted.
The gain adjustment unit 302c adjusts the gain of the RGB image signal. The gain adjustment unit 302c outputs the RGB signal obtained after the gain adjustment to the gamma correction unit 302d, and also outputs some of the RGB signals to the still image memory 302h for displaying a still image, a magnified image or a highlight image.
The gamma correction unit 302d executes gradation correction (gamma correction) for the RGB image signal, corresponding to the display device 5.
The D/A converter 302e converts, to an analog signal, the RGB image signal obtained after the gradation correction which is output from the gamma correction unit 302d.
The format change unit 302f changes the image signal converted to the analog signal to a file format for a moving image such as high-vision system, and outputs the image to the display device 5.
The brightness detection unit 303 detects brightness level corresponding to each of the pixels based on the RGB image signal kept in the sample memory 302g, and records the detected brightness level in a memory provided inside, and further outputs the brightness level to the control unit 309. Further, the brightness detection unit 303 calculates a white balance adjustment value, a gain control value, and a light irradiation quantity based on the detected brightness level, and outputs the white balance adjustment value to the white balance adjustment unit 302b, the gain adjustment value to the gain adjustment unit 302c while outputting the light irradiation quantity to the light control unit 304.
The light control unit 304 sets a light type, a light quantity, light emission timing, etc. of the light generated by the light source device 4 based on the light irradiation quantity calculated by the brightness detection unit 303, and transmits a light source synchronizing signal including the set conditions to the light source device 4 under the control of the control unit 309.
The reading address setting unit 305 has a function to set pixels to be read and a reading order of the pixels on the light receiving surface of the sensor unit 244a by communicating with the control unit 271 inside the endoscope 2. The control unit 271 reads type information of the sensor unit 244a contained in the first EEPROM 274 and outputs the type information to the control device 3. In other words, the reading address setting unit 305 has a function to set the pixel address of the sensor unit 244a read by the AFE unit 244b. Further, the reading address setting unit 305 outputs the set address information of the reading target pixel to the synchronization unit 302a.
The drive signal generation unit 306 generates a drive timing signal (horizontal synchronizing signal (HD) and vertical synchronizing signals (VD)) for driving the endoscope 2, and transmits the signal to the timing generator 244d (image pickup device 244) via a prescribed signal line included in the FPGA 272 and the cable assemblies 224 and 245. The timing signal includes the address information of the reading target pixel, and may be superimposed on the setting data to be transmitted to the control unit 244e (timing generator 244d).
The input unit 307 receives inputs of various kinds of signals such as the operation instruction signals that instruct operations of the endoscope system 1, for example, freeze, release, various kinds of image adjustments (highlight, electronic magnification, color tone, etc.) set by a front panel or a keyboard of the control device 3.
The storage unit 308 is implemented by a semiconductor memory such as a flash memory and a DRAM (Dynamic Random Access Memory). The storage unit 308 stores data including various kinds of programs for operating the endoscope system 1, various kinds of parameters necessary for operating the endoscope system 1, pattern information such as the test pattern signal to identify a location of abnormality (electrical signal corresponding to a specified display pattern), and the like. Also, the storage unit 308 stores the identification information and observation information of the control device 3. Here, the identification information includes individual information (ID) and a model year of the control device 3 as well as specification information and transmission rate information of the control unit 309.
The control unit 309 includes a CPU or the like, and executes drive control for the respective components including the endoscope 2 and the light source device 4, and also executes information input/output control for the respective components. The control unit 309 transmits, to the control unit 244e, the setting data for imaging control, the setting information for the test pattern signal at the time of determining abnormality, etc. via the FPGA 272 of the connector portion 27, and the signal and data required for the image pickup device 244 via a specified signal line included in the cable assemblies 224 and 245. The setting information for the test pattern includes information related to, for example, which test pattern signal is to be used in the case where there is a plurality of test patterns and at which component the test pattern signal is output for the image pickup device 244.
The reference clock generation unit 310 generates the reference clock signal which is to be the basis of operation in each of the components of the endoscope system 1, and supplies the generated reference clock signal to each of the components of the endoscope system 1. Note that either the clock generated by the reference clock generation unit 310 or the clock generated by the reference clock generation unit 273 may be used for the clock at the distal-end portion 24.
Next, a configuration of the light source device 4 will be described. The light source device 4 includes a light source 41, a light source driver 42, a rotary filter 43, a drive unit 44, a driving driver 45, and a light source controller 46.
The light source 41 includes a white LED (Light Emitting Diode), a xenon lamp or the like, and generates the white light under the control of the light source controller 46. The light source driver 42 causes the light source 41 to generate the white light by supplying current to the light source 41 under the control of the light source controller 46. The white light generated from the light source 41 is emitted from a distal end of the distal-end portion 24 via the rotary filter 43, a condenser lens (not shown), and the light guide 241.
The rotary filter 43 is disposed on an optical path of the white light generated by the light source 41, and rotated so as to pass only the light having a specified wavelength band of the white light generated by the light source 41. More specifically, the rotary filter 43 includes a red filter 431, a green filter 432, and a blue filter 433, which respectively pass the lights having the wavelength bands of red light (R), green light (G) and blue light (B). The rotary filter 43 is rotated, thereby sequentially passing the light having the wavelength bands of red, green and blue (for example, red: 600 nm to 700 nm, green: 500 nm to 600 nm, blue: 400 nm to 500 nm). This allows the white light generated from the light source 41 to sequentially emit any one of the red light, green light, and blue light having the narrowed wavelength band to the endoscope 2.
The drive unit 44 includes a stepping motor, a DC motor or the like, and rotates the rotary filter 43. The driving driver 45 supplies a specified current to the drive unit 44 under the control of the light source controller 46.
The light source controller 46 controls a current amount to be supplied to the light source 41 in accordance with a light source synchronizing signal transmitted from the light control unit 304. Also, the light source controller 46 rotates the rotary filter 43 by driving the drive unit 44 via the driving driver 45 under the control of the control unit 309.
The display device 5 has a function to receive, from the control device 3, the in-vivo image (an image for a moving image or an image for a still image) generated by the control device 3 via the video cable to display the in-vivo image. The display device 5 is formed of a liquid crystal, an organic EL (Electro Luminescence), or the like.
In the endoscope system 1 having the above-described configuration, abnormality location is identified in the case where abnormality occurs in a display image based an electrical signal in the electrical signal (image information) output from the endoscope 2. An exemplary way to identify the abnormality location may be a method in which the control unit 244e refers to the storage unit 244k and outputs a target test pattern signal based on the setting information of the test pattern signal from the control unit 309 and the test pattern signal is output via the timing generator 244d from any of the respective components (sensor unit 244a, P/S converter 244c, noise reduction unit 244h, AGC unit 244i, and A/D converter 244j). In this instance, the test pattern signal output from each of the components is transmitted to the operating unit 22 side via the signal line same as the signal line used to transmit the image of the endoscope 2. At this point, in the case where there is a plurality of the target components outputting the test pattern signal, each of the components individually outputs the test pattern signal.
Now, input/output mode of the pixel signal (image signal) of the sensor unit 244a will be described.
The operation of the sensor unit 244a in the pixel P having the above-described configuration will be described with reference to
In the light receiving unit 244f, a row (M) is selected by a row selection pulse φSE from the vertical scanning circuit VC (row selection circuit), and the pixel signals of the pixels in the selected row are sequentially output as the pixel output voltage Vpout in accordance with the column number (N). For example, when the row M=1 is selected, the pixel output voltage Vpout is output from each of the pixels in numerical order of the column numbers (N). After that, the pixel signal for the selected row (M) is output from each of the pixels. Thus, the image signal from each of the pixels P is output as the image signal from the sensor unit 244a to the outside after reducing the noise by using the correlated double sampling, for example. At this point, whether the pixel signal output from the pixel P includes the pixel information (signal electric charge of photodiode PD) is controlled by ON/OFF control of a column selection transistor R-TR.
First, operation in the case where the pixel reads the signal level will be described with reference to
Here, the pixel output voltage Vpout is connected to a CDS circuit (correlated double sampling circuit) C1 (see
After completion of the reset level sampling by the sample-and-hold pulse φSHP, the reset pulse φRSS is switched to the low level. After the reset pulse φRSS is stabilized at the low level (time t2), the electric charge transfer pulse φTR is switched to the high level, and the voltage of the signal electric charge accumulated in the photodiode PD is converted at the capacitor FD, and also the pixel signal is output as the pixel output voltage Vpout at the output transistor SF-TR.
After the pixel signal is output to the pixel output voltage Vpout (time t3), a pixel signal level is sampled by a sample-and-hold pulse φSHD, and the image signal obtained by eliminating reset noise by a CDS circuit C1 is output as an output voltage Vcout to the outside of the sensor unit 244a by input of an output pulse φTS. The CDS circuit C1 is connected to a horizontal read line via the column control reset transistor R-TR. Further, the output voltage Vcout output during a period A1 constitutes one frame.
Next, operation in the case where the pixel reads the reset level will be described with reference to
Here, the pixel output voltage Vpout is sampled by rise of a sample-and-hold pulse φSHP at time t1. After completion of reset level sampling by the sample-and-hold pulse φSHP, the reset pulse φRSS is controlled to be kept at the high level. In this state, the electric charge transfer pulse φTR is switched to the high level, and the signal electric charge accumulated in the photodiode PD is taken out. In this case, the capacitor FD is fixed at the reset level by the reset pulse φRSS, and therefore, the reset level is output to the pixel output voltage Vpout. After that, sampling of the pixel output voltage Vpout is executed by the sample-and-hold pulse φSHD (time t3).
The pixel signal and the reset level read from the CDS circuit C1 in each column are obtained as the pixel output voltage Vpout per row by sequentially switching ON/OFF the column control reset transistor R-TR for each of the columns. After completion of reading up to the column m, the row selection pulse φSE is switched to the low level to finish reading the row. Thus, the row selection pulse φSE is sequentially switched ON/OFF from the row selection pulses φSE1 to φSEm, thereby achieving to read one frame.
When outputting the test pattern illustrated in
By adopting the above-described configuration, the case of performing normal operation or the case of performing test pattern reading can be executed only by controlling operation of the reset pulse φRSS.
On the other hand, column-by-column control is not possible in the output mode when the captured image according to the related art is output as illustrated in
As described above, the column control reset transistor R-TR is capable of performing the column-by-column control, and the output mode of the signal from each of the pixels P arranged in the rows (M) and the columns (N) (electric charge amount transferred by the pixel) can be controlled by the pixel unit by executing the column-by-column control of the column control reset transistor R-TR for each of the pixels P. With this configuration, the columns in the selected horizontal line can be selected according to the present embodiment while only the horizontal line is selected for the reading target according to the related art. As a result, the degree of freedom in the output mode of the pixel P can be improved. Moreover, according to the present embodiment, normal reading control (outputting signals including pixel information from all of pixels), test pattern switching control, and pattern control (display mode) for the test pattern can be executed only by controlling the operation of the reset pulse φRSS.
Inclusion and non-inclusion of the pixel information may be alternately set in the column direction as illustrated in
Thus, by controlling the output mode of the signal of the respective pixels P arranged in the rows (M) and columns (N), it is possible to identify abnormality at the sensor unit 244a by the test pattern signal at the time of determining abnormality of the sensor unit 244a, and also abnormality determination can be executed by the pixel unit. Further, the test pattern may be used for adjusting the sensor unit 244a as well.
In the case of outputting the above-described test pattern signal, phase adjustment for the pulse at the A/D converter 244j can be executed, for example, by using the test patterns having different brightness level between adjacent pixels.
Adjusting the sampling pulse phase at the A/D converter 244j is to adjust the sampling pulse to the optimal position (phase) inside the video signal of one pixel by outputting a test pattern in which the brightness level is highlighted in every other pixel. For instance, the optimal position of the sampling pulse is a position at a peak point of the analog video signal waveform, obtained by cutting frequency components higher than a maximum video signal frequency by using a lowpass filter in the arrangement of adjacent pixels P10, P11, P20 and P21 having different brightness levels, as illustrated in
More specifically, the phase of the sampling pulse is adjusted to the highest signal level point (peak point) in the analog video signal of one pixel (
The step having the highest video signal level is determined as the optimal sampling pulse position (phase) based on the detection results of the video signal level, and the determined optimal position is stored in the second EEPROM 275 or the storage unit 308 as an adjustment value, so that the phase position of the sampling pulse is read and set at the time starting the system. Note that this sampling pulse adjustment is performed asynchronously with the video signal.
Here, in the case where the sampling pulse is swept in the phase step sufficiently shorter compared to the one-pixel video signal transfer period R0 within the one-pixel video signal transfer period R0 to acquire the level of the video signal, it takes some time to scan all the steps within the one-pixel video signal transfer period R0 by the number of steps in order to detect the optimal phase from the acquired video levels. In other words, it takes a long time in the case where the number of steps is increased by making each scanning step short for sake of improving sampling accuracy or in the case where the system has a long one-pixel video signal transfer period R0.
In view of the situation, the above-described adjustment method may be suitably modified as described below. An adjustment method is to create groups for respective video signal input timings to the A/D converter 244j, and limit a scanning range of the sampling pulse to a video signal transfer period R10 shorter compared to the video signal transfer period R0 for each of the groups, thereby reducing the adjustment time (
By adopting the above-described method, the scanning range in the case of adjusting the phase of the sampling pulse per group can be minimized within the one-pixel video signal transfer period R10. As a result, the adjustment time can be considerably shortened.
Also, in the endoscope 2, a cable transmission distance for a signal varies because the length of the inserting portion 21 varies depending on a used region of a human body. For instance, in the endoscope including the A/D converter mounted on the connector portion 27, the video signal input timing to the A/D converter varies due to the above-described reason, but in the case of executing the same adjusting method for the inserting portion having the longest length and the inserting portion having the shortest length, the video signal transfer period R0 is deviated and an obtained position of the sampling pulse may differs from the optimal position (
In order to avoid obtaining such a position of the sampling pulse different from the optimal position, in the type of the endoscope 2 where no optimal position exists within the scanning range in accordance with the cable transmission distance, adjustment is executed by setting the scanning range of the sampling pulse to a video signal transfer period R11 illustrated in
Note that the above-described method is not limited to the sampling pulse phase adjustment at the A/D converter 244j. For instance, the method may be applied to detect an optimal phase of a sampling pulse at the noise reduction unit 244h and the AGC unit 244i inside the AFE unit 244b.
Here, according to the above-described video signal transmission, phase shift may occur at the image position and in the signal at the image pickup device 244 due to image position displacement or signal delay at the image processing unit 302 on the receiving side. A method of correcting such a phase shift is to superimpose correction fixed data Dc, which is to be positional information for images and phase adjustment information, inside the serialize video data. Correction is executed by detecting the correction fixed data and detecting displacement of the image position and phase shift.
However, in the case where the video data has the same data pattern as the correction fixed data at the time of detecting the correction fixed data (e.g., video signal data D0), a correction circuit inside the image processing unit 302 may erroneously recognize the video signal data D0 as the correction fixed data Dc and erroneous correction may be made (
There is a method to avoid such an erroneous correction caused by erroneous recognition, in which only the vicinity of the timing when the correction fixed data Dc (correction fixed data monitoring period R20) is transferred is monitored by the correction circuit (e.g., image processing unit 302 or control unit 309) on the receiving side (see
The above-described method of avoiding correction by the erroneous recognition is not limited between the A/D converter 244j outputting the serial video data and the image processing unit 302. For example, the method may be used for delay correction of the transmission distance and enhancement of resistance against disturbance noise, etc. in control signal communication between two circuits.
According to the above-described present embodiment, the control unit 244e performs the pixel-by-pixel control for the output mode of the electrical signal output from the respective pixels P so as to output the electrical signal (test pattern signal) corresponding to the prescribed display pattern, thereby achieving to identify a location of abnormality inside the endoscope 2, particularly details of the abnormality location at the sensor unit 244a. Further, the control unit 244e is configured to output the test pattern signal to any of the following components (sensor unit 244a, P/S converter 244c, noise reduction unit 244h, AGC unit 244i, and A/D converter 244j) via the timing generator 244d. As a result, optical and electrical evaluation is performed based on the obtained signal and it is possible to identify the location of abnormality at the image pickup device 244 in detail.
In this case, the optical and electrical evaluation based on the obtained signal may be conducted by an observer by using images and the like displayed on the display device, or may be automatically performed on the control device 3 side by comparing the test pattern signal obtained from the endoscope 2 side with the test pattern signal stored in the storage unit 308.
Also, according to the present embodiment, the test pattern signals are output from the respective components in parallel and can be simultaneously output splitting on the screen. Accordingly, it is possible to identify abnormal locations in the plurality of components at the same time.
Also, according to the above-described embodiment, electrical signal output may be controlled by performing ON/OFF control of the buffer output at the P/S converter 244c or the operating unit 22. With this configuration, the electrical signals respectively output from the operating unit 22 and the distal-end portion 24 can be separated. Particularly, this configuration can be used to examine EMC (Electro-Magnetic Compatibility; electromagnetic compatibility) of the operating unit 22 and the distal-end portion 24.
According to the above-described present embodiment, it has been described that the light source device 4 adopts the frame sequential method, including the rotary filter 43, but the light source device may also adopt the simultaneous method without the rotary filter 43 as long as a color filter is included on the image pickup device 244 side.
According to the modified example 1, three test pixels PP1, PP2 and PP3 capable of receiving the light (not shielded) are provided on the optical black area PEB1. The three test pixels PP1, PP2 and PP3 are arranged at specified intervals, for example, at the interval corresponding to one pixel. The sensor unit 244a reads the optical black area PEB1 by the normal reading method.
By arranging the three test pixels PP1, PP2 and PP3 at the specified intervals, crosstalk level can be checked. Also, since the interval between the pixels is clear, optical resolution can be checked without using the optical system. A center position of the effective pixel area PEP can be detected by placing one of the three test pixels at the center position of the effective pixel area (center portion of one side of the rectangular-shaped effective pixel area). With this configuration, it is possible to identify the abnormality location far more in detail.
According to the modified example 2, the optical black area PEB2 includes two test pixel areas PW1 and PW2 capable of receiving the light (not shielded). The two test pixel areas PW1 and PW2 have an approximate rectangular-shape and extend in directions orthogonal to each other.
Optical distortion (distortion) can be checked by using image information obtained from the test pixel areas PW1 and PW2 that have an approximate rectangular-shape and extend. Also, since the two test pixel areas PW1 and PW2 are orthogonally arranged, distortion of the two orthogonal directions can be detected in the effective pixel area PEP. With this configuration, it is possible to identify the abnormality location far more in detail.
The test pixels PP1, PP2, PP3 and the test pixel areas PW1, PW2 according to the above-described modified examples 1 and 2 can be optionally combined. Also, the arranged position of each of the test pixels can be suitably adjusted.
According to the above-described modified example 3, abnormality at the operating unit may be identified, in addition to the above-described embodiments. With this configuration, it is possible to identify the abnormality location far more in detail. Abnormality at a component other than the operating unit can be also identified by outputting the test pattern signal from the component in the case the component has the configuration capable of outputting the test pattern signal (for example, connector portion 27).
As described above, the imaging apparatus and the imaging system according to the present invention are useful to identify the abnormality location inside the imaging apparatus in detail.
Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
Number | Date | Country | Kind |
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2012-144564 | Jun 2012 | JP | national |
This application is a continuation of PCT international application Ser. No. PCT/JP2013/065818 filed on Jun. 7, 2013 which designates the United States, incorporated herein by reference, and which claims the benefit of priority from Japanese Patent Application No. 2012-144564, filed on Jun. 27, 2012, incorporated herein by reference.
Number | Date | Country | |
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Parent | PCT/JP2013/065818 | Jun 2013 | US |
Child | 14200712 | US |