JP3499968B2 - Electronic endoscope device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic endoscope having a solid-state image pickup device for picking up an endoscopic observation image, which is detachably connected to a video processor. The present invention relates to an endoscope device. 2. Description of the Related Art In general, in an electronic endoscope apparatus, a sample and hold circuit for extracting a video signal from an image pickup signal output from a solid-state image pickup device of the electronic endoscope, and the sample and hold circuit and the solid state A video processor is provided with a timing generator and the like for generating a drive pulse for driving the image sensor in synchronization with the image sensor. A driving pulse output from a timing generator of a video processor is sent to a solid-state imaging device of an electronic endoscope, and is stored in each pixel portion of the solid-state imaging device by exposure. The transferred charges are sequentially transferred by the driving pulse. FIGS. 4 to 6 show the state of such charge transfer performed in the solid-state image pickup device. The circles indicate whether or not a numeral is entered or not. Shows the charge of. In the solid-state image pickup device, when a high level VIH voltage is applied to the φS gate, as shown in FIG. Are stored in (A). Subsequently, as shown in FIG. 5, when a low level VIL voltage is applied to the φS gate, the portion (A) below the electrode becomes a shallow potential well,
The charge stored in the deep potential well of the portion (A) under the electrode when the voltage of IH is applied is changed by the potential of the charge implantation layer previously stored by the ion implantation method.
Move to the next part (B). Subsequently, as shown in FIG.
When a voltage of VIH is applied to the gate, the portion (C) under the electrode becomes a deep potential well, so that the charge accumulated in the deep potential well of the portion (B) when the voltage of VIL is applied is reduced. It moves to the next part (C) by the potential of the embedded layer. As described above, by inputting the high-level and low-level voltages VIH and VIL pulses to the φS gate at appropriate timing, the charge is changed from (A) to (B).
And (B) to (C). As described above, in order to perform a large number of charge transfer operations in a certain period, it is necessary to shorten the pulse cycle of the voltages VIH and VIL applied to the φS gate, but this naturally has a limit. For example, assuming that the cycle of the pulse of VIH and VIL is specified at a maximum of 10 [MHZ], when the duty is 50%, VIH = 50 [ns],
VIL = 50 [ns] is the guaranteed operation range. If the pulse width is not satisfied, that is, the duty ratio of the pulses of the voltages VIH and VIL is not good, for example, the duty ratio is too large and the VIL period is 5
0 [ns], from the state shown in FIG.
For example, as shown in FIGS. 7 and 8, the charges accumulated in the portion (C) are not transferred to the adjacent depletion layer but are mixed with the charges in the portion (A), so that an accurate signal output can be obtained. And image quality is degraded. The duty ratio of the driving pulse differs for each video processor due to variations in the characteristics of integrated circuits (ICs) and peripheral elements used for each video processor. Therefore, the image quality varies depending on the video processor. Become. Accordingly, the present invention is to obtain an optimum duty ratio for each video processor for a solid-state image sensor driving pulse, and to obtain good and stable image quality without charge transfer failure in the solid-state image sensor. It is an object of the present invention to provide an electronic endoscope apparatus capable of performing the above. [0014] In order to achieve the above object, an electronic endoscope apparatus according to the present invention comprises an electronic endoscope having a solid-state image pickup device for picking up an endoscopic observation image. In an electronic endoscope apparatus detachably connected to a video processor, a duty ratio varying means for varying a duty ratio of a driving pulse for driving the solid-state imaging device is provided in the video processor. Embodiments will be described with reference to the drawings. FIG. 1 shows an overall configuration of an electronic endoscope apparatus according to an embodiment of the present invention. The image forming position of a subject by an objective optical system 3 provided at the tip of an insertion section 2 of the electronic endoscope 1 is shown in FIG. , Charge-coupled device (C
A solid-state image pickup device 4 made of CD) is arranged, and an endoscope observation image is picked up. Reference numeral 5 denotes a light guide fiber bundle for transmitting illumination light for illuminating the observation range. The connector section 6 of the electronic endoscope 1 detachably connected to the video processor 10 includes a solid-state image pickup device 4
A connection contact for connecting various signal lines between the light guide fiber bundle and the video processor 10, an input end 5a of the light guide fiber bundle 5, a delay setting circuit 7 described later, and the like are arranged. The video processor 10 also serves as an illumination light source device. Illumination light from a light source lamp 11 is incident on an incident end 5 a of a light guide fiber bundle 5 of the electronic endoscope 1. In the middle of the incident optical path, a three-color rotating filter 12 having three color filters of red (R), green (G) and blue (B) is arranged so as to rotate at a constant speed. Thus, illumination light of each color of red, green, and blue is sequentially incident on the light guide fiber bundle 5 with a time lag. In the sample-and-hold circuit 14, a video signal is extracted from the image signal output from the solid-state image sensor 4, and the video signal is subjected to predetermined processing by a video signal processing circuit and sent to an external output device such as a monitor 20. The image is output and the endoscope observation image is displayed on the monitor 20 or the like. From the timing generator 16, the sample and hold timing of the sample and hold circuit 14 and the drive pulses φP and φS for driving the solid-state image pickup device 4.
Are output in synchronization with each other. When the solid-state image sensor 4 is connected to the video processor 10 via the connector section 6, the horizontal drive pulse φS of the solid-state image sensor 4
The operation is delayed by a time corresponding to the length of the signal line inside the electronic endoscope 0 and the signal line inside the electronic endoscope 1. Therefore, in order to synchronize the imaging signal input from the solid-state imaging device 4 to the sample-and-hold circuit 14 with the sampling in the sample-and-hold circuit 14,
A delay circuit 17 is inserted and connected in the middle of a signal line from the timing generator 16 to the solid-state imaging device 4. With respect to the delay circuit 17, the delay setting circuit 7 disposed in the connector section 6 on the electronic endoscope 1 side outputs
Delay information suitable for the electronic endoscope 1 is input. In this manner, the image signal input to the sample and hold circuit 14 and the sampling pulse thereof are properly synchronized with the electronic endoscope 1 connected to the video processor 10. In the middle of a signal line for transmitting a driving pulse from the timing generator 16 to the solid-state image pickup device 4,
A duty ratio variable circuit 18 for changing the duty ratio of the horizontal drive pulse φS is inserted and connected. In this embodiment, the variable duty ratio circuit 18 is connected to the solid-state image pickup device 4 from the delay circuit 17. Conversely, the variable duty ratio circuit 18 is connected to the timing generator 16 from the delay circuit 17. You may. FIG. 2 shows an example of a circuit configuration of the duty ratio variable circuit 18, in which two amplifiers 181, 18
2, a variable resistor 183 is connected in series, and the other end of the capacitor 184 connected to the connection between the amplifier 182 and the variable resistor 183 at the subsequent stage is grounded. Therefore, the duty ratio variable circuit 18 supplies the horizontal drive pulse φS of the sample hold circuit 14
Is input, the fall of the pulse can be varied by adjusting the resistance value of the variable resistor 183. However, the duty ratio variable circuit 18 of the present invention is not limited as long as it can change the duty ratio, such as changing the rising of the pulse, or changing both the rising and falling of the pulse. A circuit may be used. As described above, the timing generator 16
Since the variable duty ratio circuit 18 is inserted and connected in the middle of the signal line for transmitting the drive pulse from the device to the solid-state imaging device 4, as shown in FIG. The ratio is for example 2
Even in the case of 5% or 60%, the duty ratio can always be adjusted to the optimal 50%. If the optimum duty ratio is not 50%, adjustment may be made in accordance with the optimum duty ratio. This duty ratio adjustment is performed by connecting an electronic endoscope as a reference to each video processor 10 at a final adjustment site of a factory where the video processor 10 is manufactured. Therefore, it is not necessary to perform any adjustment operation in the subsequent endoscopic examination. According to the present invention, the duty ratio varying means for varying the duty ratio of the drive pulse for driving the solid-state imaging device is provided in the video processor, so that the optimum Since a duty ratio can be obtained, a good and stable image quality can be obtained by eliminating charge transfer failure in the solid-state imaging device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an overall configuration of an embodiment of the present invention. FIG. 2 is a circuit diagram showing an example of a duty ratio variable circuit according to the embodiment of the present invention. FIG. 3 is a time chart illustrating an operation of the duty ratio variable circuit according to the embodiment of the present invention. FIG. 4 is a schematic diagram illustrating a charge transfer state in the solid-state imaging device. FIG. 5 is a schematic diagram illustrating a charge transfer state in the solid-state imaging device. FIG. 6 is a schematic diagram showing a charge transfer state in the solid-state imaging device. FIG. 7 is a schematic diagram showing a state of charge transfer failure in the solid-state imaging device. FIG. 8 is a schematic diagram illustrating a state of charge transfer failure in the solid-state imaging device. [Description of Signs] 4 Solid-state imaging device 10 Video processor 18 Duty ratio variable circuit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-132280 (JP, A) JP-A-61-273079 (JP, A) JP-A-62-254215 (JP, A) JP-A-2- 249527 (JP, A) JP-A-4-38093 (JP, A) JP-A-6-105807 (JP, A) JP-B-4-6306 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) A61B 1/00-1/32 G02B 23/24

Claims (1)

(57) [Claim 1] An electronic endoscope apparatus in which an electronic endoscope having a solid-state imaging device for imaging an endoscope observation image is detachably connected to a video processor. An electronic endoscope apparatus, wherein a duty ratio varying unit for varying a duty ratio of a driving pulse for driving a solid-state imaging device is provided in the video processor.