JPH01270842A - Electronic endoscope device - Google Patents

Abstract

PURPOSE:To project a picture, which is always optimum and has a high observing effect, by forming the changing means of picture element determining causes in correspondence to the change of the type of a solid image pick-up element and the change of a signal band to accompany selective signal processing such as the enlarging and reducing, etc., of the picture. CONSTITUTION:A means is provided to change the frequency of the driving signal or driving system of the solid image pick-up element in correspondence to the discriminating information of the type of the solid image pick-up element, which is sent to a signal processing unit, to execute interpolation so that the picture angle of monitor display can be equal regardless of the type of the solid image pick-up element and to change the setting value of a circuit to be the causes of the picture quality determination in correspondence to the change of the signal band in an upper limit to accompany the function of picture enlarging processing and slave picture processing, etc. Thus, even when the solid image pick-up element is different or the enlarging or reducing of the picture is executed, in correspondence to these conditions, the picture quality determining causes are set to the desired value and the picture of the high observing effect can be obtained.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an electronic endoscope apparatus provided with means for changing image quality determining factors according to the type of solid-state image sensor and screen enlargement/reduction processing. [Conventional technology] In recent years, solids such as COD! Imaging neck devices using Ill elementary images as imaging means are widely used. Also, in endoscopes, solid-state image sensors such as COD are used with W.
An i-image means is provided at the distal end of the insertion section, and generates a drive signal for driving the solid-state image sensor, and also converts the subject signal obtained from the solid-state image sensor into a television signal. I! 2. Description of the Related Art An electronic endoscope device has been proposed in which a screen of a subject is displayed on a monitor via the device, and a subject image displayed on the monitor is observed. In an endoscope using the above-mentioned solid-state B element, as disclosed in Japanese Patent Laid-Open No. 61-179129, an endoscope with different characteristics specific to the solid-state Rl element can be processed by a single signal processing. The device and monitor are shared and used, and for this purpose a means of storing various condition information such as the type of endoscope, white balance, angle of view of the solid-state image sensor, and sensitivity of the solid-state UD image element is provided. By connecting the connector to the connector receiver on the signal processing device side, the condition information is read by the reading device of the signal processing device, and the information (hereinafter referred to as Scope IQ) is transmitted to the corresponding IT, 11@ section. It is designed to automatically set various conditions. In addition, it has been proposed that the signal processing device has capabilities such as enlarged display and small screen output, and efforts are being made to improve the viewing effect. [Problems to be Solved by the Invention] Therefore, when changing the frequency of the drive signal depending on the type of prisoner fti image element, the upper limit of the video signal band naturally changes. Furthermore, when signal processing such as screen enlargement processing or child screen processing is performed, the upper limit of the signal band changes. Therefore, despite changes in the upper limit of the signal band, image quality determining factors (enhancement frequency, enhancement level, coring level, LPF characteristics, contrast, etc.)
If this is not changed, there will be cases where the image on the monitor will not provide the desired viewing effect. For example, the upper limit of the band for standard definition display is 3MHz, and the enhancement frequency is set to 2.
If set to M l - I Z, the Il'lX effect can be improved, but if the upper limit of the band becomes 1.5 MHz by performing expansion processing without changing the enhancement frequency, it will not be sufficient. No effect can be obtained. Furthermore, when the type of COD changes and the frequency of the drive signal is lowered, a strong aliasing signal will appear unless the cutoff frequency of LP'F before Δ/D conversion is lowered. The present invention has been made in view of the above points,
The purpose of the present invention is to provide an electronic endoscope device that always displays an optimal image with high observation effect even when the upper limit of the video signal band changes due to the type of solid-state image element or the function of the signal processing device. [Means and effects for solving the problem] The present invention includes changing the frequency or drive method of the drive signal of the solid-state Ia image element in accordance with the type discrimination information of the solid-state image sensor sent to the signal processing device; Solid monitor display angle! Means for changing setting values of a circuit that is a factor determining image quality in response to changes in the upper limit of a signal band due to functions such as interpolation processing, image enlargement processing, and child screen processing to make the image equal regardless of the type of elementary image; is the provision. This gives the solid i
Even if the pixel elements are different, or even if the image is enlarged or reduced, the image quality determining factors are set to desirable values accordingly, so that an image with high viewing effects can be obtained. [Example] The present invention will be specifically described below with reference to the drawings. Figures 1 to 15 relate to one embodiment of the present invention;
The figure is a block diagram of the electronic endoscopy all device according to the first embodiment, FIG. 2 is a schematic perspective view showing the entire apparatus of the first embodiment, and FIG. 3 is a diagram showing the types of solid-state image sensors used in the first embodiment. The perspective view, Figure 4 is C0Dl! Figure 5 is a diagram of the configuration of the LPF circuit, Figure 6 is a schematic diagram of the frequency characteristics of the LPF circuit, Figure 7 is the diagram of the digital signal processing circuit, Figure 8 is the diagram of the digital signal processing circuit. Schematic diagram of frequency characteristics of signal processing circuit, No. 9
10 and 11 are diagrams explaining the operation of the contour correction circuit. FIG. 12 is a schematic diagram of the frequency characteristics of the contour correction circuit, and FIGS. 13, 14, and 15. The figure is an explanatory diagram of the operation of the nonlinear circuit. As shown in FIG. 2, the electronic endoscope device 1 of the first embodiment includes an electronic endoscope (hereinafter referred to as electronic scope) 2A, and an external fiberscope equipped with a 28km TV camera 3 is a fiberscope with a camera 2C. And these scope 2A,
It is composed of a signal processing device 4 that performs 2G signal processing, a light source device 5 that supplies illumination light to both these scopes 2A and 2C, and a display monitor 6 that is connected to the signal processing device 4 by a cable (not shown). be done. Both scopes 2A, 2G (or 2B) have an elongated insertion section 7, and an operation section 8 is connected to the rear end of the insertion section 7. In addition, each insertion section 7 transmits illumination light.
In the electronic scope 2A, this light guide 9 is inserted through a universal cord 11 extending from the operating section 8, and its incident end reaches a light guide connector 12. Further, in the fiber scope 2B, the light guide cable 13 extending from the operating section 8 is inserted, and the incident end of the light guide 9 reaches the light guide connector 14. The light guide connectors 12, 14 can be connected to the connector receiver 15 of the light source device 5, as shown by the dashed line, and illumination light is supplied by being connected. The illumination light supplied to the light guide funectors 12 and 14 is transmitted and emitted from the output end face disposed on the distal end side of the insertion section 7 to the subject side via the light distribution lens. The object illuminated by the illumination light is imaged on its focal plane by the objective lens 17 attached to the tip of the insertion section 7. In the electronic scope 2A, the C0D 18 is arranged on the focal plane, and in the fiber scope 2B, the incident end surface of the image guide 19 is arranged. The C0D 18 is connected to a signal transmission cable, and a signal connector 21 is attached to the cable inserted through the universal cord 11 so that it can be connected to a signal connector receiver 22 of the signal processing device 4. On the other hand, in the fiber scope 2B, an optical image is transmitted to the eyepiece 23 by the image guide 19, and the TV camera 3 attached to the eyepiece 23 focuses it on the CCD 24 via the imaging lens in the TV camera 3. It is so that you can image it. The CCD 24 in this TV camera 3 has a signal code of 26
The signal connector 27 attached to the tip of this cable can be connected to the signal connector receiver 22 of the signal processing device 4. The C0D18.24 used in the electronic scope 2A and the TV camera 3 is, for example, as shown in FIG. 3(a), depending on the type of the electronic scope 2A or the TV camera 3.
There are various types as shown in (b) and (c). In other words, in Fig. 3(a), the number of pixels is large (the angle of view is large)! CGD 18a (or 24
a), and the figure (b) shows the II image plane 28b (CCr) 18b (or 24b) with a small number of pixels (small angle of view).
The figure (c) shows that the shape of the image transport plane 28c is the same as that in the figure (a).
, shows C0D18G (or 24C) different from the square shown in (b). FIG. 1 shows the configuration of an electronic endoscope device according to an embodiment, which can be used with scopes 2A and 2G having CODs having different numbers of pixels and shapes of image carrying planes as shown in FIG. 3 above. When the electronic scope 2A (or scope 2C) is connected to the signal processing device 4 via the signal connector 21 <27) and the signal connector receiver 22, the scope discrimination circuit 29 is installed in the electronic scope 2Δ (2C). Scope ID
31 (CCD18.24 is shown in Figure 3 (a), (b),
(c), etc.) is detected and transmitted to the controller 32. The controller 32 receives this

[Press to select and preset various circuits. Below, C0D18.24 is shown in Figure 3 with scope ID 31 (
The explanation will focus on examples of type a). When the controller 32 detects, via the scope discrimination circuit 29, that the electronic scope is of the type CCD 18a, 24a (hereinafter, 24a will not be particularly described), the controller 32 detects the COD drive circuit 33 as the type (a) type of COD. be selected so that it can be driven. As shown in FIG. 4, the drive circuit 33 includes, for example, a CCD 18i (ia, b
, c) respectively 20MHz, 10MHz, 4MH
It is composed of drive circuits 33a, 33b, and 33c that are driven by Z, and a switch SW1 that selects these, and when the (a) type CCD 18a (with a large number of pixels) is used, the 20MHz drive circuit 53a is the drive circuit from the controller 32. It is selected by a selection signal and drives this CCD 18a. The output signal from the CCD 18a is amplified by a preamplifier 41 and input to a sample hold circuit 42. The sample and hold circuit 42 receives timing pulses from the controller 32 to match the 20 MHz drive output. The output of the sample hold circuit 42 is input to an LPF circuit 43. The LPF" circuit 43 includes a plurality of LPFs as shown in FIG.
, for example, LPFs 43a, 43b, 43c and these LPFs
43i. Each L
As shown in FIG. 6, the frequency characteristics of the PF43t are set so that its cutoff frequency is equal to or lower than the Nyquist frequency of the COD output signal. Therefore, 20MHz
For the output signal from the drive, the switch SW2 is switched by a PF selection signal from the controller 32, and the LPF 43a with a cutoff frequency of 10 MH2 is selected. The output of the LPF circuit 43 is input to a contour correction circuit 44. The output of the contour correction circuit 44 is input to a γ correction circuit 47 via an AGC circuit 45 and a white balance circuit 46. In addition to correction using preset values, the γ correction circuit 47 can manually change the γ curve and switch the contrast by sending a signal from the operation panel 48 to the controller 32 via the CPIJ 49. The output of the γ correction circuit 47 is input to the LPF circuit 51. The LPF circuit 51 is configured similarly to the LPF circuit 43 (see FIG. 5), and is installed as an antialiasing filter (filter for eliminating aliasing noise) before A/D conversion. The frequency characteristics of the LPF circuit 51 are also selected by the controller 32, and the cutoff frequency is selected to be 10 MHz or less for an output signal driven at 20 MHz. The output of the LPF circuit 51 is converted to A/D by the A/D converter 52.
converted. The clock applied to the A/D converter 52 is selected by the controllers 1 to 32, and for output No. 3 driven at 20 MHz, A/D conversion is performed with a clock of approximately 10 Mt-fz. Become. The signal that has been converted into digital data by the A/D converter 52 is stored in the -H memory 53 and read out. The functions of this memory 53 include a time base collector and image freezing. The output of the memory 53 is input to a digital signal processing circuit 54. The digital signal processing circuit 54 includes, for example, the seventh
As shown in the figure, there is an enlarged display function that uniformly enlarges, for example, 1.5 times, 2 times, and 3 times.
Second. Third enlargement circuit 54a. 54b, 54c and a switch S for switching the signal line
W3. Consists of SW4. The input signal is sent to the expansion circuit 54
It is extended on the time axis by being enlarged. That is, when a chevron-shaped signal as shown on the left side of FIG. 7 is input, it is expanded on the time axis by the enlarging circuit 54i, resulting in the signal waveform shown on the right side of FIG. Therefore, the band of the output signal changes as shown in FIG. In other words, the band of the input signal changes depending on the expansion rate of the expansion circuit 541 to a signal band divided by the expansion rate. The output of the digital signal processing circuit 54 is D/A converted by a D/A converter 55 and input to an LPF circuit 56. The LPF circuit 56 also has the same configuration as the LPF circuit 43, and its frequency characteristics can be switched by the controller 32. However, this LPF
Each of the cutoff frequencies of the internal components of the circuit 56 is determined by the COD drive frequency and the digital signal processing circuit 54.
It is determined by a combination of the frequency characteristics of the expansion circuit 54i. The output of the LPF circuit 56 is input to a contour correction circuit 57. As shown in FIG. 9, the contour correction circuit 57 includes a first delay means 60, a switch 61 for selecting this delay amount, a second delay means 62, a switch 63 for selecting this delay amount, and an addition circuit. 64, 65, 66, amplifiers 67, 68, and a nonlinear circuit 69. The input signal and the first.
The signals delayed by the second delay means 60, 62 are added in an adder 64. Thereafter, the signal which has been multiplied by 11/2 by the amplifier 67 and delayed by the first delay means 60 is added by the adder 65 to produce a signal with a waveform as shown in FIG. 9(a), which is multiplied by 1 by the amplifier 68. Ru. The amplification factor α can be arbitrarily set using an emphasis level setting signal from the controller 32. The output of the amplifier 68 is added to the output of the delay means 6o by a nonlinear circuit 69, which will be described in detail later, in an adder 66, and becomes the output of the contour correction circuit 57. Here, the first
The output of the d-delaying means 60 with a short delay time is sent to the switch 6.
As the output becomes longer delay time,
Connected to c, d, and e terminals. The same applies to the output of the second delay means 62, and the a+ of the switch 63
, br , cl , d/ , the second connected to el
The delay times of the delay means 62 are a, b, C, d, respectively.
Same as e. Therefore, when switch 61 selects a, switch 63 selects a'. The switches 61 and 63 can be switched by a delay suspension setting signal from the controller 32. FIG. 10 shows the difference in output signals depending on the amount of delay. For the signal shown in Figure 10 (A), Figure 10 (B) shows a case where the amount of delay is medium; when the upper limit of the signal band becomes low, the signal shown in Figure 10 (C) can be changed by increasing the amount of delay. Set the emphasis frequency low,
When the upper limit of the signal band becomes high, the emphasis frequency can be set high by reducing the amount of delay as shown in FIG. 10(D). Therefore, by changing the emphasized frequency as indicated by B, C, and D in FIG. 12(a) according to the first limit of the signal band, the frequency characteristics of the signal processing system can be changed as shown in FIG. 12(a).
B, C, and D of C) can be used. This eliminates unnaturalness in the image and improves the viewing effect. (Here, B, C, and D correspond to B, C, and D in FIG. 10.) Next, regarding the amplifier 68, see FIG. 9(a).
The contour enhancement level can be adjusted by arbitrarily setting the amplification factor α of the differential signal shown in FIG. FIG. 11 shows the difference in output signals depending on the emphasis level. Regarding the signal in Fig. 11 (A), Fig. 11 (Bo) shows a case where the emphasis level is medium, Fig. 11 (C゛) shows a case where the emphasis level is strong, and Fig. 11 (0°) shows a case where the emphasis level is strong. This is an example in which the emphasis level is weakened. In the present invention, the strength of this emphasis level is also switched according to the signal band. As mentioned earlier, the factors that cause the signal band to change are changes in the COD drive frequency and image enlargement processing, but especially when image enlargement processing is performed, image blurring occurs as a result of interpolation. In this case, it is desirable to increase the level of contour enhancement as contour correction. Therefore, when the signal band becomes lower due to image enlargement processing, not only the edge enhancement frequency is lowered, but also the edge enhancement level is correspondingly increased. FIG. 12(b) shows the frequency characteristics of the contour correction circuit in this case. E in the figure shows a case where the emphasis frequency is lowered and the emphasis level is made stronger, and F in the same figure shows a case where the emphasis frequency is higher and the emphasis level is weaker. Note that B' corresponds to Bo in FIG. Furthermore, by changing the emphasis frequency as described above, as shown by F' in FIG. 12(d), frequency components higher than the limit of the signal band-limited by the LPF are not emphasized. In addition, the observation effect can be enhanced by rapidly changing the strong 3 frequency by inputting from the operation panel 4B to obtain a frequency characteristic as shown in G' of FIG. 12(d). As mentioned above, the output of the amplifier 6B is input to the booster 66 via the nonlinear circuit 69.
9 will be explained. The six nonlinear circuits are shown in Figure 13(a).
The output characteristics are as shown in . Therefore, as shown in FIG. 14, low level signals can be suppressed. By placing this circuit in the position shown in Figure 9 (2),
It is possible to suppress low-level edge enhancement components such as those generated by noise components contained in the input signal, and it is possible to reduce the roughness of the screen. FIG. 15 is an explanatory diagram of the operation. Assume that the contour correction circuit 57 receives a signal including noise (indicated by diagonal lines) as shown in FIG. 15(a). At this time, the input of the nonlinear circuit 69 is as shown in FIG. 15(b).
The signal is as shown in , which also includes a component that emphasizes the noise component. This signal is connected to the nonlinear circuit 69 in FIG.
The low level signal is suppressed by the input/output characteristics shown in C), and the signal is shaped into a signal as shown in FIG. 15(d). Therefore, the output obtained by adding the original signal and the emphasized signal in the adder 66 is as shown in FIG. 15(e), in which the emphasized signal with respect to the noise component is suppressed. Furthermore, this nonlinear circuit 6
9 can also be used to change the emphasis level, so an explanation will be added here. By changing the slope of the linear portion of the input/output characteristics shown in FIG. 13(a) as shown by the dotted line in FIG. 13(b), it can also function as the amplifier circuit 68. Also, the same figure (
It may also be combined with changing the suppression level as shown in C). Therefore, instead of changing the amplification factor of the amplifier 68 in response to a change in the upper limit of the signal band, it is possible to change the emphasis level by changing the characteristics of the nonlinear circuit 69 as described above. Furthermore, the nonlinear circuit 69 may be configured by a large number of polygonal lines. The output of the contour correction circuit 57 reaches the monitor 6 via a buffer (not shown) and can be observed as an image. The basic configuration of the contour correction circuit 57 and the contour correction circuit 44 provided at the previous stage are the same, and their operations are also the same. In the above description, for convenience of explanation, the COD drive circuit 33
Although the writing is limited to the driving frequency of the LPF circuits 43, 51, 56, the frequency characteristics of the LPF (431, etc.) of the yarns configured, and the enlargement magnification of the image enlargement processing circuit 54, these values can be set arbitrarily. It may be possible to do so. Furthermore, the number of constituent elements that can be switched by the controller 32 is not limited to three types, and the number of constituent elements is arbitrary. The present invention can be applied both to a built-in color filter type in which a color filter such as a mosaic color filter is provided on the front side of the COD serving as a color imaging means, and to a frame sequential type in which no color filter is provided. Furthermore, the present invention is not limited to signal processing for enlargement, but can also be applied to signal processing for reduction, and can also be applied to cases in which a child screen is superimposed on a parent screen. [Effects of the Invention] As described above, according to the present invention, even when the signal processing system has a signal processing system in which the upper limit of the signal band is changed for changes in the drive frequency of COD and image enlargement processing, etc. Since a means is provided to change the image quality determining factors in response to changes in the upper limit of the signal band, even when various signal processing is performed on various COD outputs, the optimal environmental condition is always maintained for the signal. You can obtain images with good quality.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1 to 15 relate to one embodiment of the present invention.
The figure is a configuration diagram of an electronic endoscope device according to one embodiment, and the second figure is a block diagram of an electronic endoscope device according to one embodiment.
FIG. 3 is a perspective view showing the type of solid-state imaging device used in the first example; FIG. 4 is a configuration diagram of a COD drive circuit; FIG. 5 is a configuration diagram of an LPF circuit. 6 is a characteristic diagram showing the outline of the frequency characteristics of the LPF circuit, FIG. 7 is a configuration diagram of the digital signal processing circuit, and FIG. 8 is a characteristic diagram showing the outline of the frequency characteristics of the digital signal processing circuit. FIG. 9 is a configuration diagram of the contour correction circuit, FIGS. 10 and 11 are operation explanatory diagrams of the contour correction circuit, FIG. 12 is a characteristic diagram showing the outline of the frequency characteristics of the contour correction circuit, and FIGS. 14 and 15 are explanatory diagrams of the operation of the nonlinear circuit. 1...Electronic endoscope device 2A...Electronic scope 2
B...Fiber scope 2C...External fiber scope with camera 3...
TV camera 4...Signal processing device 5...Light source device 6...Monitor 18.24...CCD
33...CCO drive circuit 42...Digital signal processing circuit 43.51.56...LPF (low pass filter)
44.57... Contour correction circuit Figure 3 Old a (24a) (C) Figure 11 Figure 13 Figure 14

Claims (1)

[Scope of Claim] An electronic endoscope device having an imaging means using a solid-state image sensor and a signal processing system that converts a signal read from the solid-state image sensor into a predetermined video signal, comprising: 1. An electronic endoscope apparatus, comprising means for changing image quality determining factors in accordance with a change in type and a change in signal band due to selective signal processing such as image enlargement/reduction.