JP2019162165A - Endoscope system - Google Patents

Abstract

To provide an endoscope and an endoscope system which can suppress halation or loss of shadow detail without increasing the number of illumination parts.SOLUTION: The endoscope system comprises: an endoscope having an imaging part; a light source device supplying irradiation light for irradiating an analyte; a luminance calculation part calculating luminance of an image of the analyte acquired by the imaging part; and a control part controlling the light source device. The imaging part performs imaging by a rolling shutter method for sequentially exposing a plurality of blocks at different timings. The luminance calculation part calculates luminance of an image in a first region, and luminance of an image in a second region in which a block is different from that of the first region. The control part compares the luminance in the first region with the luminance in the second region, then, based on the comparison result, changes a first light emission quantity which is a light emission quantity of the light source device when exposing the first region, in comparison with the second light emission quantity which is a light emission quantity of the light source device when exposing the second region.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an endoscope system.

  In the field of endoscopes, an imaging device is mounted at the tip of an insertion portion that is inserted into the body of a subject, and an image captured by the imaging device is displayed on a display to show the state of the body of the subject. Electronic endoscope systems for observation are widely known.

  However, when imaging a subject (stomach, large intestine, nasal cavity, etc.) to be observed with an electronic endoscope system, it is difficult to uniformly illuminate the entire illumination range. Includes a bright part and a dark part, and so-called white-out or black-out tends to occur. Various techniques have been proposed to suppress such whiteout and blackout. For example, Patent Document 1 includes a plurality of illumination units in which the illumination areas partially overlap and the peak positions of the light distributions are shifted from each other, and by adjusting the light projection intensity of the plurality of illumination units, To improve the natural image quality.

  However, in the technique of Patent Document 1, in order to perform uniform illumination, it is necessary to provide a plurality of illumination units (light distribution lenses) in the insertion unit of the endoscope. For example, a forceps hole, an air supply port, a water supply port, and the like are disposed in the insertion portion, and an imaging element and an objective lens must also be disposed at the distal end of the insertion portion. The thickness is limited, and increasing the number of light sources and light guides for uniform illumination causes an increase in the diameter of the insertion portion, which is not preferable. As described above, it is difficult for the conventional technology to improve whiteout and blackout while maintaining the diameter of the insertion portion.

JP 2014-230708 A

  An object of the present invention is to provide an endoscope and an endoscope system that can suppress whiteout and blackout in an image without increasing the number of illumination units.

  In order to solve the above problems, an endoscope system according to a first aspect of the present invention includes an endoscope having an imaging unit, and a light source that supplies irradiation light for irradiating the subject to the endoscope. An apparatus, a luminance calculation unit that calculates the luminance of the image of the subject obtained from the imaging unit, and a control unit that controls the light source device. The imaging unit is configured to perform imaging by a rolling shutter system that sequentially exposes a plurality of blocks at different timings. The luminance calculation unit calculates the luminance in the first region of the image and the luminance in the second region having a block different from the first region of the image. The control unit compares the luminance in the first region with the luminance in the second region, and based on the comparison result, determines the first emitted light amount that is the emitted light amount of the light source device when exposing the first region. In comparison with the second light emission amount that is the light emission amount of the light source device when the two areas are exposed.

Here, the first area can be located closer to the center of the image than the second area.
Further, the control unit may be configured to perform control such that the second light emission amount is decreased when the first light emission amount is increased, and the second light emission amount is increased when the first light emission amount is decreased. it can. Further, the control unit can perform control to change the first light emission amount so that the sum of the first light emission amount and the second light emission amount is substantially the same before and after the change of the first light emission amount.

  The control unit can be configured to compare a luminance average value, which is an average value of luminance in the entire image, with a target value, and to control an exposure time in the imaging unit based on the comparison result. Further, the control unit can change the timing for starting the period for setting the first light emission amount in accordance with the change in the exposure period for exposing the subject.

  The light source device maintains a first light emission amount at a second value during a first period in which the light emission amount is continuously increased from a first value to a second value during a period in which the first region is exposed. The amount of emitted light can be changed so as to have a second period of time and a third period of continuously decreasing the amount of emitted light from the second value to the third value. By performing such control, a more natural image can be obtained. Note that the first period and the third period can be set to have a length for performing exposure of a plurality of scanning lines.

  The light source device includes a plurality of light emitting units, and the control unit includes a luminance in a third area illuminated by one first light emitting unit among the plurality of light emitting units, and a first of the plurality of light emitting units. The luminance in the fourth region illuminated by the second light emitting unit different from the first light emitting unit is compared, and according to the comparison result, the light emitting amount of the first light emitting unit and the light emitting amount of the second light emitting unit are Can be configured to control. In this case, the plurality of light emitting units can be arranged along the direction of the scanning line of the imaging unit.

  According to the present invention, it is possible to provide an endoscope and an endoscope system that can suppress overexposure and blackout in an image without increasing the number of illumination units.

It is the schematic explaining the schematic structure of the endoscope system of 1st Embodiment. FIG. 2 is a block diagram illustrating an internal structure of a processor 200 and a light source device 300 in FIG. 1. It is the schematic explaining the operation | movement of the light source device 300 of 1st Embodiment. It is a timing chart explaining operation | movement of the light source device 300 of 1st Embodiment. It is a timing chart explaining operation | movement of the light source device 300 of 1st Embodiment. It is a flowchart explaining operation | movement of the endoscope system 1 of 1st Embodiment. It is a block diagram explaining the structure of the endoscope system 1 which concerns on 2nd Embodiment. It is a block diagram explaining the structure of the endoscope system 1 which concerns on 3rd Embodiment. It is a timing chart explaining operation | movement of the light source device 300 of 3rd Embodiment. It is a flowchart explaining operation | movement of the endoscope system 1 of 3rd Embodiment. It is a flowchart explaining operation | movement of the endoscope system 1 of 3rd Embodiment.

  Hereinafter, the present embodiment will be described with reference to the accompanying drawings. In the accompanying drawings, functionally identical elements may be denoted by the same numbers. Note that the attached drawings show an embodiment and an implementation example according to the principle of the present disclosure, but these are for understanding the present disclosure and are never used to interpret the present disclosure in a limited manner. is not. The descriptions in this specification are merely exemplary, and are not intended to limit the scope of the claims or the application in any way whatsoever.

  This embodiment has been described in sufficient detail for those skilled in the art to implement the present disclosure, but other implementations and forms are possible, without departing from the scope and spirit of the technical idea of the present disclosure. It is necessary to understand that the configuration and structure can be changed and various elements can be replaced. Therefore, the following description should not be interpreted as being limited to this.

[First Embodiment]
First, the endoscope system according to the first embodiment of the present invention will be described in detail. FIG. 1 is an external perspective view of the endoscope system 1 according to the first embodiment, and FIG. 2 is a block configuration diagram showing a more detailed configuration of the endoscope system 1. The endoscope system 1 generally includes an endoscope 100, a processor 200, a light source device 300, a display 400, and an input unit 500. The endoscope 100 is configured to be insertable into the body of a subject and has a function of capturing an image of a subject and transmitting an image signal of the captured image to the processor 200. The processor 200 receives the image signal from the endoscope 100 and executes predetermined signal processing.

  The light source device 300 is configured to be connectable to the processor 200, and includes a light source that emits irradiation light for irradiating a subject. The light source device 300 may be configured separately from the processor 200 and configured to be connectable to the processor 200, or may be incorporated in the processor 200.

The endoscope 100 includes an insertion portion 101, a hand operation portion 102, a bending portion 103, a distal end portion 104, a universal cable 105, and a connector portion 106.
As shown in FIG. 1, the endoscope 100 is flexible and includes an insertion portion 101 for insertion into the body of a subject. The insertion unit 101 is connected to the hand operation unit 102 at one end thereof. The hand operation unit 102 includes, for example, a bending operation knob 102 </ b> A and other operation units that can be operated by a user, and is a part for allowing an operator to perform various operations for imaging by the endoscope system 1.

  A bending portion 103 configured to be bendable is provided at the distal end of the insertion portion 101. The bending portion 103 is bent by pulling of an operation wire (not shown) interlocked with the rotation operation of the bending operation knob 102A provided in the hand operation portion 102. Further, a distal end portion 104 having an imaging element (imaging portion) is connected to the distal end of the bent portion 103. By changing the direction of the distal end portion 104 in accordance with the bending operation of the bending portion 103 caused by the rotation operation of the bending operation knob, the imaging region by the endoscope 100 can be changed. A universal cable 105 extends from the opposite side of the hand operation unit 102 toward the connector unit 106. The universal cable 105 includes a light guide, various wirings, and the like. The connector unit 106 includes various connectors for connecting the endoscope 100 to the processor 200.

The internal structures of the endoscope 100, the processor 200, and the light source device 300 will be described in detail with reference to the block diagram of FIG. A light guide 111 extends from the distal end portion 104 to the connector portion 106 inside the endoscope 100. A condensing lens 112 is provided on the distal end side of the light guide 111, and the light emitted from the light guide 111 is condensed by the condensing lens 112 and irradiated toward the subject.
The endoscope 100 includes an objective lens 113 and an image sensor 114 at the distal end portion 104. The objective lens 113 collects scattered light and reflected light from the subject and forms an image of the subject on the light receiving surface of the image sensor 114.

  The image sensor 114 can be configured by a CMOS sensor (Complimentary Metal Oxide Semiconductor Sensor) as an example. When the image sensor 114 is a CMOS sensor, the CMOS sensor converts an image of the subject into an image signal by a rolling shutter method, for example, and outputs the image signal. In the rolling shutter system, for example, exposure is sequentially performed with one block including one pixel line (scanning line) or a plurality of pixel lines as a unit, and image information is acquired for each block. The timing of exposure differs between a plurality of blocks (a plurality of pixel lines) in one frame. In the following description, it is assumed that one block is one pixel line.

  The pixels in one pixel line are exposed simultaneously to acquire an image, but the plurality of pixel lines are exposed with a slight time difference. In this embodiment, the light source device 300 performs illumination control, which will be described later, corresponding to the rolling shutter method, thereby suppressing the occurrence of the above-described overexposure or blackout.

  The image sensor 114 is controlled by signals (a gain control signal, an exposure control signal, a shutter speed control signal, etc.) supplied from the signal processing circuit 116, and outputs an image signal of a captured image to the signal processing circuit 116. The signal is supplied via the A / D conversion circuit 115.

  Next, the internal structures of the processor 200 and the light source device 300 will be described with reference to FIG. The processor 200 includes a CPU 201, a luminance calculation unit 202, an image processing circuit 203, and an interface (I / F) 204.

  The CPU 201 controls the endoscope 100, the processor 200, and the light source device 300 according to a control program stored in a memory (not shown). The CPU 201 is configured to be able to receive an input signal from the input unit 500 via the interface 204. The CPU 201 also outputs a control signal according to this input signal to the endoscope 100 or the light source device 300.

  The luminance calculation unit 202 has a function of calculating the luminance of the subject image obtained by the image sensor 114. Specifically, as an example, the luminance calculation unit 202 includes a screen luminance average value Bave that is an average of the luminance of the entire image (all pixels) of one frame and a screen central portion (hereinafter simply referred to as a central portion) of the image of one frame. A central luminance average value Bcnt, which is the average of the luminance in the vicinity, and a peripheral luminance average value Bedg, which is the average luminance of the peripheral portion in the vertical direction of the image of one frame (hereinafter simply referred to as the peripheral portion). Can be configured to. That is, the luminance calculation unit 202 calculates not only the average value of the entire luminance of the captured image but also the average value of the luminance of a part of the captured image, thereby calculating the difference in brightness in one image. calculate.

  The CPU 201 functions as a control unit that controls the amount of emitted light in the light source device 300 based on the calculated values Bave, Bcnt, and Bedg. That is, in the first embodiment, the overall luminance of the image and the luminance of a part (for example, the central portion and the peripheral portion) are calculated together, and the illumination light control based on this is performed in the CPU 201. A natural image in which overexposure and blackout are suppressed can be obtained.

  Note that the “central part” and “peripheral part” here do not have to be strictly the center or the peripheral position in the screen, and as a relative positional relationship, the central part is closer to the screen than the peripheral part. As long as it is close to the center. In the above example, the average value of the luminance is calculated, but this is merely an example of a scale for determining the luminance, and the luminance may be determined based on other values. The median value, maximum value, and standard deviation of luminance may be calculated, or these multiple types of values may be calculated simultaneously.

  Further, the luminance calculation unit 202 detects the rising and falling edges of the vertical synchronization signal Vsync received from the image sensor 114 via the signal processing circuit 116, detects the start and / or end of one frame, and detects the detection signal. Tvsync is output. The screen luminance average value Bave, the central luminance average value Bcnt, and the peripheral luminance average value Bedg can be calculated in the range of the one frame according to the start and end of the detected one frame. However, the determination of the average value of luminance and the like is not limited to the one-frame image, and can be calculated for a plurality of frames.

  The image processing circuit 203 performs predetermined image processing on the image signal output from the signal processing circuit 116 and outputs the image signal to the display 400.

  As an example, the light source device 300 includes a pulse width modulation device 301, an LED 302 as a light source, and a condenser lens 303. The pulse width modulation device 301 (PWM) modulates the pulse width of the output signal in accordance with a control signal from the CPU 201. The LED 302 is configured to emit light having a light amount according to the duty ratio of the received pulse width modulation signal. The condensing lens 303 is configured to condense the output light from the LED 302 onto the incident end face of the light guide 111. As will be described in detail below, the light source device 300 temporally changes the amount of light emitted from the LED 302 in accordance with the luminance calculated by the luminance calculation unit 202, thereby suppressing the above-described whiteout and blackout. ing.

Next, the operation of the light source device 300 according to the first embodiment will be described with reference to FIGS.
First, the operation of the conventional light source device 300 will be described with reference to FIG.
When the image sensor 114 is composed of a CMOS sensor that employs a rolling shutter system as described above, exposure at each pixel line is executed at a timing according to the vertical synchronization signal Vsync. Prior to the start of exposure to each pixel line, discharge of electric charge is performed in each pixel in the pixel line, and then exposure to each pixel line and readout of signals are started. The exposure time Te for each pixel line in one frame is set to, for example, 1/60 seconds or less when the frame rate is 30 fps (1/30 seconds). However, the start timing of exposure of a plurality of pixel lines is slightly shifted.

  Here, as shown in FIG. 3, when the light emission amount L of the light source device 300 is constant regardless of the passage of time, a plurality of pixel lines in one frame are also exposed with the same exposure amount. In such a light emission amount (exposure amount), for example, when imaging a tubular subject (esophagus, duodenum, large intestine, etc.) with the longitudinal direction as the depth direction, as shown by reference numeral P1 in FIG. While the illumination light does not reach the subject and becomes a dark image, the illumination light tends to hit the wall surface of the subject and become a bright image at the periphery of the screen. In such an image, black crushing tends to occur in a dark part (near the center), while whiteout tends to occur in a bright part (peripheral part).

  Further, for example, when imaging a subject's wall surface (for example, stomach wall) from the front, illumination light is reflected and scattered on the stomach wall near the center of the screen as shown by reference numeral P2 in FIG. On the other hand, the illumination light does not hit the stomach wall at the periphery of the screen and tends to be an extremely dark image. Also in this case, whitening occurs in a bright image (near the center), and black collapse tends to occur in a dark image (peripheral portion), resulting in an unnatural image that is difficult to see as a whole.

  FIG. 4 shows the operation of the light source device 300 according to the first embodiment. In the first embodiment, in the exposure of a plurality of pixel lines within one frame, a period for exposing pixel lines corresponding to the peripheral part of the screen, and a period for exposing pixel lines corresponding to the central part of the screen, Thus, control is performed so that the light emission amount of the light source device 300 is different.

  For example, when imaging a tubular subject (such as the large intestine) as in “Case 1” of FIG. 4, the light emission amount Lcnt ( The light emission amount Lcnt at the center exposure is set to be larger than the light emission amount Ledg (the light emission amount Ledg at the peripheral exposure) of the light source device 300 in the period T1 in which the peripheral portion of the screen is exposed. Thereby, the pixel line near the center of the screen is illuminated brightly with a larger amount of light, and black crushing is suppressed. On the other hand, since the vicinity of the periphery of the screen is illuminated darker with a smaller amount of light than the center, whiteout is suppressed. The period T1 can be set to a period between the periods T2 set to be skipped. Note that, as described above, when the light emission amounts Lcnt and Ledg are increased or decreased, it is preferable that the average value of both the light amounts is kept constant. This point will be described later.

  On the other hand, when a wall-like subject such as a stomach wall is illuminated from the front as shown in “Case 2” in FIG. 4, a period T2 in which the vicinity of the center of the screen of one frame is exposed, contrary to Case 1. The light emission amount Lcnt ′ of the light source device 300 is made smaller than the light emission amount Ledg ′ of the light source device 300 in the period T1 during which the peripheral portion of the screen is exposed. Thereby, the vicinity of the periphery of the screen is irradiated with a larger amount of light, and black crushing is suppressed. On the other hand, since the vicinity of the center of the image is illuminated darker with a smaller amount of light than the periphery, whiteout is suppressed.

  In both cases of Case 1 and Case 2, when changing the amount of emitted light of the light source device 300, the amount of emitted light does not change abruptly (in a stepped manner), but changes continuously. Control. For example, in Case 1, the period T2 is further divided into a light quantity increase period T21, a light quantity maintenance period T22, and a light quantity decrease period T23. The light quantity increase period T21 is a period in which the light emission quantity of the light source device 300 is increased from the value in the immediately preceding period T1 to the light quantity Lcnt. The light quantity maintenance period T22 is a period during which the above light quantity Lcnt is maintained. Further, the light amount reduction period T23 is a period in which the light emission amount of the light source device 300 is decreased from the light amount Lcnt toward the value in the period T1.

  The lengths of the light quantity increase period T21 and the light quantity decrease period T23 are set to a period in which, for example, about 10 to 100 pixel lines are exposed. In this way, by setting the light amount increase period T21 and the light amount decrease period T23 so that the exposure amount of a plurality of adjacent pixel lines gradually increases or decreases, the brightness of the image in the vertical direction in one image is increased. It is possible to prevent sudden changes and unnatural images.

  Similarly, in Case 2, the period T1 is further divided into a light quantity increase period T11, a light quantity maintenance period T12, and a light quantity decrease period T13. The light amount increase period T11 is a period in which the light emission amount of the light source device 300 is increased from the value in the immediately preceding period T2 to the light amount Ledg '. The light quantity maintenance period T12 is a period during which the above-described light quantity Ledg 'is maintained. Further, the light amount decrease period T13 is a period in which the light emission amount of the light source device 300 is decreased from the light amount Ledg 'toward the value in the period T2.

  Whether the central part of the screen is darker than the peripheral part as in Case 1 or whether the central part of the screen is brighter than the peripheral part as in Case 2, the central luminance average value Bcnt calculated by the luminance calculating unit 202 , And the peripheral luminance average value Bedg. The magnitudes of the light amounts Lcnt, Lcnt ′, Ledg, and Ledg ′ can also be set according to the central luminance average value Bcnt and the peripheral luminance average value Bedg.

  FIG. 5 shows a change in the amount of light emitted from the light source device 300 when a high-speed shutter having a short exposure time Te of the electronic shutter is employed. When the exposure time Te is short, the exposure time Tf for one frame is also shorter than in the case of FIG. 4, so the start timing of the period T2 during which the pixel line corresponding to the center of the screen is exposed is also the same as in FIG. The timing is set relatively late. The CPU 201 changes the start timing of the period T2 according to the determined exposure time Te.

  Next, a control procedure of the light source device 300 in the endoscope system according to the first embodiment will be described with reference to the flowchart of FIG. First, at least one frame is imaged in a state where the light emission amount L, the exposure time Te, and the like of the light source device 300 are set to initial values. When the luminance calculation unit 202 detects that the imaging of one frame image has been completed (step S11), the average luminance value (screen luminance average value Bave) of all the pixels in the captured one frame image is obtained. Calculated by the luminance calculation unit 202. Then, the CPU 201 determines whether or not the screen luminance average value Bave is larger than the target luminance Baveget (step S12).

  When the target luminance Bavegt is equal to or higher than the screen luminance average value Bave (YES), the exposure amount in one frame is increased (step S13), while when the target luminance Bavegt is smaller than the screen luminance average value Bave (NO). The exposure amount in one frame is reduced (step S14).

  Then, the CPU 201 sets a sensor gain (analog gain / digital gain) in the image sensor 114 according to the exposure amount, and outputs a control signal for instructing the sensor gain to the image sensor 114 (step). S15).

Further, according to the exposure amount of one frame determined in step S13 or S14, the exposure time Te per pixel line and the exposure start timing (charge discharge pulse generation timing) are set (step S16).
Further, according to the exposure amount of one frame determined in step S13 or S14, the average light emission level Lave of the light source device 300 in the exposure of one frame is set (step S17).

  Subsequently, the magnitude relationship between the central luminance average value Bcnt calculated by the luminance calculation unit 202 and the peripheral luminance average value Bedg is determined (step S18). When Bcnt is extremely large compared to Bedg (for example, 100 times or more), or when Bcnt is extremely small compared to Bedg (for example, 1/100 or less), when exposing the central portion of the screen The light emission amount Lcnt of the light source device 300 is increased or decreased (step S19). Conversely, if the ratio between Bcnt and Bedg is within a predetermined range, the amount of emitted light Lcnt is not changed (step S20). The increase or decrease amount ΔL of the emitted light amount Lcnt is set based on the difference between Bcnt and Bedg.

  When the light emission amount Lcnt of the light source device 300 when exposing the central portion of the screen is thus determined, the light source when exposing the peripheral portion of the screen is obtained by subtracting the light emission amount Lcnt from twice the average light emission amount Lave. The amount of emitted light Ledg of the apparatus 300 is calculated (step S21). Specifically, Ledg is calculated as Ledg = 2 × Lave−Lcnt (Formula 1). In other words, the emitted light amount Lcnt is changed so that the sum of the emitted light amount Lcnt and the emitted light amount Ledg is substantially the same before and after the change of the emitted light amount. Note that the sum of the light emission amount Lcnt and the light emission amount Ledg does not always have to be the same, and it is possible to give a certain range of change from the average light emission amount Lave.

  In this embodiment, that is, if the light emission amount Lcnt of the light source device 300 when exposing the central portion of the screen increases, the light emission amount Ledg of the light source device 300 when exposing the peripheral portion of the screen decreases and vice versa. If the amount of emitted light Lcnt decreases, the amount of emitted light Ledg increases. By setting the light emission amounts Lcnt and Ledg according to Equation 1, even if the light emission amounts Lcnt and Ledg change, the average luminance of the entire screen can be kept constant.

  Imaging in the next frame is performed by the light emission amounts Lcnt and Ledg set in this way. The set light emission amounts Lcnt, Ledg, and Lave are temporarily stored in a memory (not shown), but the light emission amounts Lcnt, Ledg, and Lave are newly set at a predetermined timing, and the stored value of the memory is reset each time. (Step S22).

  In the flowchart of FIG. 6, an example has been described in which values Bave, Bcnt, Bedg, etc. relating to screen brightness are calculated for each frame, and the amount of emitted light is corrected for each frame. For example, the measurement of the value relating to the luminance may be performed once every plural frames.

  As described above, according to the endoscope system of the first embodiment, when the imaging device 114 performs imaging by the rolling shutter method, the luminance calculation unit 202 performs luminance in the central portion of the screen. Bcnt and the luminance Bedg at the periphery of the screen are calculated, and based on the comparison result, the light emission amount of the light source device 300 when exposing the central portion of the screen and the light emission of the light source device 300 when exposing the peripheral portion of the screen Change in comparison with light quantity. Thereby, even when a bright portion and a dark portion are mixed in one screen, it is possible to prevent overexposure and blackout. The above operation is sufficient if the light source device 300 has a single light source. For this reason, according to the first embodiment, it is possible to suppress overexposure or blackout in the screen without increasing the number of illumination units.

  The operation of the first embodiment (the operation of FIG. 6) is executed only when the screen luminance average value Bave is equal to or higher than the lower limit value, and when it is less than the lower limit value, the operation of FIG. It is also possible to make the amount of emitted light uniform over the entire screen. For example, when the image is so dark that the exposure time Te per pixel line must be significantly longer than 1/60 seconds, the exposure periods overlap between adjacent frames, and the first The advantage of the embodiment (FIG. 6) may not be obtained. Therefore, in such a case, it is possible to configure the imaging so that the light emission amount of the light source device 300 is always uniform.

[Second Embodiment]
Next, an endoscope system 1 according to a second embodiment will be described with reference to FIG. The endoscope system 1 according to the second embodiment is substantially composed of an endoscope 100, a processor 200, a light source device 300, a display 400, and an input unit 500, as compared with the first embodiment. Are the same. However, in the second embodiment, the CPU 201 </ b> A and the luminance calculation unit 202 </ b> A are provided inside the endoscope 100. The CPU 201A and the luminance calculation unit 202A correspond to the CPU 201 and the luminance calculation unit 202 of the first embodiment.

  The light source device 300 is also built in the endoscope 100. As an example, the light source device 300 according to the second embodiment includes a pulse width modulation device 301A, an LED 302A, and a condensing lens 303A inside the endoscope 100. This is the same as the pulse width modulation device 301, the LED 302 as the light source, and the condenser lens 303 of the embodiment. The light condensed by the condensing lens 303A is directly irradiated on the subject without passing through a light guide or the like.

  The processor 200 includes a CPU 201B, an image processing circuit 203, and an interface 204, which correspond to the CPU 201, the image processing circuit 203, and the interface 204 of the first embodiment. The CPU 201B outputs various control signals to the CPU 201A in accordance with input signals from the input unit 500.

  Also according to the second embodiment, the CPU 201A and the luminance calculation unit 202A operate in the same manner as the CPU 201 and the luminance calculation unit 202 of the first embodiment, so that substantially the same effect as the first embodiment is obtained. Obtainable.

[Third Embodiment]
Next, an endoscope system according to a third embodiment will be described with reference to FIG. The endoscope system according to the third embodiment is mainly composed of an endoscope 100, a processor 200, a light source device 300, a display 400, and an input unit 500. The form is the same. However, in the third embodiment, as in the second embodiment, the CPU 201A and the luminance calculation unit 202A corresponding to the CPU 201 and the luminance calculation unit 202 in the first embodiment are configured to be connected to the endoscope 100. It is provided inside. The light source device 300 is also built in the endoscope 100.

  In the third embodiment, a plurality (two in this example) of LEDs 302A (first light emitting unit) and 302B (second light emitting unit) are provided as light sources in the light source device 300. This point is different from the above-described embodiment. The light emission amounts Lrgt and Llft of the LEDs 302A and 302B are independently controlled by changing the duty ratio of the pulse width modulation signal in the pulse width modulation devices 301A and 301B, respectively. Light emitted from the LEDs 302A and 302B is irradiated toward the subject by the condenser lenses 303A and 303B.

  The LEDs 302A and 302B are arranged side by side in the pixel line (scanning line) direction (left-right direction) of the image sensor 114. By adjusting the light emission amounts Lrgt and Llft of the LEDs 302A and 302B, it is possible to adjust the unevenness of the screen brightness in the pixel line direction (left and right direction). In the third embodiment, the number of light sources increases in the horizontal direction, but in the vertical direction, the brightness of the screen is adjusted by a single light source as in the above-described embodiment. be able to.

  Note that the luminance calculation unit 202A has a left-side luminance average that is an average of luminances in the left peripheral portion of one frame image in addition to the one-screen luminance average value Bave, the central luminance average value Bcnt, and the peripheral luminance average value Bedg. The value Blft and the right luminance average value Brgt, which is the average luminance of the right peripheral portion of the image of one frame, can be further calculated.

  FIG. 9 shows an operation of the light source device 300 according to the third embodiment. In FIG. 9, the middle graph shows a change in the light emission amount Lrgt of light emitted from the LED 302A (right side), and the lower graph shows a change in the light emission amount Llft of light emitted from the LED 302B (left side). In the example of FIG. 9, the luminance in the vicinity of the screen center of the captured image of one frame is smaller than the luminance in the peripheral portion in the vertical direction of the screen, and the luminance in the peripheral portion on the left side of the screen is the right side of the screen. The control performed when it is larger than the brightness | luminance of the peripheral part is shown. The light emission amounts Lrgt and Llft are both larger in the period T2 in which the screen center is exposed than in the period T1 in which the screen periphery is exposed (Lcntrgt> Ledgrgt, Lcntlft> Ledglft). However, in order to adjust the luminance in the left-right direction, the amount of emitted light Lrgt is generally larger than the amount of emitted light Llft (Lcntrgt> Lcntlft, Ledgrgt> Ledglft).

A control procedure of the light source device 300 in the endoscope system according to the third embodiment will be described with reference to the flowcharts of FIGS. 10A and 10B.
First, the same procedure as steps S11 to S17 of the first embodiment is executed.
Subsequent steps S31 to S34 are procedures for setting the average values Lrgtave and Llfave of the light emission amounts Lrgt and Llft of the left and right LEDs 302A and 302B. In step S17, when the average value “Lave” of the total light emission amount of the LEDs 302A and 302B is calculated, subsequently, in step S31, the average luminance value (right luminance average value on the right side) of the obtained image of one frame. ) Brgt is compared with the average luminance value (left luminance average value) Blft on the left side of the image. When Brgt is greater than Blft by a predetermined value or more, or when Brgt is smaller than the Blft by a predetermined value or more, the average value Lrgtave of the emitted light amount Lrgt of the LED 302A when exposing the position on the right side of the screen is compared with the initial value. Increase or decrease (step S32). On the other hand, when the ratio of Brgt to Blft is within a predetermined range, the average value Lrgtave of the emitted light amount Lrgt is not changed (step S33).

  When the average value Lrgtave of the emitted light amount Lrgt of the right LED 302A is determined in this way, a value obtained by subtracting the emitted light amount Lrgtave from twice the average emitted light amount Lave is calculated as an average value Llfave of the emitted light amount Llft of the left LED 302B. (Step S34). By setting the light emission amounts Lrgtave and Llfave in this way, the average luminance of the entire screen can be maintained at a constant value even if the average values Lrgtave and Llfave of the light emission amount change.

  Subsequent steps S18A to S21B are operations corresponding to steps S18 to S21 of the first embodiment, and the amount of light emitted from the LEDs 302A and 302B when exposing the central portion of the screen and the peripheral portion in the vertical direction of the screen. This is an operation for adjusting the amount of light emitted by the LEDs 302A and 302B during exposure. Steps S18 to S21 in the first embodiment are for adjusting the amount of light emitted from a single LED 302, whereas steps S18A to S21B in the second embodiment are the steps of two LEDs 302A and 302B. Each is different in that the amount of emitted light is adjusted.

  In step S18A, the magnitude relation between the central part average brightness value Bcnt calculated by the brightness calculating unit 202A and the peripheral part average brightness value Bedg is determined (step S18A). When Bcnt is extremely large compared to Bedg (for example, 100 times or more), or when Bcnt is extremely small compared to Bedg (for example, 1/100 or less), when exposing the central portion of the screen The light emission amounts Lcntrgt and Lcntlft of the LEDs 302A and 302B are increased or decreased (steps S19A and 19B). Conversely, when the ratio of Bcnt to Bedg is within a predetermined range, the light emission amounts Lcntrgt and Lcntlft are not changed (steps S20A and 20B).

  Thus, when the light emission amounts Lcntrgt and Lcntlft of the LEDs 302A and 302B when exposing the central portion of the screen are determined, the value obtained by subtracting the light emission amount Lcntrgt from twice the average light emission amount Lrgtave is used when exposing the peripheral portion of the screen. The light emission amount Ledgrgt of the LED 302A is calculated. Also, a value obtained by subtracting the emitted light amount Lcntlft from twice the average emitted light amount Llfave is calculated as the emitted light amount Ledglft of the LED 302B when the peripheral portion of the screen is exposed (steps S21A and 21B).

  Imaging in the next frame is performed by the light emission amounts Lcntrgt, Lcntlft, Ledgrgt, and Ledglft thus set. The set light emission amounts Lcntrgt, Lcntlft, Ledgrgt, Ledglft, and Lave are temporarily stored in a memory (not shown), but a new light emission amount is set at a predetermined timing, and the stored value of the memory is reset each time. (Step S22).

  As described above, in the third embodiment, in addition to obtaining the same effect as that of the above-described embodiment, it is possible to further correct the uneven brightness of the image in the left-right direction. In order to adjust the brightness in the horizontal direction, a plurality of light sources are included in the horizontal direction, but a single light source may be used in the vertical direction. For this reason, it is possible to suppress whiteout and blackout in an image while suppressing an increase in the number of light sources.

  As mentioned above, although several embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  For example, in the above embodiment, the image pickup device adopts a progressive method, that is, a method in which adjacent scanning lines are sequentially operated from the top. However, the present invention is also applied to an image pickup device to which so-called interlaced scanning is applied. Embodiments can be applied.

  In the first and second embodiments, the brightness of the screen center (first area) is compared with the brightness of the screen (vertical direction) peripheral part (second area). In the above description, the light emission amount of the light source device 300 is changed by comparison with the light emission amount of the light source device 300 at the periphery of the screen. Thus, by calculating the luminance in the two areas and changing the amount of light emitted in the two areas, the effect of suppressing the whiteout or blackout of the image can be sufficiently obtained, but the number of areas for calculating the luminance can be reduced. Further increase is possible. By dividing the image area into three or more instead of two (for example, upper / center / lower), the amount of emitted light can be adjusted more precisely, and the resulting image can be made more natural and easy to see. it can.

DESCRIPTION OF SYMBOLS 1 ... Endoscopy system, 100 ... Endoscope, 101 ... Insertion part, 102 ... Hand operation part, 102A ... Bending operation knob, 103 ... Bending part, 104 ... Tip part, 105 ... Universal cable, 106 ... Connector part, DESCRIPTION OF SYMBOLS 111 ... Light guide, 112 ... Condensing lens, 113 ... Objective lens, 114 ... Image pick-up element, 115 ... A / D conversion circuit, 116 ... Signal processing circuit, 200 ... Processor, 202, 202A, ... Luminance calculation part, 203 ... Image processing circuit, 204, interface (I / F), 300, light source device, 303A, 303B, condensing lens, 400, display, 500, input unit.

Claims (10)

An endoscope having an imaging unit;
A light source device for supplying irradiation light for irradiating a subject;
A luminance calculation unit for calculating the luminance of the image of the subject obtained from the imaging unit;
A control unit for controlling the light source device,
The imaging unit is configured to perform imaging by a rolling shutter system that sequentially exposes a plurality of blocks at different timings,
The luminance calculation unit calculates the luminance in the first area of the image and the luminance in the second area in which the block is different from the first area of the image,
The control unit compares the luminance in the first region with the luminance in the second region, and based on the comparison result, the control unit is a light emission amount of the light source device when exposing the first region. An endoscope system, wherein a light emission amount is changed in comparison with a second light emission amount that is a light emission amount of the light source device when exposing the second region.   The endoscope system according to claim 1, wherein the first region is located closer to a center side in the image than the second region. The controller is
Decreasing the second emitted light amount when increasing the first emitted light amount,
The endoscope system according to claim 1 or 2, wherein the second light emission amount is increased when the first light emission amount is decreased.   The said control part changes the said 1st emitted light amount so that the sum of the said 1st emitted light amount and the said 2nd emitted light amount may become substantially the same before and after the change of the said 1st emitted light amount. Endoscope system.   The internal control according to claim 1, wherein the control unit compares a luminance average value that is an average value of luminance in the entire image with a target value, and controls an exposure time in the imaging unit based on the comparison result. Mirror system.   The endoscope system according to claim 5, wherein the control unit changes a timing for starting a period for setting the first light emission amount in accordance with a change in an exposure period for exposing the subject. In the period during which the light source device exposes the first region,
A first period in which the amount of emitted light is continuously increased from a first value toward a second value;
A second period for maintaining the amount of emitted light at the second value;
The endoscope system according to claim 1, wherein the emitted light quantity is changed so as to have a third period in which the emitted light quantity is continuously decreased from the second value toward the third value.   The endoscope system according to claim 7, wherein the first period and the third period have a length in which exposure of a plurality of scanning lines is performed. The light source device includes a plurality of light emitting units,
The control unit includes a luminance in a third region illuminated by one first light emitting unit of the plurality of light emitting units, and a brightness different from the first light emitting unit of the plurality of light emitting units. 2. The luminance in the fourth region illuminated by the two light emitting units is compared, and the light emission amount of the first light emitting unit and the light emission amount of the second light emitting unit are controlled according to the comparison result. The endoscope system described in 1.   The endoscope system according to claim 9, wherein the plurality of light emitting units are arranged along a scanning line direction of the imaging unit.

Images