JP2012075807A - Electronic endoscope apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic endoscope apparatus which can automatically perform the optimal enhancing processing.SOLUTION: The electronic endoscope apparatus which includes an electronic endoscope which outputs an endoscope image as an image signal, a monitor, and a processor for an electronic endoscope which processes an image signal and forms a video signal which can be displayed on a monitor, includes a distance measuring instrument which measures the distance between a monitor and an observer located in the front surface of the monitor, wherein the processor for an electronic endoscope includes a signal processing circuit which forms an image from an image signal and performs an enhancing processing centering on the predetermined spatial frequency of the image, wherein the signal processing circuit alters the predetermined spatial frequency based on the distance measured by the distance measuring instrument.

Description

  The present invention relates to an electronic endoscope apparatus that displays an endoscopic image output from an electronic endoscope on a monitor, and more particularly to an electronic endoscope that displays an enhanced endoscopic image on a monitor. Relates to the device.

  An electronic endoscope having a built-in objective optical system and an image sensor at the distal end of an insertion tube of the endoscope, and a video signal that can be displayed on a monitor by processing a video signal output from the electronic endoscope An electronic endoscope apparatus including an electronic endoscope processor is widely used for diagnosis in a body cavity or the like.

  In an electronic endoscope apparatus, in order to make it easy to see an endoscopic image displayed on a monitor, image processing such as enhancement processing (contour emphasis processing) is performed by an electronic endoscope processor (Patent Document 1). ). In general, the enhancement process is a process of band-emphasizing the spatial frequency of an endoscopic image. Specifically, according to the number of CCD pixels, noise level, etc. of a connected electronic endoscope, a mask of a spatial filter is used. The calculation coefficient is changed, and the spatial frequency for enhancement processing is changed (Patent Document 2).

JP 7-313447 A JP 2005-103325 A

  Even if the image output from the electronic endoscope is blurred, an image with high sharpness can be obtained by performing optimal enhancement processing with the processor for electronic endoscope. However, when accurate enhancement processing is not performed (that is, when the spatial frequency to be emphasized is incorrect), a desired image cannot be obtained, and the image becomes unnatural or has increased noise. There is a problem that. Further, in order to obtain a desired image, an operation for searching for an optimum spatial frequency to be emphasized (that is, an operation for adjusting enhancement) is required. However, it is necessary to perform such an operation while operating the endoscope. This is bothersome for the surgeon. As a result, the patient is forced to make a long-term diagnosis.

  The present invention has been made to solve the above problems. That is, an object of the present invention is to provide an electronic endoscope apparatus that can automatically perform optimum enhancement processing.

  In order to achieve the above object, an electronic endoscope apparatus according to the present invention includes an electronic endoscope that outputs an endoscopic image as a video signal, a monitor, and a video signal that can process the video signal and display it on the monitor. An electronic endoscope device including a processor for generating an electronic endoscope, and a distance measuring means for measuring a distance between a monitor and an observer positioned in front of the monitor. The processor includes a signal processing circuit that generates an image from the video signal and performs enhancement processing around a predetermined spatial frequency of the image, and the signal processing circuit has a predetermined spatial frequency based on the distance measured by the distance measuring unit. It is characterized by changing.

  With such a configuration, optimal enhancement processing is performed according to the distance between the monitor and the observer (surgeon), and the surgeon always looks at the image with the optimal enhancement processing while viewing the endoscope. It becomes possible to operate. Further, since the operator does not need to perform another operation while operating the endoscope, the operator can concentrate on the operation of the endoscope, and as a result, the diagnosis time is shortened.

  In addition, the signal processing circuit measures the reference spatial frequency determined so that optimum enhancement processing is performed when the distance between the monitor and the observer is a predetermined reference distance, the maximum spatial frequency that can be resolved by the monitor, and distance measurement. The predetermined spatial frequency may be changed based on the distance measured by the means. With such a configuration, it is possible to obtain a spatial frequency necessary for performing the optimum enhancement processing by a simple calculation.

  The distance measuring means includes a plurality of sensor units, and each of the plurality of sensor units measures a distance between a human sensor that detects whether or not an observer exists and a monitor and the observer. It is preferable to provide a distance sensor.

  The signal processing circuit may be configured to change a predetermined spatial frequency based on the minimum distance among the distances between the monitor and the observer measured by the plurality of sensor units. With such a configuration, even when a plurality of observers are detected by the distance measuring unit, it is possible to perform the optimum enhancement process for the observer closest to the monitor.

  The human sensor is preferably a heat ray sensor, and the distance measuring sensor is preferably an ultrasonic sensor.

  As described above, according to the present invention, an electronic endoscope apparatus that can automatically perform optimal enhancement processing is realized.

FIG. 1 is a block diagram of an electronic endoscope apparatus according to an embodiment of the present invention. FIG. 2 is a diagram for explaining human visual characteristics, which is a prerequisite for explaining the enhancement processing executed by the electronic endoscope apparatus of the present embodiment. FIG. 3 is a diagram for explaining enhancement processing executed in the electronic endoscope apparatus according to the present embodiment. FIG. 4 is a flowchart of the automatic enhancement process executed by the system controller of the present embodiment. FIG. 5 is a block diagram illustrating the configuration of the distance measuring sensor according to the present embodiment. FIG. 6 is a flowchart of a distance measurement routine executed in the automatic enhancement process of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram of the electronic endoscope apparatus of the present embodiment. As shown in FIG. 1, the electronic endoscope apparatus 1 of the present embodiment includes an electronic endoscope 100, an electronic endoscope processor 200, and a monitor 300.

  The processor 200 includes a system controller 202 and a timing controller 204. The system controller 202 controls each element constituting the electronic endoscope apparatus 1. The timing controller 204 outputs a clock pulse for adjusting the signal processing timing to various circuits in the electronic endoscope apparatus 1.

  The lamp 208 emits white light after being started by the lamp power igniter 206. As the lamp 208, a high-intensity lamp such as a xenon lamp, a halogen lamp, a mercury lamp, or a metal halide lamp is suitable. Illumination light emitted from the lamp 208 is collected by the condenser lens 210, is limited to an appropriate amount of light through the diaphragm 212, and enters an incident end of an LCB (light carrying bundle) 102.

  A motor 214 is mechanically connected to the diaphragm 212 via a transmission mechanism such as an arm or a gear (not shown). The motor 214 is a DC motor, for example, and is driven under the control of the driver 216. The diaphragm 212 is configured such that the opening degree is changed by driving the motor 214 in order to make the image displayed on the monitor 300 have an appropriate brightness, and the amount of illumination light emitted from the lamp 208 is changed to the opening degree. Restrict according to The appropriate reference for the brightness of the image is changed according to the brightness adjustment operation of the front panel 218 by the operator. Note that the dimming circuit that controls the brightness by controlling the driver 216 is a well-known circuit and is omitted in this specification.

  The illumination light incident on the incident end of the LCB 102 propagates by repeating total reflection in the LCB 102. The illumination light that has propagated through the LCB 102 is emitted from the exit end of the LCB 102 disposed at the tip of the electronic scope 100. The illumination light emitted from the exit end of the LCB 102 illuminates the subject via the light distribution lens 104. The reflected light from the subject forms an optical image at each pixel on the light receiving surface of the solid-state image sensor 108 via the objective lens 106.

  The solid-state image sensor 108 is a single-plate color CMOS (Complementary Metal Oxide Semiconductor) image sensor in which various filters such as an IR (InfraRed) cut filter 108a and a Bayer array color filter 108b are arranged on the front surface of the light receiving surface. The optical image formed by the pixel is accumulated as a charge corresponding to the amount of light, and converted into an imaging signal corresponding to each of R, G, and B colors. The converted imaging signal is input to the driver signal processing circuit 112, and after being subjected to processing such as AD conversion and signal amplification, is output to the signal processing circuit 220. In another embodiment, the solid-state image sensor 108 is not limited to a CMOS image sensor but may be a CCD image sensor.

  The driver signal processing circuit 112 accesses the memory 114 and reads unique information of the electronic scope 100. The unique information of the electronic scope 100 includes, for example, the number of pixels and sensitivity of the solid-state image sensor 108, a compatible rate, a model number, and the like. The driver signal processing circuit 112 outputs the unique information read from the memory 114 to the system controller 202.

  The system controller 202 performs various calculations based on the unique information of the electronic scope 100 and generates a control signal. The system controller 202 uses the generated control signal to control the operation and timing of various circuits in the processor 200 so that processing suitable for an electronic scope connected to the processor 200 is performed. The system controller 202 may be configured to have a table in which a model number of the electronic scope is associated with control information suitable for the electronic scope of this model number. In this case, the system controller 202 refers to the control information in the correspondence table and controls the operation and timing of various circuits in the processor 200 so that processing suitable for the electronic scope connected to the processor 200 is performed.

  The timing controller 204 supplies clock pulses to the driver signal processing circuit 112 in accordance with timing control by the system controller 202. The driver signal processing circuit 112 drives and controls the solid-state imaging device 108 at a timing synchronized with the frame rate of the video processed on the processor 200 side in accordance with the clock pulse supplied from the timing controller 204.

  The signal processing circuit 220 stores digital image data output from the driver signal processing circuit 112 in the image memory 222. Further, the signal processing circuit 220 reads the image data stored in the image memory 222 at a predetermined timing (that is, corresponding to the horizontal and vertical synchronization frequencies of the monitor 300), and performs predetermined image processing (for example, on the read image data). The image data after the image processing is performed is converted into a video signal of a predetermined format (for example, NTSC format) and output to the monitor 300. As a result, an endoscopic image of the subject imaged by the solid-state image sensor 108 of the electronic endoscope 100 is displayed on the monitor 300. Each operation of the signal processing circuit 220 described above is performed under the control of the timing controller 204 and the system controller 202.

  A distance measuring sensor 310 is disposed around the monitor 300 (for example, on the upper side). The distance measuring sensor 310 is a sensor that measures the distance between the monitor surface of the monitor 300 and the observer (operator), and is controlled by the system controller 202. The distance measuring sensor 310 is, for example, a sensor that combines a heat ray sensor that is a human sensor and an ultrasonic sensor that measures a distance, and detects whether or not there is a person in front of the distance measuring sensor 310, If it is detected, the distance between the monitor surface of the monitor 300 and the operator is measured, and the result is transmitted to the system controller 202 (described later).

  Next, automatic enhancement processing executed by the electronic endoscope apparatus 1 of the present embodiment will be described. FIG. 2 is a diagram for explaining human visual characteristics, which are prerequisites for explaining the enhancement processing executed in the electronic endoscope apparatus 1 of the present embodiment.

Now, the distance between the monitor 300 and the observer (operator) is set to x1 (for example, 50 cm), which is the reference for the observation distance. When the size of a certain image displayed on the monitor 300 at this time is y1, the observer observes the image at the following viewing angle θ.
θ = atan (y1 / x1) (1)

Next, consider a case where the observation distance is changed from x1 to x2 (x2 = α × x1). At the observation distance x2, the size y2 of the image on the monitor 300 that can be observed at the same viewing angle θ as that at the observation distance x1 is as follows, similarly to the equation (2).
θ = atan (y2 / x2) (2)

Then, the following equation (3) is obtained from the equations (1) and (2).

When the monitor 300 is observed at different distances x1 and x2 at the same viewing angle with respect to the image on the monitor 300, if x2 = α × x1, the following equation (4) is derived.
y2 = α × y1 (4)

  Expression (4) means that when the image on the monitor 300 is observed from a position separated by α times, the size of the image that can be observed becomes 1 / α times.

  Next, consider the relationship between the spatial frequency of the image to be observed and the resolution. FIG. 3 is a diagram for explaining enhancement processing executed in the electronic endoscope apparatus 1 of the present embodiment. FIG. 3 shows the relationship between the spatial frequency (horizontal axis) and the resolving power (vertical axis) of the image to be observed. The dotted line represents the characteristics when the enhancement processing is not performed, and the solid line represents the enhancement processing. This shows the characteristics when.

  As shown by the dotted line in FIG. 3, in general, when enhancement processing is not performed, an image having a lower spatial frequency (that is, a coarse elephant) has a higher resolution, and an image having a higher spatial frequency (that is, a fine image) has a higher resolution. Lower.

  The enhancement processing is processing for increasing the resolving power of a predetermined spatial frequency F, and as shown by a solid line in FIG. 3, the predetermined frequency F (hereinafter referred to as “enhancement frequency F”) is used as a peak to increase the resolving power overall. Enhance processing is performed. By adjusting the enhancement frequency F, the balance of the emphasized spatial frequency can be changed, and the predetermined spatial frequency of the observation image can be further enhanced, so that a desired observation image can be obtained.

Here, when the maximum spatial frequency that can be resolved by the monitor 300 is the maximum spatial frequency Fn (for example, 1280 TV lines), the enhancement frequency F is expressed as follows using a constant β (0 <β <1): Can express.
F = β × Fn (5)

  As described above, since the size of the image on the monitor 300 varies depending on the observation position, the spatial frequency of the image varies depending on the observation position. That is, when the image on the monitor 300 is observed close to the monitor 300, the spatial frequency of the image is low, and when the image is observed away, the spatial frequency of the image is high. The enhancement processing of the present embodiment pays attention to the point that the spatial frequency of the image depends on the observation distance, and is configured to automatically adjust the optimum enhancement frequency F according to the observation distance. Hereinafter, the automatic enhancement process of this embodiment will be described in detail.

The horizontal size of the monitor 300 is Y, the maximum horizontal spatial frequency is Fn, the optimum enhancement frequency at the observation distance x1 is F1, and the period (size) of the image on the monitor corresponding to the spatial frequency F1 is y1. Then, the following relationship is obtained.
y1 = Y / F1 (6)

Then, the following equation (7) is obtained from the equations (5) and (6).

及び以下の式（９）を得る。

Next, consider the case of observation at a distance x2 (x2 = α × x1) different from x1. Assuming that the optimum enhancement frequency at the observation distance x2 is F2 and the period (size) of the image on the monitor corresponding to the spatial frequency F2 is y2, the following equation (8) is obtained from the equations (4) and (7). )

And the following equation (9) is obtained.

  In the equations (8) and (9), the horizontal size Y of the monitor 300 and the maximum spatial frequency Fn in the horizontal direction are constants determined by the specifications of the monitor 300, so that the optimum enhancement frequency at the observation distance x2 is determined. It can be seen that the period (magnitude) y2 of the image on the monitor corresponding to F2 and the spatial frequency F2 is obtained by obtaining constants α and β.

  In the present embodiment, as for the constant β, the optimum enhancement frequency F1 at the observation distance x1 is obtained by a subjective evaluation experiment. Specifically, at an observation distance x1, a predetermined image on the monitor is observed while changing the enhancement frequency F, the enhancement frequency F when the sharpest feeling is obtained is obtained, and the enhancement frequency F and the monitor 300 are A constant β (for example, 0.3) is obtained by substituting the maximum resolvable spatial frequency Fn into the equation (5). The parameters of the observation distance x1, the optimum enhancement frequency F1 at the observation distance x1, and the maximum spatial frequency Fn that can be resolved by the monitor 300 are input by the user via the front panel 218 and stored in a memory (not shown). The constant β is calculated using each parameter by the system controller 202, and is stored in a memory (not shown) like each parameter.

  In the present embodiment, the constant α is obtained by obtaining the distance between the observer and the monitor 300 (that is, the observation distance x2) by the distance measuring sensor 310. Specifically, as will be described later, the system controller 202 obtains a constant α (= x2 / x1) from the observation distance x2 detected by the distance measuring sensor 310 and the known observation distance x1.

  In this embodiment, the optimum constants α and β and the maximum spatial frequency Fn that can be resolved by the known monitor 300 are substituted into the equation (9) to obtain the optimum enhancement frequency at the observation distance x2. F2 is obtained and optimum enhancement processing is automatically performed.

  Hereinafter, the automatic enhancement process performed by the electronic endoscope apparatus 1 of the present embodiment will be described. FIG. 4 is a flowchart of the automatic enhancement process executed by the system controller of the present embodiment. FIG. 5 is a block diagram illustrating the configuration of the distance measuring sensor according to the present embodiment. FIG. 6 is a flowchart of a distance measurement routine executed in the automatic enhancement process of FIG. This process is executed when an automatic enhancement process is instructed by operating the front panel 218.

  When this routine is started, step S101 is executed. In step S101, the distance measurement subroutine is called, and the distance sensor 310 determines the distance between the observer and the monitor 300 (that is, the observation distance x2).

  As shown in FIG. 5, the distance measuring sensor 310 includes a sensor S <b> 1 that detects a person located on the left side of the monitor 300, a sensor S <b> 2 that detects a person located in front of the monitor 300, and the monitor 300. And a sensor S3 for detecting a person located on the right side. As described above, each of the sensors S1, S2, and S3 includes a heat ray sensor and an ultrasonic sensor, and whether or not a person exists within a predetermined detection angle, and when a person exists, It is possible to measure the distance between the sensors.

  When the distance measurement subroutine is called, step S201 is executed. In step S201, it is determined whether the heat ray sensor of sensor S1 has detected a person. When the heat ray sensor of the sensor S1 detects a person (S201: YES), the process proceeds to S202. On the other hand, when the heat ray sensor of the sensor S1 does not detect a person in step S201 (S201: NO), the process proceeds to S203.

  In step S202, the distance D1 with the person detected in step S201 is measured by the ultrasonic sensor of sensor S1, and stored in a memory (not shown). Next, the process proceeds to step S203.

  In step S203, it is determined whether the heat ray sensor of sensor S2 has detected a person. When the heat ray sensor of sensor S2 detects a person (S203: YES), the process proceeds to S204. On the other hand, in step S203, when the heat ray sensor of sensor S2 does not detect a person (S203: NO), the process proceeds to S205.

  In step S204, the distance D2 to the person detected in step S203 is measured by the ultrasonic sensor of sensor S2, and stored in a memory (not shown). Next, the process proceeds to step S205.

In step S205, it is determined whether or not the heat ray sensor of sensor S3 has detected a person. When the heat ray sensor of the sensor S3 detects a person (S205: YES), the process proceeds to S206. On the other hand, in step S205, when the heat ray sensor of sensor S3 does not detect a person (S205: NO), the process proceeds to S207.

  In step S206, the distance D3 to the person detected in step S205 is measured by the ultrasonic sensor of sensor S3 and stored in a memory (not shown). Next, the process proceeds to step S207.

  In step S207, the information (data) of the distances D1, D2, and D3 measured in steps S202, S204, and S206 and stored in the memory is transferred to the system controller 202, and this subroutine is terminated.

  When the distance measurement subroutine ends, the process proceeds to S102 (FIG. 4). Step S102 is an enhancement frequency calculation step for obtaining the optimum enhancement frequency F2 at the observation distance x2. In this step, the system controller 202 obtains the minimum values of the distances D1, D2, and D3 obtained by the distance measurement subroutine, and calculates the minimum value as the distance to the observer (that is, the observation distance x2). Specifically, a constant α (= x2 / x1) is obtained from the observation distance x2 and the known observation distance x1, and this, the known constant β, and the maximum spatial frequency Fn that can be resolved by the monitor 300 are expressed by Equation (9). To obtain the optimum enhancement frequency F2 at the observation distance x2. Next, the process proceeds to step S103.

  In step S103, enhancement processing centered on the enhancement frequency F2 obtained in S102 is performed. That is, the system controller 202 controls the signal processing circuit 220 and performs enhancement processing on the image data input from the driver signal processing circuit 112 so that the enhancement frequency F2 has a peak. The enhanced image data is converted into a video signal by the signal processing circuit 220 and output to the monitor 300. Next, the process proceeds to step S104.

  In step S104, it is determined whether or not an instruction to end automatic enhancement processing is input by operating the front panel 218 (whether or not the switch SW is turned off). When an instruction to end automatic enhancement processing is input (S104: YES), the automatic enhancement processing ends. On the other hand, when the end instruction of the automatic enhancement process is not input (S104: NO), the process returns to S102.

  By executing the loop of steps S102 to S104, the distance between the observer and the monitor 300 is sequentially measured, and automatic enhancement processing corresponding to the distance is executed.

  Therefore, according to the automatic enhancement processing of the present embodiment, the optimum enhancement processing is performed according to the distance between the monitor 300 and the surgeon, and the surgeon always looks at the image that has been subjected to the optimum enhancement processing. The endoscope can be operated. Further, since the operator does not need to perform another operation while operating the endoscope, the operator can concentrate on the operation of the endoscope, and as a result, the diagnosis time is shortened.

1 Electronic Endoscope 100 Electronic Endoscope 200 Electronic Endoscope Processor 202 System Controller 220 Signal Processing Circuit 300 Monitor 310 Distance Sensor

Claims (5)

An electronic endoscope comprising: an electronic endoscope that outputs an endoscopic image as a video signal; a monitor; and a processor for electronic endoscope that processes the video signal and generates a video signal that can be displayed on the monitor. An endoscopic device,
A distance measuring means for measuring a distance between the monitor and an observer located in front of the monitor;
The electronic endoscope processor includes a signal processing circuit that generates an image from the video signal and performs enhancement processing around a predetermined spatial frequency of the image,
The electronic endoscope apparatus, wherein the signal processing circuit changes the predetermined spatial frequency based on a distance measured by the distance measuring unit.   The signal processing circuit has a reference spatial frequency determined so that an optimal enhancement process is performed when a distance between the monitor and the observer is a predetermined reference distance, and a maximum spatial frequency that can be resolved by the monitor, The electronic endoscope apparatus according to claim 1, wherein the predetermined spatial frequency is changed based on a distance measured by the distance measuring unit. The distance measuring means includes a plurality of sensor units,
Each of the plurality of sensor units includes a human sensor that detects whether or not the observer is present, and a distance measuring sensor that measures a distance between the monitor and the observer. The electronic endoscope apparatus according to claim 1 or 2.   4. The signal processing circuit changes the predetermined spatial frequency based on a minimum distance among distances between the monitor and the observer measured by the plurality of sensor units. The electronic endoscope apparatus described in 1. The electronic endoscope apparatus according to claim 3, wherein the human sensor is a heat ray sensor, and the distance measuring sensor is an ultrasonic sensor.

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