JP2628992B2 - Endoscope imaging device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging apparatus for an endoscope in which a camera head and a signal processing unit are configured separately, and both are connected by a cable.

[Conventional technology]

Such an imaging device is disclosed in Japanese Patent Application No.
An endoscope device described in JP-A-60-225368 already exists. This device incorporates a solid-state imaging device such as a charge-coupled device (CCD) at the tip of an endoscope to image a target. The signal processing unit is provided separately from the endoscope, usually in the light source device.
The driving pulse of the solid-state imaging device is transmitted from the driving pulse generator provided in the signal processing unit to the solid-state imaging device at the distal end of the endoscope via a signal line in a cable connecting the endoscope main body and the light source device. . Similarly, the output of the solid-state imaging device is transmitted to a signal processing unit via a signal line in the endoscope, where it is subjected to signal processing such as clamping, sample & hold, and the like.
An image signal of the object is generated.

Here, since the drive pulse is a high-frequency signal, if transmitted through a long signal line, the waveform will be distorted during transmission and will not be a short wave when supplied to the solid-state imaging device. The element cannot be driven. Therefore, it is necessary to provide a matching circuit for compensating the waveform distortion in advance on the signal processing unit side, and to supply a driving pulse to the solid-state imaging device via the matching circuit.

Also, the output of the solid-state imaging device is delayed while being transmitted to the signal processing unit, and the output of the solid-state imaging device when input to the signal processing unit is delayed with respect to the timing of the drive pulse. In order to compensate for this, various timings of signal processing are delayed with respect to the timing of the drive pulse according to the type of endoscope (the length of the signal line).

[Problems to be solved by the invention]

In this conventional device, in order to connect a plurality of endoscopes in common to the same signal processing unit (light source device), it is necessary to provide matching circuits as many as the number of endoscopes connected to the signal processing unit. There is a disadvantage that the signal processing unit becomes large.
Also, since the amplitude of the drive pulse is quite large, the influence of electromagnetic waves radiated from the signal line during transmission from the signal processing unit to the solid-state imaging device on other devices cannot be ignored.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide a camera head and a signal processing unit in a separate endoscope imaging apparatus, in which a delay during signal transmission between the two and deterioration of waveforms are caused. The advantage is to compensate for the adverse effect by the simple configuration regardless of the difference in the length of the signal line.

[Means for solving the problem]

The imaging device for an endoscope according to the present invention includes a camera head 10 and a signal processing unit 12 connected via a cable 14, and the camera head 10 includes a solid-state imaging device 20 and an output of a first voltage-controlled oscillator 30. A drive pulse generator 22 that generates a drive pulse for the solid-state image sensor at a timing according to the signal processing unit 12 that processes the output of the solid-state image sensor 20 supplied from the camera head 10 via the cable 14 Processing circuit
34, a timing generator 36 for generating various timing pulses of the signal processing circuit 34, and a second voltage controlled oscillator serving as a timing reference of the timing generator 36
38, input signal and cable of timing generator 36
The phase difference between the input signal of the drive pulse generator 22 supplied from the camera head 10 via the cable 14 or the phase difference between the timing pulse and the drive pulse supplied from the camera head 10 via the cable 14 becomes zero. The phase comparator 42 controls the voltage applied to the second voltage controlled oscillator 38 as described above.

[Action]

According to the endoscope imaging apparatus of the present invention, the phase delay amount of the signal from the camera head 10 to the signal processing unit 12 is detected by the phase comparator 42, and the phase of the timing pulse is controlled by the output of the phase comparator 42. Signal processing circuit
The processing timing of 34 is always appropriately controlled. In addition, since the driving pulse of the solid-state imaging device 20 is not transmitted from the signal processing unit 12 but is generated in the camera head 10, the deterioration of the waveform during the transmission of the driving pulse is compensated in the signal processing unit 12. There is no need to provide a matching circuit for performing the processing, and the configuration of the signal processing unit 12 is simplified.

〔Example〕

An embodiment of an endoscope imaging apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of the first embodiment. The imaging device for an endoscope according to the first embodiment includes a camera head 10 and a signal processing unit 12, both of which are connected by a cable 14.

The camera head 10 includes a solid-state imaging device (here, a charge-coupled device: CCD) 20 and a drive pulse generator 22 that generates a drive pulse for the CCD 20. The drive pulse generator 22 includes a frequency divider for dividing the output pulse of the first voltage controlled oscillator 30 in the signal processing unit 12. The input signal of the drive pulse generator 22 is transmitted to the signal processing unit 12 via the signal line 16 in the cable 14.

The signal processing unit 12 includes a first voltage-controlled oscillator (VCO) 30 that generates a clock pulse for giving a reference timing of the drive pulse generator 22 and a potentiometer that generates a control voltage for determining an oscillation frequency of the first VCO 30. The output of the first VCO 30 is supplied to the drive pulse generator 22 via the cable 14. Further, the signal processing unit 12 includes a signal processing circuit 34 that performs signal processing such as clamping, sample and hold, and the like on the output signal of the CCD 20, a timing generator 36 that generates various timing pulses of the signal processing circuit 34, and a timing generator 36. A second VCO 38 for generating a clock pulse for providing a reference timing, a delay circuit 40 for delaying the output of the second VCO 38 and supplying it to a timing generator 36, and an input (delay circuit) of the timing generator 36
40) and the input of the drive pulse generator 22 transmitted from the camera head 10 via the signal line 16 (the output of the first VCO 30 reciprocated to the camera head 10 via the cable 14). The phase comparator 42 includes a phase comparator 42 to be detected and a level adjuster 44 that supplies a control voltage corresponding to the output of the phase comparator 42 to the second VCO 38. The output of the signal processing circuit 34 is supplied to a display unit (not shown). Timing generator 36 is second
Of the VCO 38 is divided. The level adjuster 44 is an operational amplifier that converts the output of the phase comparator 42 to the control voltage of the second VCO 38.

According to this embodiment, first, the control voltage applied to the first VCO 30 is finely adjusted by the potentiometer 32 so that the oscillating frequencies of the first and second VCOs 30 and 38 are made substantially equal. Drive pulse generator 22 based on the output of first VCO 30
Is supplied to the CCD 20, and the CCD 20 is driven.

The signal output from the CCD 20 is subjected to signal processing such as clamping, sample & hold, and the like in the signal processing circuit 34, and an image signal of the object is generated. The timing pulse that determines the timing of these various signal processings is the second VCO 38
Are generated from the timing generator 36 on the basis of the output. Here, the oscillation frequencies of the first and second VCOs 30 and 38 are almost the same, but as described above, the camera head 10
And the signal processing unit 12 are connected via a cable 14,
Since the output of the first VCO 30 is transmitted to the drive pulse generator 22 via the cable 14, the drive timing of the CCD 20 and the various timings of the signal processing circuit 34 do not match. Further, since the output of the CCD 20 is also input to the signal processing circuit 34 via the cable 14, the output of the CCD 20 input to the signal processing circuit 30 is delayed with respect to the phase of the drive pulse. Therefore, unless some kind of phase control means is used,
Various timings of the signal processing circuit 34 are shifted.

In this embodiment, a driving pulse generator in the camera head 10 is used.
The input of 22 (the output of the first VCO 30 in the signal processing unit 12 supplied to the camera head 10 via the cable 14) is connected to the signal line 16
The signal is supplied to the signal processing unit 12 via the, and the phase difference between the signal and the output of the second VCO 38 in the signal processing unit 12 is detected by the phase comparator 42. If the length of the signal line 16 from the input terminal of the drive pulse generator 22 to the input terminal of the phase comparator 42 is equal to the length of the signal line from the output terminal of the CCD 20 to the input terminal of the signal processing circuit 34 , The output of the CCD 20 is the signal processing circuit 34
Phase delay received before transmission to the phase comparator
It will be detected at 42. The second VCO 38 is a delay circuit 4
0, together with the phase comparator 42, constitutes a phase control (PLL) circuit. The delay circuit 40 is a circuit for adjusting the phase as much as possible when a phase difference that cannot be completely adjusted by the VCO 38 occurs, and may be omitted if the VCO 38 has a function of adjusting the phase. With this PLL circuit, the signals of the two input terminals of the phase comparator 42 have the same phase and frequency.

Therefore, the timing pulse is transmitted to the signal processing circuit 34 from the camera head 10 via the cable 14 and then transmitted to the signal processing circuit 34.
The output signal of the CCD 20 has the same phase as that of the output signal of the D20, and the output signal of the CCD 20 is processed at a correct timing. Furthermore, even if the length of the cable 14 changes and the delay time during signal transmission changes, such as in the case of an endoscope as described above, the signal processing unit 12 can cope with the same configuration and does not require adjustment. There is also the effect that it is.

Further, in the first embodiment, since the drive pulse generator 22 is provided in the camera head 10, it is not necessary to transmit the drive pulse via the cable 14, so that the matching circuit for compensating the waveform distortion in advance is subjected to signal processing. There is no need to provide it in the unit 12, and there is no need to consider the effect of electromagnetic waves radiated by the driving pulse during transmission.

The connection position of the delay circuit 40 is not limited to the output of the VCO 38,
Various changes are possible. This modification is shown in FIG.
(B) and (c) show. In FIG. 2A, the output of the VCO 38 is directly input to the timing generator 36, but the delay circuit 4 is provided in the feedback path from the VCO 38 to the phase comparator 42.
0 is connected. In FIG. 2B, the output of the VCO 30, which is an input to the drive pulse generator 22 supplied from the camera head 10 via the signal line 16, is supplied to the phase comparator 42 via the delay circuit 40. In FIG. 2C, the output signal of the CCD 20 is supplied to the signal processing circuit 34 via the delay circuit 40.
The same effects as in the first embodiment can be obtained in the modifications shown in FIGS. 2 (a) to 2 (c).

Next, a second embodiment of the endoscope imaging apparatus according to the present invention will be described. FIG. 3 is a block diagram of the second embodiment.
In the second embodiment, the same parts as those in the first embodiment are denoted by the same reference numerals. The second embodiment consists of the same components as the first embodiment, but the connection is slightly different. The phase comparator 42 detects the phase difference between the drive pulse and the timing pulse instead of detecting the phase difference between the input of the timing generator 36 and the input of the drive pulse generator 22. That is, a part of the output of the drive pulse generator 22 is supplied to the signal processing unit via the signal line 16.
The signal is transmitted to a second input terminal of the phase comparator. A part of the output of the timing generator 36 is supplied to a second input terminal of the phase comparator 42.

According to the second embodiment as well, the timing pulse output from the timing generator 36 is applied to the camera head 10.
The phase of the output signal of the CCD 20 after being transmitted to the signal processing circuit 34 via the cable 14 coincides with the phase of the signal, and the output signal of the CCD 20 is subjected to signal processing at a correct timing. Further, in this embodiment, the VCO 30 is transmitted from the camera head 10 to the signal processing unit 12.
Since the divided drive pulse is transmitted instead of the output of (i), the divided phases can be matched. The drive pulse is VC
Since the frequency is lower than the output of O30, there is also an advantage that waveform deterioration during transmission is small.

FIGS. 4 (a), 4 (b) and 4 (c) show a modification of the second embodiment relating to the connection position of the delay circuit 40. FIG. In FIG. 4A, the output of the timing generator 36 is input to the phase comparator 42 via the delay circuit 40. In FIG. 4B, the output of the drive pulse generation circuit 22 supplied from the camera head 10 via the signal line 16 is input to the phase comparator 42 via the delay circuit 40. In FIG. 4C, the output of the CCD 20 is input to the signal processing circuit 34 via the delay circuit 40. According to these modifications, the same effects as those of the second embodiment can be obtained.

The present invention is not limited to the above-described embodiments, and can be variously modified without departing from the gist thereof.

〔The invention's effect〕

As described above, according to the present invention, the amount of signal transmission delay from the camera head to the signal processing unit is detected by the phase comparator in the signal processing unit, and the timing of the signal processing circuit that performs signal processing on the output of the solid-state imaging device. Is controlled by the output of the phase comparator, thereby providing an endoscope imaging apparatus having a simple configuration capable of compensating for a delay in signal transmission by a cable between the camera head and the signal processing unit. further,
According to the imaging device for an endoscope of the present invention, since the driving pulse of the solid-state imaging device is not transmitted from the signal processing unit but is generated in the camera head, the driving pulse is being transmitted to the signal processing unit. Therefore, it is not necessary to provide a matching circuit for compensating for the deterioration of the waveform, and the configuration of the signal processing unit is simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a first embodiment of an endoscope imaging apparatus according to the present invention, and FIGS. 2 (a), (b),
(C) is a block diagram of a modification of the first embodiment, FIG. 3 is a block diagram showing the configuration of an endoscope imaging apparatus according to a second embodiment of the present invention, and FIGS. 4 (a) and 4 (b). , (C) is a block diagram of a modification of the second embodiment. 20: solid-state imaging device (CCD), 22: driving pulse generator, 30, 38: voltage-controlled oscillator (VCO), 34: signal processing circuit, 36: timing generator, 42: phase comparator.

Claims (7)

(57) [Claims] 1. An endoscope imaging apparatus in which a camera head and a signal processing unit are connected via a cable, wherein the camera head includes: a solid-state imaging device; and a driving pulse generator that generates a driving pulse for the solid-state imaging device. Means, the signal processing unit comprising: a first oscillator for supplying a reference pulse to the drive pulse generating means; a signal processing means for processing an output of the solid-state imaging device; and a timing pulse for the signal processing means. Means for supplying a reference pulse to the timing pulse generating means; and a pulse output from the first oscillator and reciprocated to the camera head via the cable and input to the vibration processing unit. , The phase difference between the timing pulse and the output of the solid-state imaging device supplied from the camera head via the cable becomes zero. Endoscopic imaging apparatus characterized by comprising a phase control means for controlling the phase of sea urchin said timing pulse. 2. The driving pulse generating means includes a pulse generator for generating a driving pulse by dividing the output of the first oscillator, and the timing pulse generating means dividing the output of the second oscillator. A timing generator that generates a timing pulse by using a signal generator that transmits an input of the pulse generator to the signal processing unit via the cable; and an input of the timing generator and the signal transmission. A phase comparator that detects a phase difference from an input of the pulse generator transmitted from the camera head via a unit, and controls a phase of the second oscillator according to a detection result. The imaging device for an endoscope according to claim 1, wherein: 3. A delay circuit according to claim 1, wherein a delay circuit is connected between an output of said first oscillator or said second oscillator and said phase control means.
Item 14. The endoscope image pickup device according to Item 1. 4. The endoscope according to claim 1, wherein a delay circuit is connected between an output of said solid-state imaging device and said signal processing means. Imaging device. 5. An endoscope imaging apparatus in which a camera head and a signal processing unit are connected via a cable, wherein the camera head includes a solid-state imaging device and a first reference pulse supplied from the signal processing unit. And a driving pulse generating means having a pulse generator for generating a driving pulse for the solid-state imaging device by dividing the frequency of the signal. The signal processing section generates a first reference pulse supplied to the driving pulse generating means. A first oscillator that performs processing, a signal processing unit that processes an output of the solid-state imaging device, a second oscillator that generates a second reference pulse, and a timing that generates a timing pulse by dividing the second reference pulse Timing pulse generating means having a generator, detecting a phase difference between the timing pulse and a drive pulse transmitted from the camera head via the cable A phase control unit that controls a phase of the second oscillator according to a detection result, based on a drive pulse input to the signal processing unit via the cable, the timing pulse and the signal via the cable. An imaging apparatus for an endoscope, wherein a phase of the timing pulse is controlled so that a phase difference from a driving pulse transmitted from a camera head becomes zero. 6. An endoscope according to claim 5, wherein a delay circuit is connected between an output of said first oscillator or said second oscillator and said phase control means. Imaging device. 7. An endoscope imaging apparatus according to claim 5, wherein a delay circuit is connected between an output of said solid-state imaging device and said signal processing means.