JP6231271B2 - Electronic endoscope system - Google Patents

Description

  The present invention relates to an electronic endoscope system that performs stroboscopic copying by intermittently irradiating illumination light, and more particularly to a laryngeal stroboscope that performs stroboscopic copying inspection of vocal cords.

  For example, in an electronic endoscope system that performs laryngeal stroboscopic copying, a subject's voice is detected using a microphone, and illumination light is intermittently emitted according to the fundamental frequency of the voice, so that the state of the vocal cords in a predetermined phase, A slow motion image of a vocal cord is taken (Patent Document 1).

Japanese Patent Laid-Open No. 2004-166761

  For the conventional laryngeal strobe copy inspection, an electronic scope using a fiberscope or a CCD having a global shutter function is used. However, in recent years, with the widespread use of CMOS image sensors, the use of CMOS image sensors is also required in laryngeal scopes. However, since a small CMOS image sensor uses a rolling shutter and does not have a global shutter function, it cannot be used for strobe copy inspection in the same manner as a CCD.

  An object of the present invention is to appropriately obtain a stroboscopic image in an electronic endoscope using a rolling shutter.

  An electronic endoscope system according to the present invention includes an imaging unit that performs imaging using a rolling shutter, and an illumination unit that can intermittently illuminate illumination light for stroboscopic imaging. The image reading is started at the end of the light irradiation, and the illumination unit is prohibited from irradiating the illumination light until the image reading is completed.

  The electronic endoscope system also includes an image memory that sequentially and temporarily holds images read in the stroboscope photographing, and an image output unit that outputs the latest image held in the image memory in synchronization with the video signal. It is preferable.

  The electronic endoscope system preferably further includes frequency detection means for detecting the vibration frequency of the object to be photographed, and the illumination light irradiation timing in the stroboscope photographing is determined based on the fundamental frequency detected by the frequency detection means. It is preferable.

  According to the present invention, it is possible to appropriately obtain a stroboscopic image even in an electronic endoscope using a rolling shutter.

It is a block diagram which shows the structure of the electronic endoscope system which is one Embodiment of this invention. 6 is a timing chart showing pixel signal readout timing and image output timing from an image sensor during normal endoscopic image capturing. 5 is a timing chart showing the timing of light emission in stroboscope photography and the timing of reading out pixel signals from the image sensor together with the sound waveform. It is a timing chart which shows the output timing of each frame image in strobe mode. It is a flowchart which shows the processing operation of the processor apparatus in strobe mode. It is a flowchart which shows the processing operation of the strobe light-emitting device in strobe mode.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an electronic endoscope system according to an embodiment of the present invention.

  An electronic endoscope system 10 according to the present embodiment includes an electronic scope 11, a processor device 12 to which the electronic scope 11 is detachably connected, a monitor 13 that displays an image from the processor device 12, and illumination for strobe copying. A strobe light emitting device 14 that supplies light to the electronic scope 11 is configured. In the present embodiment, the electronic scope 11 is a laryngeal endoscope, for example.

  An imaging element (CMOS image sensor) 15 using a rolling shutter is mounted at the tip of the electronic scope 11 and is driven and controlled by a drive signal from a drive circuit 16 provided in the processor device 12, for example. In the image sensor 15, imaging at a predetermined rate is performed through the objective lens 15 </ b> A, and the detected image signal is sent to the upstream signal processing circuit 17 of the processor device 12. In the pre-stage signal processing circuit 17, the image signal is converted into a digital signal and subjected to predetermined image processing, and is sequentially stored in the frame memory 18 sequentially. The images (frame images) stored in the frame memory 18 are sequentially sent to the subsequent signal processing circuit 19, converted into a video signal of a predetermined standard, for example, and output to an output device such as the monitor 13. Note that the drive circuit 16, the pre-stage signal processing circuit 17, the frame memory 18, and the post-stage signal processing circuit 19 are controlled based on various synchronization signals from the timing controller 20.

  Further, the photographing of the subject by the image sensor 15 is performed under illumination light supplied to the tip of the electronic scope 11 through the light guide 21 and irradiated from the tip of the electronic scope through the illumination lens 21A. Illumination light is supplied to the light guide 21 from the light source unit 22 of the processor device 12 or the light source unit 23 of the strobe light emitting device 14. FIG. 1 shows a connection state when the strobe copy inspection is performed (when the strobe mode is selected), and the light guide 21 is connected to the light source unit 23 of the strobe light emitting device 14, but when normal photographing is performed (normal). At the time of mode selection, for example, the light guide 21 is connected to the light source unit 22 of the processor device 12.

  The light source unit 22 and the timing controller 20 of the processor device 12 are controlled by a system controller 24 that controls the entire processor device. The system controller 24 is provided with various switches and indicators. For example, a front panel 25 disposed on the front surface of the processor device 12 is connected. The system controller 24 can select various processes and switch various modes by a switch operation of the front panel 25 by the user.

  In addition, the processor device 12 of this embodiment is electrically connected to the strobe light emitting device 14, and the processor device 12 is provided with a light emission signal detection unit 26 that receives and detects strobe light emission pulses from the strobe light emitting device 14. . When the light emission signal detection unit 26 detects a strobe light emission pulse, a detection signal is output to the timing controller 20, and the timing of the drive signal of the image sensor 15 generated by the drive circuit 16 is changed as will be described later. The strobe light emission pulse is a pulse signal corresponding to the illumination light supply period supplied from the light source unit 23 to the light guide 21 as will be described later, and is generated by the main control unit 27 of the strobe light emitting device 14.

  The strobe light-emitting device 14 is provided with a microphone 28 that collects sound emitted by the subject, and the pitch (fundamental frequency) and phase are detected by the sound pitch detection circuit 29. For example, the detected audio pitch and phase are output to the main control unit 27 as a pitch detection pulse to be described later, and the main control unit 27 controls light emission from the light source unit 23 based on the pitch detection pulse and also uses strobe light emission. A pulse signal is generated.

  The main control unit 27 is provided with various switches and indicators, and is connected to, for example, a front panel 30 disposed in front of the strobe light emitting device 14. In the main control unit 27, based on the switch operation of the front panel 30 by the user, a selection is made between taking a still image with a predetermined phase or taking a slow motion image with the phase moving at a constant pitch, or taking a still image. The phase is selected at, and a pitch detection pulse corresponding to the detected pitch and phase is generated in accordance with these selections.

  In addition, the strobe light emitting device 14 of the present embodiment is provided with a prohibition signal detection unit 31. The prohibition signal detector 31 receives a strobe light emission prohibition pulse from the timing controller 20 of the processor device 12. When the prohibition signal detection unit 31 detects a strobe light emission prohibition pulse, the main control unit 27 prohibits light emission of the light source unit 23.

  Next, referring to the timing charts of FIG. 1 and FIG. 2, the timing of reading out pixel signals from the image sensor (CMOS) 15 using the rolling shutter during normal shooting (normal mode), and the frame memory 18 The timing of storing the frame image, the timing of outputting each frame image to the subsequent signal processing circuit 19, that is, the timing of outputting each frame image to the monitor 13 will be described.

  FIG. 2A shows the read timing from the image sensor 15 of each line (first to nth lines constituting one frame image) using a rolling shutter, and FIG. A sequence of each frame image (first frame to nth frame) stored in the frame memory 18 corresponding to the reading, FIG. 2C shows a 60 fps video output to the frame memory 18 and the subsequent signal processing circuit 19. The synchronization signal, FIG. 2D, shows a sequence of each frame image that is output from the subsequent signal processing circuit 19 and displayed on the monitor 13 in accordance with the video synchronization signal.

  As shown in FIG. 2, at the time of normal shooting, the readout cycle from the image sensor 15 of each frame (first to nth frames) is synchronized with an output video synchronization signal (for example, 60 fps), and a subsequent signal processing circuit From 19, the image signals of the frames currently read from the image sensor 15 are sequentially output.

  Next, with reference to the timing charts of FIGS. 1, 3, and 4, the stroboscopic photographing process and the output process using the rolling shutter in the present embodiment will be described.

  FIG. 3 is a timing chart showing light emission timing and pixel signal readout timing in the stroboscope photographing (strobe mode) of the present embodiment. 3 (a) shows the basic waveform of the sound collected by the microphone 28, FIG. 3 (b) shows the pitch detection pulse, FIG. 3 (c) shows the strobe light emission pulse, and FIG. 3 (d) shows the rolling. The read timing of each line (first line to nth line) using the shutter, and FIG. 3 (e) show the strobe light emission inhibition pulse output from the timing controller 20 of the processor unit 12.

  FIG. 3 illustrates a shooting process when shooting a still image of a specific phase. Here, the voice pitch detection circuit 29 generates a pitch detection pulse PS at a basic period T (actually a multiple of the basic period) corresponding to a predetermined phase of the voice basic waveform V, and outputs it to the main control unit 27. To do. The main control unit 27 emits the light source unit 23 and supplies the illumination light to the light guide 21 when the pitch detection pulse PS is input and the strobe light emission prohibiting pulse PB is not output from the timing controller 20 of the processor device 12. During this period (strobe light emission period), the strobe light emission pulse PL is set to the high (H) state and is output to the light emission signal detection unit 26 of the processor device 12. When the strobe light emission period ends, the strobe light emission pulse PL is returned to the low (L) state.

  The driving circuit 16 of the processor device 12 starts reading out the pixel signal by the rolling shutter in the image sensor 15 when the falling edge of the strobe light emission pulse PL is detected in the light emission signal detection unit 26, and the timing controller 20 uses the rolling shutter. While the image reading from the image sensor 15 is being performed, the strobe light emission prohibiting pulse PB is output to the prohibition signal detecting unit 31 of the strobe light emitting device 14.

  With the above configuration, in this embodiment, regardless of the video synchronization signal, the shooting frame rate is determined by the relationship between the output timing of the pitch detection pulse generated based on the audio basic waveform and the readout period required to read out one screen. It is determined. Further, strobe emission (irradiation of illumination light) of the light source unit 23 is prohibited while image reading is being performed by the image pickup device 15, so that overlapping exposure (double exposure) is prevented. Note that in the strobe mode of this embodiment, the period required to read out one screen is the same as that during normal shooting, but it is not necessarily the same.

  In the example shown in FIG. 3, when the first and third pitch detection pulses PS are input, since the strobe light emission prohibiting pulse PB is low, the strobe light emission pulse PL is generated, and the second and fourth pitch detection pulses PS are generated. Is input, since the strobe light emission inhibition pulse PB is high, the strobe light emission pulse PS is not generated.

  Next, image output processing in the strobe mode of this embodiment will be described with reference to FIGS. 4A shows the strobe light emission pulse PL generated by the main control unit 27, and FIG. 4B shows each line using a rolling shutter that starts in synchronization with the fall of the strobe light emission pulse PL. The readout timing of (the first line to the nth line constituting one frame image) is shown. 4C shows a sequence of each frame image (first frame to third frame) stored in the frame memory 18 in correspondence with the reading of FIG. 4B, and FIG. The video synchronization signal of 60 fps output to the frame memory 18 and the post-stage signal processing circuit 19 is shown. FIG. 4E shows a sequence of each frame image output from the subsequent signal processing circuit 19 and displayed on the monitor 13 in accordance with the video synchronization signal.

  In FIG. 4, since the frame rate of the video synchronization signal is higher than the frame rate of reading from the image sensor 15 based on the strobe light emission pulse PL (frequency of the strobe light emission pulse PL), the synchronization corresponding to the next frame in the video synchronization signal. Even if the signal is output, only the image of the previous frame is stored in the frame memory 18. Therefore, in the image output process of the present embodiment, the image of the immediately preceding frame is output in synchronization with the video synchronization signal until the image of the next frame is stored in the frame memory 18. In the example of FIG. 4, the first frame of the captured image is sequentially output twice and the second frame is output twice in accordance with 60 fps.

  Next, with reference to the flowcharts of FIGS. 1, 5, and 6, the flow of operations in the strobe mode of the processor device 12 and the strobe light emitting device 14 in the electronic endoscope system 10 of the present embodiment will be described.

  FIG. 5 is a flowchart showing the processing operation of the processor device 12 in the strobe mode. This process is started, for example, when the strobe mode is selected by the user or when the connection with the strobe light emitting device 14 is electrically detected.

  In step S100, the reading operation of the image sensor 15 is stopped. Next, in step S102, the output level of the strobe emission inhibition pulse output from the timing controller 20 is set to low (L). In step S104, it is determined whether or not the input of the strobe light emission pulse is high (H) in the light emission signal detection unit 26. If it is not high (H) (in the case of low (L)), that is, the strobe light emission pulse. If there is no input of PL (see FIGS. 3 and 4), the determination in the same step is repeated.

  On the other hand, if it is determined in step S104 that the strobe light emission pulse PL is high (H), that is, the strobe light emission pulse PL has been input, in step S108, the output of the strobe light emission inhibition pulse from the timing controller 20 is high ( H). In step S110, reading of the image sensor (CMOS) 15 using the rolling shutter is started in accordance with the fall of the strobe light emission pulse PL (corresponding to the end of illumination light irradiation), and reading of one screen by the rolling shutter is completed. Then, the process returns to step S102. That is, the output of the strobe light emission prohibiting pulse is changed to low (L) again, and the same processing is repeated in the processor device 12 while the stroboscope photographing is performed.

  FIG. 6 is a flowchart showing the processing operation of the strobe light emitting device 14 in the strobe mode. Similar to the processing operation of the processor device 12 shown in FIG. 5, this processing is started, for example, when the strobe mode is selected by the user or when the connection with the processor device 12 is electrically detected. The

  In step S200, the power source of the strobe light source of the light source unit 23 is turned on. In step S202, the level of the strobe light emission pulse is set to a low (L) state and is output to the light emission signal detection unit 26. In step S204, the audio pitch detection circuit 29 starts analyzing the audio signal from the microphone 28 and detects the audio pitch and phase.

  In step S206, it is determined whether or not the level of the strobe emission prohibiting pulse PB input to the prohibition signal detector 31 is high (H). If the level is high (H) (not low (L)). The determination in the same step is repeated. If it is determined in step S206 that the level of the strobe light emission prohibiting pulse PB is low (L), in step S210, the strobe light emission pulse PL rises at the strobe light emission timing, that is, at the same time as the pitch detection pulse is output. While being raised to a high (H) level, the strobe light from the light source unit 23 is irradiated in step S212.

  When the strobe light emission in step S212 is completed and the supply of illumination light to the light guide 21 is stopped, the process returns to step S202, the strobe light emission pulse PL is returned to the low (L) level again, and so on. Is repeated in the stroboscopic light emitting device 14 while stroboscopic imaging is performed.

  As described above, according to the present embodiment, stroboscopic imaging can be performed at an appropriate timing even in an image sensor using a rolling shutter by starting image reading from the image sensor in accordance with the end of illumination light irradiation. It becomes. Also, the occurrence of double exposure can be prevented by prohibiting illumination light irradiation until image reading is completed.

  In this embodiment, the captured stroboscopic image is stored in the image memory, and the latest image stored in the image memory is output, so that the image can be output to a monitor or the like at the frame rate of the video signal. it can.

  In the present embodiment, description has been made using a configuration for capturing an image of a specific phase. However, when capturing a slow motion image of an observation target (a vocal cord), a cycle in which a pitch detection pulse is output is described. A predetermined amount may be shifted from the basic period.

  The strobe light emitting device of the present embodiment has been described as a configuration in which the light source emits strobe light. For example, a normal lamp is used, and light is temporarily emitted using a mechanical shutter mechanism such as a rotary shutter or a diaphragm blade. Therefore, the illumination light supplied to the light guide can be made intermittent by blocking light. Further, the light source unit of the strobe light emitting device can be configured to continuously supply illumination light, and the strobe light emitting device can be used even in the normal mode. Further, the function of the strobe light emitting device of this embodiment can be provided integrally with the processor device.

  Note that the present embodiment is not limited to a laryngeal scope as long as stereoscopy of an observation object is performed.

DESCRIPTION OF SYMBOLS 10 Electronic endoscope system 11 Electronic scope 12 Processor apparatus 13 Monitor 14 Strobe light-emitting device 15 Imaging element (CMOS)
16 drive circuit 18 frame memory (image memory)
DESCRIPTION OF SYMBOLS 20 Timing controller 21 Light guide 23 Light source part 26 Light emission signal detection part 27 Main control part 28 Microphone 29 Sound pitch detection circuit 31 Prohibition signal detection part

Claims (3)

Imaging means for taking an image using a rolling shutter;
Illuminating means capable of intermittently illuminating illumination light for stroboscopic imaging based on a sound pitch detected by a microphone ;
A timing controller for controlling the imaging means ,
The timing controller transmits a light emission prohibiting pulse for prohibiting the emission of the illumination light to the illumination unit while the image reading from the imaging unit is being performed,
When the period from emission of the illumination light to the image reading of the imaging unit is completed it is longer than the basic period of the speech pitch,
Said image pickup means in a stroboscope photography started out looking image read in accordance with the irradiation end of the illumination light, until the image readings out is completed, the illumination means the illumination light by the emission prohibition pulse There electronic endoscope system characterized by that will be controlled not irradiated.   An image memory for temporarily and temporarily holding images read out in the stroboscopic photographing, and an image output means for outputting the latest image held in the image memory in synchronization with a video signal. Item 2. The electronic endoscope system according to Item 1.   The frequency detection means for detecting the vibration frequency of the object to be imaged is provided, and the irradiation timing of the illumination light in the stroboscopic imaging is determined based on the fundamental frequency detected by the frequency detection means. The electronic endoscope system according to claim 1 or 2.

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