JP2005244391A - Image processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an image processor in which the performance is always sustained in optimal state at the time of shipping by grasping and correcting the amplification factor of an amplifier at the present time. <P>SOLUTION: Amplification factor is detected conveniently and correctly by replacing an image pick-up signal being inputted to an amplifier with a signal having a known level at a predetermined timing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image processing apparatus that includes an image sensor such as a CCD sensor and captures, records, and reproduces still images and moving images.

  2. Description of the Related Art Conventionally, an image processing apparatus such as an electronic camera that records and reproduces a still image or a moving image captured by a solid-state imaging device such as a CCD using a memory card having a solid-state memory element as a recording medium is already on the market.

  In such an apparatus, an optical image of a subject is converted into an electrical signal by a solid-state imaging device such as a CCD, and the level required by a signal processing unit that records and reproduces a captured still image or moving image by an amplifier at a later stage. It is common to be amplified. Here, the output voltage of a solid-state imaging device such as a CCD becomes a value proportional to the exposure amount below the saturation output voltage. For example, when the incident light quantity is insufficient, the output voltage is increased by increasing the accumulation time. be able to. However, if the accumulation time is lengthened, a noise component called dark output voltage increases in proportion to the accumulation time when the temperature is constant, and the signal-to-noise ratio (hereinafter, S / N ratio) of the output signal deteriorates. .

  Therefore, the output voltage of a solid-state imaging device such as a CCD can be lowered and amplified to a required level by a later-stage amplifier. In that case, in order to ensure the required S / N ratio, an amplifier having a better noise figure is required as the input signal level is lower.

  From these, the amount of light to be captured, the accumulation time, the amplification factor of the amplifier, and the respective ratios, that is, the level distribution, to obtain the signal level required by the signal processing unit, determines the performance of the image processing apparatus. Is a very important item.

  Therefore, such an apparatus is shipped after being adjusted in advance so that the amount of captured light, the accumulation time, and the amplification degree of the amplifier are optimally distributed so that the performance can be maximized.

  In some electronic cameras, by selecting the shooting conditions such as the shutter speed, the amplification factor of the amplifier is switched automatically or manually, and the sensitivity condition equivalent to the ISO sensitivity of the film in a silver halide camera There is something that can be switched.

Such an electronic camera is also shipped after being adjusted in advance so that the amount of captured light, the accumulation time, and the amplification level of the amplifier are optimally distributed so that the performance can be maximized for each sensitivity condition. .
JP 2002-94797 A

  However, in such an image processing apparatus such as a conventional electronic camera, the signal level obtained by converting an optical image of a subject into an electrical signal by a solid-state image sensor such as a CCD is not known during operation. Even if the amplification factor of the amplifier changes due to a change or the like, and the sensitivity condition is switched, it is difficult to detect whether the amplification factor of the amplifier is actually the desired amplification factor even if the amplification factor of the amplifier is switched. . Therefore, there is a problem that it is not known whether the amount of light taken in, the accumulation time, and the amplification degree of the amplifier maintain the optimum level distribution adjusted at the time of shipment.

  Further, when the input level to the signal processing unit is abnormal, there is a problem that it cannot be immediately determined whether the cause is in a solid-state imaging device such as a CCD or in an amplifier in the subsequent stage.

  In order to solve this problem, it is conceivable to detect the amplification degree of the amplifier by using the property that the output voltage in the dark increases in proportion to the accumulation time when the temperature is constant. Since the output voltage is greatly affected by temperature, it is necessary to accurately detect the temperature. Further, since the dark output voltage has a large individual difference, it is necessary to grasp the characteristics of each element.

  In view of the above-described conventional problems, the present invention can easily and accurately detect the amplification level of the amplifier at the present time, and can easily identify the cause of the problem at the time of abnormality. It is possible to determine whether the amplification level of the amplifier maintains the optimal level distribution adjusted at the time of shipment. For amplifiers that can switch the amplification level, the amplification level at the time of shipment adjustment can be corrected, and the performance is always maximized. It is an object of the present invention to provide an image processing apparatus that can perform such processing.

  According to one aspect of the present invention, an imaging unit that converts an optical image of a subject into an electrical signal, a signal generation unit that generates an electrical signal of a predetermined level, an electrical signal after photoelectric conversion by the imaging unit, and the signal generation A signal selecting means for selecting and outputting the output signal of the means, an amplifying means for amplifying the output electric signal from the signal selecting means with a predetermined amplification degree, and a signal level detection for detecting the output signal level of the amplifying means And an image processing apparatus comprising: system control means for detecting an amplification degree of the amplification means from information of the signal level detection means.

  According to the above means, it is possible to accurately detect the amplification degree of the amplifier that has changed due to the use environment temperature, change with time, etc., and when the input level to the signal processing unit is abnormal, the cause is a solid state such as a CCD. It is possible to immediately identify whether the image sensor is in the image sensor or the amplifier in the subsequent stage.

  According to another aspect of the present invention, an imaging unit that converts an optical image of a subject into an electrical signal, a signal generation unit that generates an electrical signal of a predetermined level, an electrical signal after photoelectric conversion by the imaging unit, and the signal A signal selecting means for selecting and outputting the output signal of the generating means; an amplifying means for amplifying the output electric signal from the signal selecting means with a predetermined amplification; and a signal level for detecting the output signal level of the amplifying means There is provided an image processing apparatus comprising: a detection unit; a system control unit that detects the amplification degree of the amplification unit from information of the signal level detection unit; and a unit that stores the amplification degree information of the amplification unit. The

  According to the above means, it is possible to accurately detect the amplification degree of the amplifier which has changed due to the use environment temperature, the change with time, etc., and the amount of light taken in from the light source to secure the required gradation and S / N ratio. The level distribution between the accumulation time and the amplification degree of the electric signal after photoelectric conversion can be reviewed.

  In addition, when an amplifier capable of varying the amplification degree is provided, by correcting to a desired amplification degree, it is possible to maintain the level distribution and always maintain the gradation and the S / N ratio at the optimal state at the time of shipment. Become.

  As described above, according to the present invention, it is possible to accurately detect the amplification degree of the amplifier that has changed due to the use environment temperature, the change with time, or the like.

  Thereby, when the input level to the signal processing unit is abnormal, it is possible to immediately identify whether the cause is in the solid-state imaging device such as a CCD or the amplifier in the subsequent stage.

  In addition, it is possible to review the level distribution of the amount of light captured from the light source, the accumulation time, and the amplification degree of the electric signal after photoelectric conversion in order to ensure the required gradation and S / N ratio.

  In addition, when an amplifier capable of varying the amplification degree is provided, by correcting to a desired amplification degree, it is possible to maintain the level distribution and always maintain the gradation and the S / N ratio at the optimal state at the time of shipment. Become.

  FIG. 1 is a diagram showing the characteristics of the first embodiment of the image processing apparatus according to the present invention. In FIG. 1, 11 is a photoelectric conversion unit that converts an optical image of a subject into an electrical signal, and 12 is a predetermined level of electricity. A signal generating unit for generating a signal, 13 is a signal selecting unit for selecting and outputting the output electric signal of the photoelectric conversion unit and the output signal of the signal generating unit, and 14 is a predetermined amplification degree of the input electric signal. An amplifying unit for amplifying, 15 is a signal level detecting unit for detecting an output signal level of the amplifying unit, 16 is a system control unit for detecting the amplification degree of the amplifying unit from information of the signal level detecting unit, and 17 is a photographed still image. It is a signal processing unit that records and reproduces images and moving images.

  In the above configuration, the analog image signal generated by the photoelectric conversion unit 11 is input to the amplification unit 14 by the signal selection unit 13, amplified at a predetermined amplification degree, and then subjected to predetermined processing by the signal processing unit 17. Images and moving images are recorded and played back.

  Here, in the image processing apparatus according to the first embodiment of the present invention, for example, a field programmable gate array (FPGA) and a digital / analog converter (DAC) are provided at a predetermined timing by the signal selection unit 13 that is an analog switch, for example. The output signal of the signal generator 12 connected in series is selected and input to the amplifier 14. The output signal level of the amplification unit 14 is detected by, for example, a signal level detection unit 15 that is a detection circuit, and the detection information is sent to the system control unit 16.

  Thereby, since the output signal level of the signal generation unit 12, that is, the input signal level of the amplification unit 14, is known in advance, the system control unit 16 can calculate an accurate amplification degree of the amplifier 14.

  FIG. 2 is a diagram showing the characteristics of the second embodiment of the image processing apparatus according to the present invention. In FIG. 2, 21 is a photoelectric conversion unit that converts an optical image of a subject into an electrical signal, and 22 is a predetermined level of electricity. A signal generation unit for generating a signal, 23 is a signal selection unit for selecting and outputting the output electric signal of the photoelectric conversion unit and the output signal of the signal generation unit, and 24 is an input electric signal according to a command from the outside An amplification unit that can be switched to a desired amplification degree, 25 is a signal level detection unit that detects the output signal level of the amplification unit, and 26 sends an amplification degree command to the amplification unit 24, and the signal level detection unit A system control unit that detects the amplification level of the amplification unit from the information, 27 is a memory unit that stores the amplification level information of the amplification unit detected at the end of shipping adjustment or at a predetermined timing, and 28 is a captured still image or moving image. Recording an image, a signal processing unit for reproducing.

  In the above configuration, the analog image signal generated by the photoelectric conversion unit 21 is input to the amplification unit 24 by the signal selection unit 23, amplified with the amplification degree based on the command from the system control unit 26, and then predetermined by the signal processing unit 28. This process is performed, and still images and moving images are recorded and reproduced.

  Here, in the image processing apparatus according to the second embodiment of the present invention, at a predetermined timing, for example, the signal selection unit 23 that is an analog switch selects the output signal of the signal generation unit 22 in which an FPGA and a DAC are connected in series, for example. And input to the amplifying unit 24. The output signal level of the amplifying unit 24 is detected by, for example, a signal level detecting unit 25 that is a detection circuit, and the detection information is sent to the system control unit 26.

  Thus, since the output signal level of the signal generation unit 22, that is, the input signal level of the amplification unit 24 is known in advance, the system control unit 26 calculates an accurate amplification degree of the amplifier 24 with respect to its own amplification degree command. be able to. Further, the amplification degree information stored in the memory unit 27 can be compared. Further, it can be stored in the memory unit 27 as the latest amplification degree information.

  3 to 5 are diagrams showing examples of signal waveforms output from the signal generation units 12 and 22 described in the first and second embodiments in the image processing apparatus of the present invention. FIG. 3 shows a DC wave as an example of a signal waveform output from the signal generator of the present invention, FIG. 4 shows a ramp wave, and FIG. 5 shows a staircase wave. In the present invention, it is preferable to use the signal that can accurately detect the amplification degree of the amplification means. However, in the present invention, the signal waveform output by the signal generating means is not limited to the above signal, and other rectangular waves, sine waves, and the like can be used, and a combination waveform thereof can also be used. .

  FIG. 6 is a drawing showing the characteristics of the third embodiment of the image processing apparatus of the present invention, and is an example when the present invention is applied to an electronic camera. In the figure, 31 is an optical system for condensing light from a light source, 32 is a diaphragm mechanism for controlling the amount of incident light, 33 is a shutter mechanism for controlling an exposure time, and 34 is a photoelectric conversion that converts an optical image of a subject into an electrical signal. 35, a signal generator 35 for generating an electrical signal of a predetermined level, 36 a signal selector for selecting and outputting the output electrical signal of the photoelectric converter and the output signal of the signal generator, and 37 for the photoelectric conversion A CDS (correlated double sampling) unit that generates a pixel signal from the output signal of the unit, 38 an amplifying unit that can switch the input electrical signal to a desired amplification degree according to an external command, and 39 the amplifying unit An analog / digital conversion (ADC) unit 40 for converting the output analog signal into a digital signal, and recording and reproduction of still images and moving images taken from the output digital signal of the ADC unit The signal processing unit 41 is a signal level detection unit for detecting the output analog signal level of the amplification unit from the output digital signal of the ADC unit, 42 is an operation unit that can designate a change of the operation mode during operation, and 43 is mainly used. A system control unit for selecting and outputting the output signal of the signal generation means to the signal selection unit at a predetermined timing, and detecting the amplification degree of the amplification unit from the information of the signal level detection unit, 44 is finished shipping adjustment It is a memory part which memorize | stores the amplification degree information of the said amplification part detected at the time or predetermined timing.

  In the above configuration, the output electrical signal of the photoelectric conversion unit 34 is input to the CDS unit 37 by the signal selection unit 36 to become a pixel signal, input to the amplification unit 38, and amplified after amplification based on a command from the system control unit 43. Then, the signal is converted into a digital signal by the ADC unit 39, and predetermined processing is performed by the signal processing unit 40 to record and reproduce a still image or a moving image.

  Here, in the image processing apparatus according to the third embodiment of the present invention, at a predetermined timing, for example, an output signal of the signal generation unit 35 in which an FPGA and a DAC are connected in series is selected by the signal selection unit 36 that is an analog switch, for example. Then, it is input to the CDS unit 37 to become a pixel signal and input to the amplifying unit 38. The output signal of the amplifying unit 38 is converted into a digital signal by the ADC unit 39, and then, for example, the output analog signal level of the amplifying unit is detected by a signal level detecting unit 41 in which a DAC and a detection circuit are connected in series. It is sent to the system control unit 43.

  As a result, the system control unit 43 knows in advance the signal level when the output signal of the signal generation unit 35 is converted to a pixel signal by the CDS unit 37, that is, the input signal level of the amplification unit 38, so It is possible to calculate the exact amplification degree of the amplifier 38 with respect to the command. Further, it can be compared with the amplification degree information stored in the memory unit 44. Further, it can be stored in the memory unit 44 as the latest amplification degree information.

  FIG. 7 is a diagram illustrating an example of a signal waveform output from the signal generation unit 35 described in the third embodiment in the image processing apparatus of the present invention. The signal waveform output by the signal generating means of the present invention is preferably a waveform that alternately repeats the reset level of the photoelectric conversion unit and the pixel signal level, as shown in FIG. However, in the present invention, the signal waveform output from the signal generating means is not limited to the signal, and the ramp wave, sine wave, or the like can be used, or a combination waveform thereof can also be used.

  In the image processing apparatus of the present invention described above, the system control unit sends a command to the signal selection unit, selects the output signal of the signal generation unit, inputs a predetermined level signal to the amplification unit, and outputs the output signal level. From the information, the amplification degree of the amplification unit is detected. This detection does not take in a valid image signal, for example, at the timing of at least one of power-on, before imaging start, vertical blanking period, horizontal blanking period, and optical black pixel period of the photoelectric conversion unit. It is preferred to do so.

  Further, in the image processing apparatus of the present invention provided with an operation unit that can specify the change of the operation mode during operation, for example, the operation unit is instructed at the end of shipping adjustment, and the user instructs the operation unit at a desired timing. As described above, it is preferable to perform the detection from the information of the operation unit.

  Further, in the image processing apparatus of the present invention provided with a counting unit for the cumulative imaging time or cumulative number of captured images from the end of shipment adjustment of the amplification unit, for example, the detection is performed when the cumulative imaging time or the cumulative number of captured images reaches a predetermined value. Is preferred.

  In the image processing apparatus of the present invention provided with the ambient temperature detection unit of the amplification unit, it is preferable to perform the detection when the ambient temperature of the amplification unit satisfies a predetermined condition, for example.

  Further, in the image processing apparatus of the present invention having a signal processing unit capable of setting whether to perform recording and reproduction, for example, a period during which the detection is performed by selecting an output signal of a signal generating unit, a photoelectric conversion unit Therefore, it is preferable not to execute recording and reproduction in the signal processing unit.

  In the image processing apparatus of the present invention capable of controlling supply of at least one of the power supply to the photoelectric conversion unit and the timing signal, for example, during the period in which the detection is performed by selecting the output signal of the signal generation unit. Since signal conversion in the conversion unit is unnecessary, it is preferable to stop supply of at least one of the power source and the timing signal to the photoelectric conversion unit from the viewpoint of power saving and suppression of unnecessary signal radiation.

It is a block diagram which shows the main structures in 1st Embodiment in the image processing apparatus of this invention. It is a block diagram which shows the main structures in 2nd Embodiment in the image processing apparatus of this invention. It is drawing which shows the direct current | flow wave which is an example of the signal waveform which the signal generation part in the image processing apparatus of this invention outputs. It is drawing which shows the ramp wave which is an example of the signal waveform which the signal generation part in the image processing apparatus of this invention outputs. It is drawing which shows the staircase wave which is an example of the signal waveform which the signal generation part in the image processing apparatus of this invention outputs. It is a block diagram which shows the main structures in 3rd Embodiment in the image processing apparatus of this invention. It is drawing which shows the waveform which repeats alternately the reset level which is an example of the signal waveform which the signal generation part in the image processing apparatus of this invention outputs, and a pixel signal level.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Photoelectric conversion part 12 Signal generation part 13 Signal selection part 14 Amplification part 15 Signal level detection part 16 System control part 17 Signal processing part 21 Photoelectric conversion part 22 Signal generation part 23 Signal selection part 24 Amplification part 25 Signal level detection part 26 System Control unit 27 Memory unit 28 Signal processing unit 31 Optical system 32 Aperture mechanism 33 Shutter mechanism 34 Photoelectric conversion unit 35 Signal generation unit 36 Signal selection unit 37 CDS unit 38 Amplification unit 39 ADC unit 40 Signal processing unit 41 Signal level detection unit 42 Operation Part 43 system control part 44 memory part

Claims (18)

An image processing apparatus comprising: an imaging unit that converts at least an optical image of a subject into an electrical signal; and an amplification unit that amplifies an electrical signal after photoelectric conversion by the imaging unit with a predetermined amplification degree.
Signal generating means for generating an electrical signal of a predetermined level, signal selecting means for selecting and outputting the electrical signal after photoelectric conversion by the imaging means and the output signal of the signal generating means, and the output signal level of the amplifying means An image processing apparatus comprising: a signal level detection means for detecting a signal level; and a system control means for detecting an amplification degree of the amplification means from information of the signal level detection means.   The image processing apparatus according to claim 1, further comprising means for storing amplification degree information of the amplification means.   The image processing apparatus according to claim 2, wherein the amplification degree information of the amplification unit is amplification degree information at the end of shipment adjustment of the amplification unit.   The image processing apparatus according to claim 2, wherein the amplification degree information of the amplification means is detected amplification degree information of the amplification means.   The image processing apparatus according to claim 2, wherein the stored amplification degree information of the amplification unit is updated to the latest detection information.   6. The image processing apparatus according to claim 1, wherein the amplification unit can switch the amplification degree according to a command from the system control unit.   7. The image processing apparatus having an operation unit capable of designating change of an operation mode during operation, wherein the system control unit switches the amplification degree of the amplification unit based on information of the operation unit. Image processing apparatus.   8. The signal generation unit according to claim 1, wherein the signal generation unit generates a signal having a waveform of a direct current wave, a rectangular wave, a stepped wave, a ramp wave, or a combination of two or more thereof. The image processing apparatus described.   In an image processing apparatus provided with CDS (correlated double sampling) means for generating a pixel signal from an output signal of the imaging means, the signal generating means has a waveform that alternately repeats the reset level and the pixel signal level of the imaging means. The image processing apparatus according to claim 1, wherein the signal is generated.   The image processing apparatus according to claim 1, wherein the signal generation unit selects and outputs a predetermined signal according to a command from the system control unit.   The image processing apparatus according to claim 1, wherein the signal generation unit switches whether to output a predetermined signal according to a command from the system control unit.   12. The image processing according to claim 1, wherein the signal selection unit selects and outputs an output signal of the signal generation unit according to a command from the system control unit. apparatus.   The system control means outputs the output signal of the signal generation means at at least one timing among power-on, before imaging start, vertical blanking period, horizontal blanking period, and optical black pixel period of the imaging means. The image processing apparatus according to claim 12, wherein a command to select and output the is output.   In the image processing apparatus having an operation unit capable of designating the change of the operation mode during operation, the system control unit issues an instruction to select and output the output signal of the signal generation unit from the information of the operation unit The image processing apparatus according to claim 12.   In the image processing apparatus provided with a counting unit for the cumulative imaging time or the cumulative number of captured images from the end of the shipping adjustment of the amplification unit, the system control unit selects the output signal of the signal generation unit from the information of the counting unit The image processing apparatus according to claim 12, wherein a command to be output is performed.   In the image processing apparatus provided with the ambient temperature detection means of the amplification means, the system control means issues a command to select and output the output signal of the signal generation means from the information of the ambient temperature detection means. The image processing apparatus according to claim 12.   In the image processing apparatus provided with a signal processing means capable of setting whether to perform recording and reproduction from the output signal of the amplification means by the system control means, the system control means outputs the output signal of the signal generation means 17. The image processing apparatus according to claim 1, wherein a command not to execute recording and reproduction is issued to the signal processing unit during a period of selecting and outputting.   In the image processing apparatus capable of controlling at least one of the power supply to the imaging unit and the timing signal by the system control unit, the system control unit selects and outputs the output signal of the signal generation unit 18. The image processing apparatus according to claim 1, wherein at least one of a power supply to the imaging unit and a timing signal is stopped during a period during which the image capturing unit is operated.

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