JP3300175B2 - Imaging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus, and more particularly to an image pickup apparatus using a solid-state image pickup device comprising a plurality of pixels.

[0002]

2. Description of the Related Art In recent years, a system for processing a video signal from a camera using a charge coupled device (hereinafter abbreviated as "CCD") as an image sensor by a personal computer or a workstation system has been developed. I have. These have been applied to homes under the multimedia concept led by the Ministry of International Trade and Industry, and the range of application to home information boards and portable information terminals in home automation systems is expanding.

Given such applications, it is considered that in order to reduce the size of these devices, it is often used to separate the CCD image pickup unit and the signal processing unit and mount only the CCD image pickup unit on the device. Can be In addition, in this case, it is expected that the wiring between the CCD image pickup unit and the signal processing unit will be variously changed depending on the usage at home. However, the signal output from the CCD image pickup unit has a high frequency of about 13.5 MHz, and the fact that the signal level is degraded by this wiring has been pointed out for a long time. There is an urgent need to develop a technique for correcting by some means. Conventionally, the following techniques have been known as techniques for correcting such signal level deterioration due to the wiring length.

FIG. 14 is a schematic block diagram showing such a conventional imaging apparatus. In the figure, 1 is a video camera, 3 is a transmission cable, 5 is a cable length determination circuit, 6 is a gain control amplifier, 7 is an input amplifier, 8 is a signal processing circuit,
9 is a connector. Further, the cable length determination circuit 5, the gain control amplifier 6, the input amplifier 7, and the signal processing circuit 8 constitute the receiver 2. The operation of the conventional imaging device configured as described above will be described below.

A video signal picked up by the video camera 1 is
The signal reaches the input amplifier 7 via the transmission cable 3. The output of the input amplifier 7 is adjusted to a constant amplitude by multiplication with the output voltage of the cable length determination circuit 5 in the gain control amplifier 6 and sent to the signal processing circuit 8. The input amplifier 7
Is a circuit for performing impedance matching of a high-frequency video signal and performing impedance conversion,
Not related to essential operation.

The connector 9 has a plurality of connection terminals built therein, and the length of the transmission cable 3 is defined in advance in a plurality of cases except for a terminal for passing a video signal.
A terminal corresponding to the prescribed length is provided, and the terminal is grounded. The cable length determining circuit 5 selects a voltage to be output to the gain control amplifier 6 according to the position of the grounded terminal. This is intended to guarantee the deterioration of the video signal supplied from the video camera 1 due to the transmission cable 3 (for example, Japanese Utility Model Laid-Open No. 62-75653).

[0007]

However, in the above-mentioned conventional image pickup apparatus, the connector 9 must be provided with a dedicated terminal for determining the cable length. Since the length of the transmission cable 3 can be determined only in steps, there is a problem that it is extremely difficult to apply the transmission cable 3 in a case where the length varies as in the case of the above-described wiring in a home.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides an image pickup apparatus which has a simple structure and which does not deteriorate a video signal even when a CCD image pickup section and a signal processing section are connected by an arbitrary length transmission cable. The purpose is to do.

[0009]

According to a first aspect of the present invention, there is provided an image pickup apparatus comprising a plurality of image pickup devices for picking up an image of a subject, and each of the image pickup devices includes a plurality of image pickup devices. Imaging means for combining the output signal into a dot-sequential signal and outputting the signal; signal processing means for processing the dot-sequential signal to convert the signal into a video signal; and connecting the signal processing means to the imaging means. A signal transmission cable of an arbitrary length, storage means for storing a correction voltage value for correcting a gain of a signal deteriorating according to the length of the signal transmission cable for each predetermined change point, and a length of the signal transmission cable Set
Setting means for setting, and a signal set by the setting means
The change read from the storage means according to the transmission cable length
The signal transmission cable length using the correction voltage value for each
Is calculated, and the calculated correction voltage is calculated.
Gain control amplifier in the signal processing means using the value
It is characterized in Rukoto and control means for varying the gain.

Further, according to the configuration of claim 2, the above-mentioned claim 1 is provided.
In the configuration, the setting unit is an external device.
The signal transmission cable length data set on this device.
It is characterized by comprising receiving means for receiving .

[0011]

[0012]

According to the above construction, according to the construction of the first aspect, the data is read from the storage means in accordance with the length of the signal transmission cable.
Using the corrected voltage value for each change point, the signal transmission cable
The correction voltage value corresponding to the cable length is calculated, and the calculated
The gain control in the signal processing means is performed using the correction voltage value.
Since the gain of the control amplifier is changed, even if the CCD imaging unit and the signal processing unit are connected with a transmission cable of an arbitrary length with a simple configuration, the deterioration of the video signal is eliminated.

Further, according to the configuration of claim 2, it receives from the outside of the apparatus by the receiving means different gain correction voltage value in accordance with the length of signal transmission cable connecting the imaging device and the signal processing means, the gain Signal processing by correction voltage value
Since the gain of the gain control amplifier in the means is changed, even if the CCD imaging unit and the signal processing unit are connected with a transmission cable of an arbitrary length with a simple configuration, the deterioration of the video signal is eliminated.

[0014]

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an imaging apparatus according to a first embodiment of the present invention. In FIG. 1, an image sensor 10 is composed of a CCD, converts an optical image captured by a lens (not shown) into an electric signal for each pixel, and alternately outputs a noise portion and a signal portion containing noise. In the CDS 11, the noise portion of the output signal from the image pickup device 10 is clamped at a constant voltage to remove low-frequency noise, and the noise portion is replaced with the signal portion by sampling and holding the signal portion containing the noise. A signal is generated and the image sensor 1
A dot-sequential video signal from which low-frequency noise superimposed on a signal generated within 0 is removed is output. The dot-sequential video signal is output to the gain control amplifier 13 via the cable 111.

The image pickup device driving section 12 includes the image pickup device 1.
In addition to generating a drive timing pulse for driving 0, a synchronization pulse for a video signal, and the like, it outputs a timing signal such as a horizontal synchronization signal and a vertical synchronization signal to the digital signal processing unit 15 via the cable 112. The image pickup device 10, the CDS 11, and the image pickup device driving section 12
00. Such an imaging unit 100 is already known, and further detailed description will be omitted.

The gain control amplifier 13, the AD converter 14, the digital signal processing unit 15, the video output interface 16, the DA converter 17, the microcomputer 18, the table memory 110, and the setting means 113 are the signal processing means 2
00. Hereinafter, the operation of the signal processing means 200 will be briefly described.

The gain control amplifier 13 varies the gain according to the set voltage output from the DA converter 17.
Such a gain control amplifier 13 can be easily realized by a multiplication circuit. The dot-sequential video signal is subjected to AD
The data is digitized by the converter 14 according to the pixel unit and sent to the digital signal processing unit 15. The correction operation will be described later in detail.

The digital signal processing unit 15 generates a luminance signal and a color signal based on the digitized data, performs white balance processing, gamma correction processing, and the like, and converts the luminance signal and the color signal into a digitized luminance signal and color signal. Output to the video output interface 16. The digital signal processing unit 15 is driven and controlled by a timing signal such as a horizontal synchronizing signal and a vertical synchronizing signal output from the image sensor driving unit 12 and a control signal from the microcomputer 18.

The video output interface 16 is a video interface for outputting a digitized luminance signal and color signal in a format connectable to a personal computer or the like connected to the outside of the image pickup apparatus. , SMPTE RP-125 or IEEE P
It conforms to a format such as 1394. The above is the schematic operation of the signal processing means 200.

Next, the control operation of the gain control amplifier 13 described above, which is the main point of the present application, will be described. As described in the conventional example, the imaging unit 100 and the signal processing unit 2
Due to the cable 111 during 00, the dot-sequential video signal is deteriorated such as the amplitude level is lowered. FIG. 2 shows the relationship between the correction voltage of the DA converter 17 and the length of the cable 111 for correcting the decrease in the amplitude level. The gain correction curve of FIG.
The gain control amplifier 1 is set so that the same image quality as that at the time of reference can be obtained when the cable length is extended by setting the attenuation at 0 V to 0 V.
The correction voltage applied to No. 3 was varied, and the inventors experimentally obtained the correction voltage. This is because the transmission characteristics of such a cable 111 are distributed constant systems, so that purely theoretical analysis is extremely difficult even using the finite element method or the like.

The gain correction curve of FIG. 2 obtained in this manner cannot be described in a function form that can be easily calculated by the microcomputer 18, and there are too many measurement points to store the entire value. Since an excessive storage capacity is required for the table memory 110, a polygonal line approximation is adopted as shown in FIG.

Therefore, in the table memory 110,
Correction voltages h1, h2, and h3 respectively corresponding to three change points l1, l2, and l3 shown in FIG. 3 are stored. The correction voltage hs at an arbitrary point ls between these change points l1, l2, l3 is restored by the algorithm shown in FIG. The processing will be described below with reference to FIG.

First, in step 401, the setting means 1
13, the cable length ls is set. As a method of this setting, for example, the length of the cable 111 is measured by a laser measuring device, a tape measure, or the like, and is input by a dip switch. The setting means may be a fuse ROM or the like.
The next steps 402 to 407 are sorting algorithms that are commonly used.

In step 402, it is determined whether or not ls is equal to or greater than the length l1 corresponding to the first transition point h1, and if it is less than or equal to l1, in step 403, the correction voltage hs is set to hs = ( h1 / l1) ls (1), otherwise step 404 is executed.

In step 404, ls is changed to the next change point h.
It is determined whether or not the length is equal to or greater than the length l2 corresponding to 2; if the length is equal to or less than l2, in step 405, the correction voltage hs is calculated as follows: hs = {(h2-h1) / (l2-l1)} ls (2) is obtained, otherwise step 406 is executed.

In step 406, it is determined whether or not ls is equal to or greater than the length l3 corresponding to the last change point h3. If the length is equal to or less than l3, in step 407, the correction voltage hs is set to hs = ｛ (H3-h2) / (l3-l2)｝ ls (3) In other cases, step 408 is executed.

Step 408 is an exception process in the present algorithm. This is a case where the length of the cable 111 exceeds the upper limit (dynamic range) for restoring the correction voltage hs. Usually, such a case does not exist, but the user mistakes the length ls due to misunderstanding or the like. When set, an error is displayed on the display via the digital signal processing unit 15 and the video output interface 16.

Normally, steps 403, 405, 407
Is performed to restore the correction voltage hs, and the correction voltage hs is output to the DA converter 17 in step 409.
Thus, the restoration of the correction voltage hs is completed.

A series of these processes are executed by the microcomputer 18, and as a result, the point-sequential video signal deteriorated (in other words, attenuated) by the cable 111 can be accurately corrected in the gain control amplifier 13.
In the above description, the number of broken lines in the broken line approximation is set to three, but this number may be any integer of 1 or more.

As described above, according to the present embodiment, the cable 111 connecting the imaging means 100 and the signal processing means 200
Is stored in the table memory 110, and the gain of the gain control amplifier 13 is increased or decreased by a value restored from the data of the change point. And imaging means 1
Even if 00 and the signal processing means 200 are connected, the color signal and the luminance signal output from the video output interface 16 will not be degraded.

Further, since only the changing point of the gain correction curve is stored in the table memory 110, there is an effect that the memory capacity can be reduced and the size can be easily reduced. In addition, since it is possible to correct the error including the quantization error that has been aborted in the AD converter 14 having a finite word length, the digital signal processing unit 15 can reproduce the luminance signal and the chrominance signal with high accuracy.

FIG. 5 is a block diagram of an image pickup apparatus according to a second embodiment of the present invention. In the figure, the imaging means 100, cables 111 and 112, gain control amplifier 13, AD converter 14, digital signal processing unit 15,
The video output interface 16, DA converter 17, and microcomputer 18 are the same as those in the first embodiment, and a description thereof will be omitted. This embodiment is characterized in that a PC interface 19 for communicating with a personal computer 114 is provided inside the signal processing unit 300 instead of the setting unit 113 in the signal processing unit 200 of the first embodiment.

The personal computer 114 is a computer having an image capturing function, and may be a commercially available general-purpose computer. The signal processing means 300 is connected to an extension interface of the personal computer 114.

At the same time, the personal computer 1
Numeral 14 transmits, via the PC interface 19, numerical data corresponding to the length ls of the cable 111 used in the DA converter 17 from outside the imaging apparatus. The specifications of the PC interface 19 include an IIC (Inter IC) bus proposed by Philips,
CCESS. BUSS Industry Group ACCESS. bus or ISA which is a computer extension interface bus.

Now, such a PC interface 19
When the cable length ls is read via, the processing as shown in FIG. 6 is executed. In the figure, first, the cable length ls is measured in the same manner as in the first embodiment, and is input to the personal computer 114 by a user operating keys. As a result, the cable length ls is determined by the signal processing means 3
00 and downloaded to the microcomputer 18 via the PC interface 19 in step 601. Subsequent processing steps 602 to 609 are the same as steps 402 to 409 in the first embodiment, and a description thereof will be omitted.

These series of processes are executed by the microcomputer 18, and as a result, in the gain control amplifier 13, similarly to the first embodiment, the point-sequential video signal deteriorated (in other words, attenuated) by the cable 111 is accurately detected. Can be corrected.

In the present embodiment, only the cable length ls is read from the personal computer 114. However, the algorithm shown in FIG.
May be downloaded to the DA converter 17. Further, without performing the processing as shown in FIG. 6, the gain correction curve shown in FIG. 2 is stored in an internal or external IC card device, hard disk device, optical disk drive, or the like in the personal computer 114, and the correction voltage hs is stored. The data may be directly read and downloaded from the PC interface 19 to the DA converter 17.

As described above, according to the present embodiment, the personal computer 11 that processes a video signal such as a color signal and a luminance signal output from the imaging device outside the imaging device.
In FIG. 4, since the user can freely input the cable length ls used for the process for correcting the deterioration of the dot-sequential video signal due to the length of the cable 111, the signal processing means 300 can be embedded in a wall, for example. In addition to the effect of the first embodiment, there is an additional effect that the device can be provided with intelligent flexibility, in addition to the effect of the first embodiment, even if the cable length is changed during construction or the like.

FIG. 7 is a block diagram of an image pickup apparatus according to the third embodiment of the present invention. In the figure, an imaging unit 100, cables 111 and 112, a digital signal processing unit 15, a video output interface 16, a microcomputer 18,
The PC interface 19 is the same as those in the second embodiment, and the description is omitted. The features of this embodiment are as follows.
In the signal processing unit 300 of the second embodiment, a signal processing unit 40 is used instead of the gain control amplifier 13 and the AD converter 14.
0, an AD converter 40 and a digital gain calculator 4
1 is provided.

The dot-sequential video signal sent from the CDS 11 is input to the AD converter 40 via the cable 111 and is digitized. Note that this AD converter 40
Is higher than the AD converter 14 in the second embodiment and the like by several bits and higher than the resolution of the digital signal processing unit 15 by several bits.

The output of the A / D converter 40 is input to a digital gain calculator 41, multiplied by a gain correction value sent from the microcomputer 18 to make the amplitude constant, and then sent to the digital signal processor 15. The subsequent processing is the first
To the second embodiment, and the process of deriving the gain correction value is the same as that of the second embodiment.

FIG. 8 shows a detailed internal configuration of such a digital gain calculating section. An analog dot sequential video signal is
The data is converted into 16-bit parallel point-sequential video data by the AD converter 40 and input to the digital multiplier 41a. Here, it is multiplied by a 10-bit correction coefficient from the microcomputer 18 and output as 26-bit parallel data, which is truncated or rounded to the upper 10 bits in the shifter 41b and output. The shifter 41b may include a noise shaper.

As a result, the deterioration of the dot-sequential video signal due to the length of the cable 111 can be corrected by pure digital.

As described above, according to the present embodiment, since the gain adjustment is digitized, the analog multiplier constituting the gain control amplifier 13 in the first and second embodiments has an input x. At this time, the output becomes tanh (x), which causes distortion including odd-order harmonics. However, such distortion does not occur because the digital multiplier is used, and offset and drift inherent to the analog circuit are also eliminated. In addition to the effect of the second embodiment, there is a further effect that highly accurate gain correction can be performed.

FIG. 9 is a block diagram of an image pickup apparatus according to a fourth embodiment of the present invention. In the figure, an image sensor 10, a CDS 11, an image sensor driver 12, a cable 1
11 and 112, the gain control amplifier 13, the AD converter 14, the digital signal processing unit 15, the video output interface 16, the DA converter 17, the microcomputer 18, and the PC interface 19 are the same as those in the second embodiment. Omitted. The feature of the present embodiment is that the imaging means 510 is provided with the reference signal generation section 51 and the signal processing means 50 is provided.
0 is provided with the reference level detection unit 52.

The reference signal generator 51 includes a reference signal generator 53 and a signal changeover switch 5 as shown in FIG.
4. It comprises a power rise detector 55 and a timer 56. FIG. 12 shows a signal waveform in a main part of the reference signal generator 51.

The reference signal generator 53 generates a pseudo point sequential video signal, in other words, a kind of reference signal used for automatically detecting the amount of attenuation of the cable 111. The pseudo point sequential video signal is stored in a ROM built in the reference signal generator 53.
While reading numerical values stored in advance in the table at regular intervals, they are combined as analog voltage signals by a digital-to-analog converter or the like.

The power supply rise detector 55 is a circuit for detecting the rise of the power supply voltage. As shown in FIG. 12, the rise of the power supply voltage is delayed by a smoothing capacitor (not shown) interposed in the power supply circuit. Is set to be equal to or less than 1/2 of the steady-state value Vcc.
t, the trigger signal St shown in the figure is detected.
Is output.

The trigger signal St is sent to the timer 56, and as shown in FIG. 12, outputs the enable signal Se which is kept at the "H (high)" level for T seconds from the rising edge of the signal St. Upon receiving the enable signal Se, the signal changeover switch 54 changes the enable signal Se to “
Only when "H", the pseudo-point sequential video signal output from the reference signal generator 53 is output as shown in the dark shaded area, otherwise the dot-sequential video signal output from the CDS 11 is output in the lightly shaded area shown in the figure. Output as follows.

The reference signal generator 51
Are output to the gain control amplifier 13 via the cable 111, and then sent to the reference level detection unit 52. The reference level detecting section 52 includes an integrator 5 as shown in FIG.
7, comparator 58, gate 59, power rising detector 5
10, and a timer 511. FIG. 13 shows a signal waveform in a main portion of the reference level detecting section 52.

The power supply rise detector 510 is a circuit for detecting the rise of the power supply voltage, as in the case of the power supply rise detector 55 of the reference signal generator 51.
As shown in (2), it is detected that the delay of the rise of the power supply voltage due to a smoothing capacitor (not shown) or the like interposed in the power supply circuit has become equal to or higher than a threshold voltage Vu set to 以上 of the steady value Vcc, The illustrated trigger signal St 'is output. It should be noted that this corresponds to the reference signal generator 51.
This is for delaying the output of the trigger signal St 'from the trigger signal St.

This trigger signal St 'is supplied to the timer 511
As shown in FIG. 13, an enable signal Se 'having a "H (high)" level for V seconds from the rising edge of the signal St' is output. This enable signal S
e ′ is sent to the gate 59. These signals St 'and S
The reason for delaying e ′ is to compensate for the propagation delay caused by the cable 111 and to ensure that the integrator 57 described later reliably receives the pseudo-point sequential video signal.

When the power is turned on, the synthesized pseudo-sequential video signal is sent from the imaging means 510 to the gain control amplifier 13 for T seconds as described above. This pseudo point sequential video signal is synthesized so as to change during this time T as shown in FIG. In FIG. 13, the darker the shade, the lower the signal level, and the temporally the signal level gradually increases and decreases.

This pseudo point sequential video signal is sent to an integrator 57, converted into a signal having an amplitude level as shown in FIG. 13, and sent to a comparator 58. The comparator 58 is a kind of window comparator. When the lower limit of the predetermined reference voltage is Vl and the upper limit is Vh, the signal Ch is output when Vh is exceeded, and the signal Cm is output when Vh exceeds Vl.
In the following cases, the signal Cl is output.

These signals Cl, Cm and Ch are supplied to the gate 5
9 and the enable signal Se 'of the timer 511.
Is "H" only when the pulse signal G as shown in FIG.
1, Gm, and Gh are output and sent to the microcomputer 18. These signals Gl, Gm, Gh are signals Cl, Cm, C, respectively.
h is waveform-shaped and the rising edge is differentiated.

When the signal Gl is input, the microcomputer 18 sends a command to the DA converter 17 to increase the gain of the gain control amplifier 13. Conversely, when the signal Gh is input, a command to reduce the gain of the gain control amplifier 13 is sent to the DA converter 17. Thereby, the gain control amplifier 13, the reference level detector 52, the microcomputer 18, the DA converter 1
7 is formed, and the output of the integrator 57 is controlled so as to fall within the reference voltage range (the range of V1 to Vh in FIG. 13).

The response time of this loop is determined by the integrator 5
7 or the rate of change of the output value to the DA converter 17 per pulse in the microcomputer 18 can be changed, and can be settled within the output time V of the enable signal Se ', which is the adjustment time at the time of turning on the power. Can be easily designed to Further, the voltage range between Vl and Vh is set in advance to a range in which the optimum image quality can be obtained on the personal computer 114.

As described above, according to the present embodiment, when the power is turned on, the pseudo-point sequential video signal synthesized and output from the reference signal generator 51 is processed by the reference level detector 52 and sent to the microcomputer 18. From this microcomputer 18
Since the gain of the gain control amplifier 13 can be automatically adjusted by controlling the gain control amplifier 13 via the converter 17, the length of the cable 111 is measured as in the first to third embodiments. There is an additional effect that adjustment is easy because it is not necessary.

In the above embodiment, the cable 111
Is assumed to be an electric wire, but may be an optical fiber. In this case, the CDS 11 is equipped with a light emitting diode or a laser diode, and the gain control amplifier 13 is equipped with a photoelectric conversion element such as a photodiode. If the reason why such a case is assumed is added for reference, degradation of glass optical fiber used in the telecommunications business can be ignored unless it is a long distance, but plastic optical fiber that is considered to be used in homes This is because there is a large loss in the optical fiber.

[0061]

As described above, according to the first aspect of the present invention, the image pickup apparatus according to the first aspect of the present invention has the following features in accordance with the signal transmission cable length.
Using the correction voltage value for each change point read from the storage means
To calculate the correction voltage value corresponding to the signal transmission cable length
Then, using the calculated correction voltage value, the signal processing means
Changes the gain of the gain control amplifier at
Degradation of any length video signals be connected CCD image sensor and a signal processing unit in the transmission cable is that no a simple structure
effective.

Further, since only the correction voltage at the changing point in the correction curve is stored in the storage means, the memory capacity can be reduced and the size can be easily reduced.

Moreover, according to the configuration of claim 2, it receives from the outside of the apparatus by the receiving means different gain correction voltage value in accordance with the length of signal transmission cable connecting the imaging device and the signal processing means, the gain Signal processing by correction voltage value
Since the gain of the gain control amplifier in the means is changed, even if the CCD imaging unit and the signal processing unit are connected with a transmission cable of an arbitrary length with a simple configuration, deterioration of the video signal does not occur .
You.

Further, a signal transmission cable from outside the image pickup apparatus is used.
By allowing the user to freely enter the cable length, for example, signal processing means can be embedded in the wall, and even if the cable length is changed during construction, etc. There is a further effect that it is possible to have.

[0065]

[0066]

[Brief description of the drawings]

FIG. 1 is a block diagram of an imaging apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a correction voltage and a cable length in the embodiment.

FIG. 3 is a line-line approximation of a relationship between a correction voltage and a cable length in the embodiment.

FIG. 4 is a flowchart showing an algorithm for restoring a correction voltage in the embodiment.

FIG. 5 is a block diagram of an imaging device according to a second embodiment of the present invention.

FIG. 6 is a flowchart showing an algorithm for restoring a correction voltage in the embodiment.

FIG. 7 is a block diagram of an imaging device according to a third embodiment of the present invention.

FIG. 8 is a block diagram illustrating a configuration of a digital gain calculator in the embodiment.

FIG. 9 is a block diagram of an imaging device according to a fourth embodiment of the present invention.

FIG. 10 is a block diagram showing a specific configuration of a reference signal generator in the embodiment.

FIG. 11 is a block diagram showing a specific configuration of a reference level detection unit in the embodiment.

FIG. 12 is a waveform chart showing operation waveforms of each unit of the reference signal generation unit in the embodiment.

FIG. 13 is a waveform chart showing operation waveforms of each unit of the reference level detection unit in the embodiment.

FIG. 14 is a schematic block diagram of an imaging device according to a conventional example of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Image sensor 11 CDS 12 Image sensor drive part 13 Gain control amplifier 14 AD converter 15 Digital signal processing part 16 Video output interface 17 DA converter 18 Microcomputer

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04N 5/225-5/232 H04N 5/335 H04N 7/18

Claims (2)

(57) [Claims] 1. An image pickup means comprising a plurality of image pickup devices for picking up an image of a subject, combining an output signal from each of the image pickup devices into a point-sequential signal and outputting the signal, and processing the point-sequential signal. signal processing means for converting the video signal Te, and any length of signal transmission cable for connecting the signal processing means and the imaging means, the gate of the signal deteriorates according to the length of the signal transmission cable
Storage means for storing a correction voltage value for correcting the in for each predetermined change point, and setting means for setting a length of signal transmission cable, respond to a signal transmission cable length set by said setting means
Flip and correction voltage for each change point read from the storage means
Correction voltage corresponding to the signal transmission cable length using the value
Calculate the value and use the corrected voltage value to calculate the signal
Imaging device according to claim Rukoto and a control means for varying the gain of the gain control amplifier in the processing unit. 2. The apparatus according to claim 1, wherein said setting means is an external device.
Receives signal transmission cable length data set by this device
2. The receiving means according to claim 1, further comprising:
An imaging device according to any one of the preceding claims.