JPH08116480A - Image pickup device - Google Patents

Abstract

PURPOSE: To obtain the image pickup device in which a video signal is not deteriorated even when a CCD image pickup section and a signal processing section are connected by a transmission cable of an optional length with simple configuration. CONSTITUTION: A signal from each picture element of an image pickup element 10 is converted into a serial signal at a CDS 11 and fed to a gain control amplifier 13 via a cable 111. An output of the gain control amplifier 13 is converted into a digital signal by an A/D converter 14 and separated into a chrominance signal and a luminance signal by a digital signal processing section 15 and they are outputted. A length of the cable 111 is set to a setting means 113 and a value is read from a table memory 110 by a microcomputer 18 to adjust a gain of the gain control amplifier 13 via a D/A converter 17.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In recent years, development of a system for processing a video signal from a camera using a charge coupled device (hereinafter abbreviated as "CCD") as an image pickup device by a personal computer or a workstation system has been advanced. There is. Due to the multimedia concept led by the Ministry of International Trade and Industry, these are being applied to homes as well, and the range of applications is expanding to home information boards and mobile information terminals in home automation systems.

In consideration of such applications, it is considered that the CCD image pickup section and the signal processing section are separated and only the CCD image pickup section is mounted on the apparatus in order to miniaturize these apparatuses. To be Moreover, in that case, it is expected that the wiring between the CCD imaging unit and the signal processing unit will be variously changed depending on the usage pattern in the home. However, the signal output from the CCD image pickup unit has a high frequency of about 13.5 MHz, and it has been pointed out for a long time that the signal level is deteriorated by this wiring. This signal deterioration due to the difference in wiring length is caused. There is an urgent need to develop technology to correct it 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 image pickup 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. 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 image pickup apparatus configured as described above will be described below.

The video signal picked up by the video camera 1 is
It reaches the input amplifier 7 via the transmission cable 3. The output of the input amplifier 7 is adjusted to have 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 impedance matching of a high frequency video signal and impedance conversion,
Irrelevant to the essential behavior.

By the way, the connector 9 has a plurality of built-in connection terminals, and the length of the transmission cable 3 is preliminarily specified for a plurality of cases except for the terminal through which the video signal is passed.
A terminal corresponding to the specified length is provided, and its terminal is grounded. The cable length determination circuit 5 selects the voltage to be output to the gain control amplifier 6 according to the position of the grounded terminal. This guarantees 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 conventional image pickup apparatus as described above, the connector 9 must be provided with a dedicated terminal for discriminating the cable length, which complicates the configuration and is used. Since the length of the transmission cable 3 is determined only stepwise, there is a problem that it is extremely difficult to apply it when the length is different as in the case of the domestic wiring as described above.

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

[0009]

In order to achieve the above object, the image pickup device of the present invention has a plurality of image pickup devices for picking up an image of a subject in the structure of claim 1, and further comprises An image pickup means for synthesizing the output signal into a dot-sequential signal and outputting the signal, a signal processing means for processing the dot-sequential signal and converting it into a video signal, and a connection means for connecting the signal processing means and the image pickup means. A signal transmission cable of an arbitrary length, a storage unit that stores a predetermined coefficient value that changes according to the length of the signal transmission cable for each predetermined change point, and the above-mentioned storage unit that stores the predetermined coefficient value according to the read value read from the storage unit. Control means for changing the characteristic of the signal processing means, and the read value is the coefficient value restored using the value of the change point.

According to a second aspect of the present invention, the image pickup means is composed of a plurality of image pickup devices for picking up an image of a subject, and the signals output from the respective image pickup devices are combined into a dot-sequential signal and output. A signal processing means for processing the dot-sequential signal and converting it into a video signal; a signal transmission cable of an arbitrary length for connecting the signal processing means and the imaging means;
Receiving means for receiving a coefficient value set from outside the device,
A control means for changing the characteristic of the signal processing means according to the coefficient value is provided, and the coefficient value is changed according to the length of the signal transmission cable.

According to a third aspect of the present invention, the image pickup means is composed of a plurality of image pickup elements for picking up an image of a subject, and the signals output from the respective image pickup elements are combined into a dot-sequential signal and output. An image pickup device comprising a signal processing means for processing the dot-sequential signal and converting it into a video signal, and a signal transmission cable of an arbitrary length for connecting the signal processing means to the image pickup means. Includes generating means for generating a reference signal for correcting characteristic deterioration of the dot-sequential signal due to the length of the signal transmission cable after power is turned on, and the signal processing means determines a signal level of the reference signal to a predetermined level. The detection means outputs a coefficient value that changes in accordance with the result of comparison with the reference value and the control means that changes the characteristics of the signal processing means in accordance with the coefficient value.

[0012]

According to the above-mentioned structure, according to the structure of claim 1, the coefficient value corresponding to the length of the signal transmission cable connecting the image pickup means and the signal processing means is read out from the storage means to be a read value, and this reading is performed. The characteristic of the signal processing means is changed according to the value, and the value at each change point of the coefficient value is stored in the storage means and is restored as a read value. Therefore, the CCD image pickup unit with a simple configuration and a transmission cable of an arbitrary length. Therefore, even if the signal processing unit is connected, the deterioration of the video signal is eliminated.

According to the second aspect of the invention, the coefficient value which differs depending on the length of the signal transmission cable connecting the image pickup means and the signal processing means is received from the outside of the device by the receiving means, and this coefficient value is used. Since the characteristics of the signal processing means are changed, CC can be used with a transmission cable of arbitrary length with a simple configuration.
Even if the D imaging unit and the signal processing unit are connected, the deterioration of the video signal is eliminated.

According to the third aspect of the invention, the generating means included in the image pickup means generates the reference signal for correcting the characteristic deterioration of the dot-sequential signal due to the length of the signal transmission cable after the power is turned on. , The signal level of the reference signal is compared with a predetermined reference value, and the characteristic of the signal processing means is changed according to the result, so that the CCD image pickup section and the signal processing section are connected with a transmission cable of an arbitrary length with a simple configuration. Also, the deterioration of the video signal is eliminated.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an image pickup apparatus according to the first embodiment of the present invention. In the figure, the image pickup device 10 is composed of a CCD, converts an optical image captured by a lens (not shown) into an electric signal in each pixel unit, and alternately outputs a noise part and a signal part containing noise. In the CDS 11, the noise part of the output signal from the image pickup device 10 is clamped to a constant voltage to remove low-frequency noise, and the signal part including noise is sample-held to replace the noise part with the signal part and continuously. Image sensor 1 that generates a signal
A dot-sequential video signal from which low-frequency noise superimposed on the 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.

Further, the image pickup device driving section 12 includes the image pickup device 1
A drive timing pulse for driving 0, a synchronizing pulse for a video signal, and the like are generated, and timing signals such as a horizontal synchronizing signal and a vertical synchronizing signal are output 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 unit 12 are the image pickup means 1
00 is configured. Such an image pickup means 100 is already known, and a detailed description thereof will be omitted.

Now, 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, the setting means 113 are the signal processing means 2.
00 is configured. The outline of the operation of the signal processing means 200 will be described below.

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 AD-corrected by the gain control amplifier 13 after its amplitude is corrected to a constant value.
It is digitized by the converter 14 according to the pixel unit and sent to the digital signal processing unit 15. Note that this correction operation will be described in detail later.

In the digital signal processing section 15, a luminance signal and a color signal are generated based on the digitized data, white balance processing and gamma correction processing are performed, and the digitized luminance signal and color signal are obtained. Output to the video output interface 16. The digital signal processing unit 15 is drive-controlled by timing signals such as a horizontal synchronizing signal and a vertical synchronizing signal output from the image pickup device driving unit 12 and a control signal from the microcomputer 18.

The video output interface 16 is a video interface for outputting the 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. , RP-125 of SMPTE or P of IEEE
It conforms to a format such as 1394. The above is the general operation of the signal processing means 200.

Now, the control operation of the above-described gain control amplifier 13, which is the main point of the present application, will be described. As described in the conventional example, the image pickup means 100 and the signal processing means 2
The cable 111 between 00 causes deterioration of the dot-sequential video signal such as a decrease in amplitude level. The relationship between the correction voltage of the DA converter 17 and the length of the cable 111 for correcting this decrease in the amplitude level is given by FIG. The gain correction curve in Fig. 2 shows that the cable length is 0m.
The gain control amplifier 1 is set so that the image quality similar to that at the reference time is obtained when the cable length is extended by setting the attenuation at 0V to 0V.
This is experimentally obtained by the inventors by changing the correction voltage applied to No. 3. This is because such a transfer characteristic of the cable 111 is a distributed constant system, so that a pure theoretical analysis is extremely difficult even if the finite element method or the like is used.

The gain correction curve of FIG. 2 obtained in this way 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, the polygonal line approximation is adopted as shown in FIG.

Therefore, in the table memory 110,
The correction voltages h1, h2, h3 respectively corresponding to the three change points l1, l2, l3 shown in FIG. 3 are stored. The correction voltage hs at an arbitrary point ls between these changing points 11, 12, and 13 is restored by the algorithm shown in FIG. The process will be described below with reference to FIG.

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

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

In step 404, Is is the next change point h.
It is determined whether or not the length is greater than or equal to the length l2 corresponding to 2, and if the length is less than or equal to l2, the correction voltage hs is set to hs = {(h2-h1) / (l2-l1)} ls in step 405. (2) is obtained, and in other cases, step 406 is executed.

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

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

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

These series of processes are executed by the microcomputer 18, and as a result, the gain control amplifier 13 can accurately correct the dot-sequential video signal deteriorated (in other words, attenuated) by the cable 111.
Although the number of broken lines approximated to the broken line is three in the above description, this number may be any integer of 1 or more.

As described above, according to this embodiment, the cable 111 connecting the image pickup 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 / decreased by the value restored from the data of this change point. Therefore, a cable having a simple configuration and an arbitrary length is used. And image pickup means 1
00 and the signal processing means 200, the deterioration of the color signal and the luminance signal output from the video output interface 16 is eliminated.

Further, since only the change points of the gain correction curve are stored in the table memory 110, there is an effect that the capacity of the memory can be small and the size can be easily reduced. Further, since the quantization error cut off by the AD converter 14 having a finite word length can be corrected, the digital signal processing unit 15 can reproduce the luminance signal and the color signal with high accuracy.

Now, FIG. 5 is a block diagram of an image pickup apparatus according to the second embodiment of the present invention. In the figure, the image pickup means 100, cables 111 and 112, gain control amplifier 13, AD converter 14, digital signal processing unit 15,
The video output interface 16, the DA converter 17, and the microcomputer 18 are the same as those in the first embodiment, and their explanations are omitted. A feature of this embodiment is that a PC interface 19 for communicating with the personal computer 114 is provided in the signal processing means 300 in place of the setting means 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 general-purpose commercially available product. The signal processing means 300 is connected to the extension interface of the personal computer 114.

At the same time, the personal computer 1
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 the outside of the image pickup apparatus. The specifications of this PC interface 19 are IIC (Inter IC) bus, A proposed by Philips.
CCESS. bus Industry Group's proposal ACCESS. The bus may be ISA, which is a computer expansion interface bus, or the like.

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 the user operates the keys to input it to the personal computer 114. As a result, the cable length ls is determined by the signal processing means 3
00, and is 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 the 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, the dot-sequential video signal deteriorated (in other words, attenuated) by the cable 111 is exactly as in the first embodiment. Can be corrected to.

In this embodiment, only the cable length ls is read from the personal computer 114, but the algorithm shown in FIG. 6 is executed by the personal computer 114 to directly output the correction voltage hs to the PC interface 19.
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 IC card device, a hard disk device, an optical disk drive or the like which is built in or attached to the personal computer 114, and the correction voltage hs is stored. It may be read directly and downloaded from the PC interface 19 to the DA converter 17.

As described above, according to this embodiment, the personal computer 11 that processes video signals such as color signals and luminance signals output from the image pickup device outside the image pickup device.
By allowing the user to freely input the cable length ls used in the process for correcting the deterioration of the dot-sequential video signal due to the length of the cable 111, for example, the signal processing means 300 is embedded in the wall. In addition to the effect of the first embodiment, there is a further effect that the device can be provided with intelligent flexibility because the cable length can be immediately dealt with even during the construction or the like.

Now, FIG. 7 is a block diagram of an image pickup apparatus in the third embodiment of the present invention. In the figure, an image pickup means 100, cables 111 and 112, a digital signal processing section 15, a video output interface 16, a microcomputer 18,
The PC interface 19 is the same as those in the second embodiment, and the explanation is omitted. The feature of this embodiment is that
Instead of the gain control amplifier 13 and the AD converter 14 in the signal processing unit 300 of the second embodiment, the signal processing means 40 is used.
0 AD converter 40 and digital gain calculator 4 inside
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 digitized. In addition, this AD converter 40
Is a product having a high resolution of several bits as compared with the AD converter 14 in the second embodiment and the like, and a resolution of several bits higher than the resolution of the digital signal processing unit 15.

The output of the AD converter 40 is input to the digital gain calculator 41, multiplied by the gain correction value sent from the microcomputer 18 to fix the amplitude constant, and then sent to the digital signal processor 15. Subsequent processing is the first
~ The same as the second embodiment, and the gain correction value derivation process is also the same as that of the second embodiment.

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

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

As described above, according to the present embodiment, by digitizing the gain adjustment, the analog multiplier constituting the gain control amplifier 13 in the first and second embodiments has the input as x. At this time, the output becomes tanh (x), and distortion including odd harmonics is generated. However, since the digital multiplier is used, such distortion does not occur, and the offset and drift peculiar 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 is possible.

Now, FIG. 9 is a block diagram of an image pickup apparatus according to the fourth embodiment of the present invention. In the figure, the image sensor 10, the CDS 11, the image sensor driver 12, the 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, and a description thereof will be given. Omit it. The feature of this embodiment is that the image pickup 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 detecting unit 52.

The reference signal generator 51 includes a reference signal generator 53 and a signal changeover switch 5 as shown in FIG.
4, a power supply rising detector 55, and a timer 56. FIG. 12 shows a signal waveform in the main part of the reference signal generating section 51.

The reference signal generator 53 generates a pseudo dot sequential video signal, in other words, a kind of reference signal used for automatically detecting the attenuation amount of the cable 111. This pseudo dot sequential video signal is stored in the ROM incorporated in the reference signal generator 53.
The numerical values stored in advance in the table are read out at regular intervals and are combined as an analog voltage signal by a digital-analog converter or the like.

The power supply rising detector 55 is a circuit for detecting the rising of the power supply voltage, and the rising of the power supply voltage is delayed by a smoothing capacitor (not shown) interposed in the power supply circuit as shown in FIG. Threshold voltage V which is set to 1/2 or less of the steady value Vcc
When the trigger signal St shown in FIG.
Is output.

The trigger signal St is sent to the timer 56, and as shown in FIG. 12, the enable signal Se which is kept at "H (high)" level for T seconds is output 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 dot sequential video signal output from the reference signal generator 53 is output as shown in the shaded area in the figure. In other cases, the dot sequential image signal output from the CDS 11 is output in the shaded area as shown in the figure. To output.

Now, in this way, the reference signal generator 51
The pseudo dot-sequential video signal and the dot-sequential video signal output from the are input to the gain control amplifier 13 via the cable 111, and then sent to the reference level detection unit 52. This reference level detecting section 52, as shown in FIG.
7, comparator 58, gate 59, power supply rising detector 5
10 and a timer 511. FIG. 13 shows a signal waveform in the main part 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, like the power supply rise detector 55 of the reference signal generator 51, as shown in FIG.
As shown in (4), it is detected that the power supply voltage is delayed by the smoothing capacitor (not shown) interposed in the power supply circuit or the like, and is detected as being equal to or higher than the threshold voltage Vu set to 1/2 or more of the steady value Vcc. The illustrated trigger signal St 'is output. It should be noted that this is the reference signal generator 51.
This is for delaying the output of the trigger signal St ′ from the trigger signal St of.

This trigger signal St 'is supplied to the timer 511.
Then, as shown in FIG. 13, the enable signal Se ′ that is maintained at the “H (high)” level for V seconds is output from the rising edge of the signal St ′. 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, which will be described later, receives the pseudo dot sequential video signal.

When the power is turned on, the synthesized pseudo dot sequential video signal is sent from the image pickup means 510 to the gain control amplifier 13 for T seconds as described above. This pseudo dot sequential video signal is synthesized so as to change during this time T as shown in FIG. Note that, in FIG. 13, the darker the shade, the lower the signal level, and the temporally higher and lower signal level.

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

These signals Cl, Cm and Ch are applied to the gate 5
9, the enable signal Se ′ of the timer 511 is sent.
Pulse signal G as shown in FIG. 13 only when is "H"
It outputs l, Gm and Gh and sends them to the microcomputer 18. These signals Gl, Gm and Gh are signals Cl, Cm and C, respectively.
The waveform of h is 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, if the signal Gh is input, a command is sent to the DA converter 17 to reduce the gain of the gain control amplifier 13. As a result, the gain control amplifier 13, the reference level detection unit 52, the microcomputer 18, the DA converter 1
A negative feedback control loop composed of 7 is formed, and the output of the integrator 57 is controlled so as to fall within the reference voltage range (range of V1 to Vh in FIG. 13).

The response time of this loop depends on the integrator 5
It can be changed by adjusting the gain of 7 or the rate of change of the output value to the DA converter 17 per one pulse in the microcomputer 18, and it can be changed within the output time V of the enable signal Se 'which is the adjustment time when the power is turned on. Easy to design. Further, the voltage range between Vl and Vh is preset to a range in which the optimum image quality is obtained on the personal computer 114.

As described above, according to this embodiment, when the power is turned on, the pseudo level sequential video signals synthesized and output from the reference signal generating section 51 are processed by the reference level detecting section 52 and sent to the microcomputer 18. , From this microcomputer 18 DA
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 a further effect that adjustment is easy because it is not necessary.

In the above embodiment, the cable 111
Is based on 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, the deterioration can be ignored in the glass optical fiber used in the communication business unless the distance is long, but the deterioration of the plastic optical fiber that is considered to be used at home is considered. This is because the optical fiber has a large loss.

[0061]

As described above, in the image pickup device of the present invention, according to the structure of claim 1, the coefficient value corresponding to the length of the signal transmission cable connecting the image pickup means and the signal processing means is read from the storage means. However, the read value is used as a read value, the characteristic of the signal processing means is changed by the read value, and the value at each change point of the coefficient value is stored in the storage means and is restored as the read value. Even if the CCD image pickup unit and the signal processing unit are connected with a long transmission cable, the image signal does not deteriorate, so a highly flexible image capturing computer system,
This has the effect of configuring a home information board, a portable information terminal, or the like.

Further, since only the change points on the curve of the coefficient values are stored in the storage means, there is an effect that the capacity of the memory can be small and the size can be easily reduced.

According to the second aspect of the present invention, the receiving means receives from the outside of the apparatus a coefficient value that differs depending on the length of the signal transmission cable connecting the image pickup means and the signal processing means, and the coefficient value is used. Since the characteristics of the signal processing means are changed, CC can be used with a transmission cable of arbitrary length with a simple configuration.
Even if the D imaging unit and the signal processing unit are connected to each other, the deterioration of the video signal is eliminated, so that there is an effect that a highly flexible image capturing computer system, a home information panel, a portable information terminal, and the like can be configured.

Further, by allowing the user to freely input the coefficient value from the outside of the image pickup apparatus, for example, even if the signal processing means is embedded in the wall and the cable length is changed during the construction or the like. Since it can be dealt with immediately, it has the additional effect of providing intelligent flexibility.

According to the third aspect of the present invention, the reference signal for correcting the characteristic deterioration of the dot-sequential signal due to the length of the signal transmission cable is generated after the power is turned on from the generation means included in the image pickup means. , The signal level of the reference signal is compared with a predetermined reference value, and the characteristic of the signal processing means is changed according to the result, so that the CCD image pickup section and the signal processing section are connected with a transmission cable of an arbitrary length with a simple configuration. Since there is no deterioration of the video signal, there is an effect that a highly flexible image capturing computer system, a home information panel, a portable information terminal, and the like can be configured.

Further, when the power is turned on, the reference signal which is synthesized and output from the generating means can be processed by the detecting means and the gain of the signal processing means can be adjusted by the control means. Since there is no need to measure, there is a further effect that adjustment is easy.

[Brief description of drawings]

FIG. 1 is a block diagram of an image pickup 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 example.

FIG. 3 is a broken-line approximation diagram showing the relationship between the correction voltage and the cable length in the example.

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

FIG. 5 is a block diagram of an image pickup apparatus 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 image pickup apparatus according to a third embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of a digital gain calculation section in the embodiment.

FIG. 9 is a block diagram of an image pickup apparatus according to a fourth embodiment of the present invention.

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

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

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

FIG. 13 is a waveform diagram showing operation waveforms of respective parts of the reference level detection unit in the embodiment.

FIG. 14 is a schematic block diagram of an image pickup apparatus in a conventional example of the present invention.

[Explanation of symbols]

 10 image sensor 11 CDS 12 image sensor driver 13 gain control amplifier 14 AD converter 15 digital signal processor 16 video output interface 17 DA converter 18 microcomputer

Claims (3)

[Claims] 1. An image pickup device comprising a plurality of image pickup devices for picking up an image of a subject, and combining the signals outputted from the respective image pickup devices into a dot-sequential signal and outputting the dot-sequential signal, and processing the dot-sequential signal. Signal processing means for converting the signal processing means into a video signal, a signal transmission cable of an arbitrary length for connecting the signal processing means and the image pickup means, and a predetermined coefficient value that changes according to the length of the signal transmission cable. The read value is the value of the change point, and the storage means stores the change point at each predetermined change point, and the control means that changes the characteristic of the signal processing means according to the read value read from the storage means. An imaging device, wherein the coefficient value is restored by using the above-mentioned coefficient value. 2. An image pickup means comprising a plurality of image pickup devices for picking up an image of a subject, and combining the signals output from the respective image pickup devices into a dot-sequential signal and outputting the signal, and processing the dot-sequential signal. Signal processing means for converting the signal processing means to a video signal, a signal transmission cable of an arbitrary length for connecting the signal processing means and the image pickup means, and a receiving means for receiving a coefficient value set from outside the device, An image pickup apparatus comprising: a control unit that changes a characteristic of the signal processing unit according to a numerical value; and the coefficient value that changes according to a length of the signal transmission cable. 3. An image pickup means comprising a plurality of image pickup elements for picking up an image of a subject, and combining the signals outputted from the respective image pickup elements into a dot-sequential signal and outputting the signal, and processing the dot-sequential signal. And a signal transmission cable of an arbitrary length for connecting the signal processing means and the image pickup means, wherein the image pickup means includes The signal processing means includes a generating means for generating a reference signal for correcting the characteristic deterioration of the dot-sequential signal due to the length of the signal transmission cable, and the signal processing means compares the signal level of the reference signal with a predetermined reference value. An image pickup apparatus comprising: a detection unit that outputs a coefficient value that changes according to a result; and a control unit that changes the characteristic of the signal processing unit according to the coefficient value.