JP2005296027A - Endoscope light source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize an endoscope light source device capable of controlling illumination light irradiation so as to improve the resolution of a still image without reducing the moving image rate.
[Solution]
The second light L2 is not irradiated on the subject in the even field period T3 in the charge reading period TR by the trigger signal S1, and the CCD is not exposed during that time. In addition, the trigger signal S1 changes the charge reading method from field reading in which all image signals are read out every field period to frame reading in which all image signals are read out in one frame period T1. As a result, in the odd-numbered field period T2 and the even-numbered field period T3 of the charge reading period TR, the charges generated by the odd-numbered and even-numbered lines are read out, and a still image with high resolution is formed. Further, since the frame reading is used only for forming a still image in the charge reading period TR, flickering due to a decrease in the moving image rate is not caused.
[Selection] Figure 4

Description

  The present invention relates to an endoscope light source device, and more particularly, to an electronic endoscope light source device capable of controlling irradiation light irradiation to improve the resolution of a subject image.

  An electronic endoscope apparatus is generally composed of a processor including a light source for illuminating a body tissue that is a subject, and a video scope including an image sensor. Illumination light from the light source is applied to the subject from the video scope via the light guide. Then, the video signal obtained by the image sensor is transmitted to the processor, and a predetermined process is performed on the video signal in the processor, whereby the subject image is displayed on the monitor.

  An interline CCD is widely used as an image sensor used in an electronic endoscope apparatus. Then, generally, a moving image is formed by so-called field reading (pixel mixture reading), in which charges that are imaged by the color difference sequential method and accumulated in the image sensor are added and read out by two lines.

On the other hand, as a method of reading out the charges accumulated in the interline CCD in order to form a still image, after providing a light shielding period for reading, the signal charges of the odd and even lines of the image sensor are There is known a so-called frame reading (all pixel reading) in which reading is sequentially performed one field period at a time and reading of all charges is completed in one frame period (see, for example, Patent Document 1). By this frame reading, a still image with higher resolution than that of field reading is realized. A so-called frame readout (all pixel readout) is known in which the signal charges of the odd and even lines of the imaging device are sequentially read out one field period at a time and the readout of all charges is completed in one frame period (for example, Patent Document 1). reference).
Japanese Patent No. 3370871 (FIGS. 4 and 5)

  In the diaphragm controlled by the motor, since the response time is long, it is impossible to provide a light shielding period corresponding to one field period required for frame reading. Further, even if the latest liquid crystal element is used, a short light shielding time required for frame reading cannot be realized.

  On the other hand, by using a light shielding means such as a rotating plate, a short light shielding time enabling frame reading can be realized. However, in this case, since the time required to read out all charges is a frame period, which is longer than that in field readout, the moving image rate is lowered, and flickering due to frame afterimage is likely to occur when displaying a moving image.

  The present invention realizes an endoscope light source device capable of controlling illumination light illumination so as to improve the resolution of a still image without reducing the moving image rate while using a general-purpose light shielding means. Objective.

  The light source device of the present invention is used in an electronic endoscope device that includes an interline type imaging device and forms a moving image by adding and reading out charges for two vertical lines accumulated in the imaging device. It is a light source device. The light source device includes: a light source that emits illumination light for illuminating a subject; an illumination light splitting unit that divides the illumination light emitted by the light source into two lights, a first light and a second light; Irradiation control means for alternately passing and shielding one light and the second light in a cycle of one frame period, and a light shielding means capable of shielding only the second light. Then, in the charge reading period, which is one frame period immediately after the freeze operation by the user for forming a still image, all charges obtained during the same exposure of the image sensor are read for each odd line and even line of the image sensor. Therefore, the light shielding unit of the light source device shields the second light in accordance with the freeze operation for at least one field period in the charge readout period.

  The irradiation control means includes, for example, a rotating plate having a passage portion that allows the first light and the second light to pass therethrough and a light shielding portion that shields light, and a rotating plate driving means that drives the rotating plate. In this case, it is preferable that the rotating plate driving means controls the rotating plate so that the rotating plate makes one rotation in one frame period. In addition, it is desirable that the time for blocking the first light and the second light can be adjusted depending on the size of the light blocking portion.

  The light shielding means is, for example, a light shielding liquid crystal.

  The light source device preferably includes an optical path adjusting unit that adjusts an optical path between the first light and the second light, and the optical path adjusting unit includes, for example, a mirror.

  The illumination light splitting means is, for example, a polarization beam spiriter.

  The electronic endoscope apparatus of the present invention includes an interline type image pickup device, and forms a moving image by adding and reading out charges for two lines in the vertical direction accumulated in the image pickup device. An electronic endoscope apparatus includes a light source that emits illumination light for illuminating a subject, and an illumination light splitting unit that divides the illumination light emitted by the light source into two lights, a first light and a second light Irradiating control means for alternately passing and shielding the first light and the second light in a cycle of one frame period, a shielding means capable of shielding only the second light, and a user for forming a still image And freeze operation detecting means for detecting the freeze operation by. Then, when the freeze operation detecting means detects the freeze operation, in the charge readout period, which is one frame period immediately after the freeze operation, all charges obtained during the same exposure of the image sensor are obtained for each odd line and even line of the image sensor. In order to enable reading, the light blocking means blocks the second light in accordance with the freeze operation for at least one field period in the charge reading period.

  ADVANTAGE OF THE INVENTION According to this invention, the light source device for endoscopes which can perform illumination light irradiation control so that the resolution of a still image can be improved, without reducing a moving image rate, using a general-purpose light-shielding means is realizable. .

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of an electronic endoscope apparatus 10 in the present embodiment.

  The electronic endoscope apparatus 10 includes a video scope 20 used for imaging in a body cavity of a patient, and a processor 30 that supplies illumination light to the video scope 20 and processes an image signal sent from the video scope 20. . The video scope 20 is detachably connected to the processor 30, and a monitor 60 is connected to the processor 30.

  The processor 30 is provided with a light source device 31 that emits illumination light. The light source device 31 includes a light source 32, first and second polarization beam spiriters 33 and 34, a light shielding liquid crystal 35, a rotating plate 36, and the like. When a light source lighting switch (not shown) is operated to supply power, the light source 32 emits illumination light for illuminating the subject. The emitted illumination light reaches the rotating plate 36 via the first and second polarized beam spiriters 33 and 34 and the light shielding liquid crystal 35 as will be described later. The rotating plate 36 is driven by a motor 37 to block and pass illumination light for a certain period of time. The illumination light that has passed through the rotating plate 36 is incident on the dimming diaphragm 45 after the optical path is adjusted by the optical path control unit 38. The illumination light whose light amount is adjusted by the light control diaphragm 45 enters the incident end 12 </ b> A of the light guide 12 through the light guide lens 40. The light guide 12 transmits the illumination light to the distal end portion of the video scope 20 having the observation site, and the illumination light passing through the light guide 12 is emitted from the emission end 12B to the observation site.

  Illumination light reflected from the observation site, which is a subject, passes through an objective lens (not shown) and a color filter (not shown) and reaches the light receiving surface of the interline type CCD 22, whereby the subject image is received by the CCD 22. Formed on the surface. In the CCD 22, an image signal of a subject image corresponding to the color passing through the color filter is generated by photoelectric conversion. Here, the NTSC system is applied as the color television system. By adding the image signals generated by the odd lines and the even lines of the CCD 22, the same of the CCD 22 is obtained every one field period, that is, every 1/60 second interval. All pixel signals obtained at the time of exposure are sequentially read out and sent to the initial signal processing circuit 24.

  In the video scope 20, a scope control unit 26 that controls the entire video scope 20 and an EEPROM 28 in which data related to characteristics and signal processing of the video scope 20 are stored in advance are provided. The scope control unit 26 sends a control signal to the initial signal processing circuit 24 and reads data from the EEPROM 28 as appropriate. For example, when the video scope 20 is connected to the processor 30, the scope control unit 26 reads the frame rate information of the CCD 22 from the EEPROM 28 and sends it to the initial signal processing circuit 24. The initial signal processing circuit 24 sends the frame rate information of the CCD 22 to the dimming control unit 41 in the system control circuit 44 on the processor 30 side. The dimming control unit 41 controls the motor 37 to rotate the rotating plate 36 once in one frame period based on the received frame rate information of the CCD 22.

  In the initial signal processing circuit 24, the read image signal is subjected to amplification processing, and further converted from an analog signal to a digital signal. Various processes such as white balance adjustment are performed on the digital image signal to generate a luminance signal Y and color difference signals Cb and Cr. The luminance signal Y and the color difference signals Cb and Cr are sent to the processor signal processing circuit 48 of the processor 30, converted into a video signal such as an NTSC signal, and output to the monitor 60. As a result, the subject image is displayed on the monitor 60 in real time.

  The video scope 20 is provided with a freeze button 25. When the user presses the freeze button 25, a trigger signal for forming a still image is transmitted to the dimming control unit 41 via the scope control unit 26. The dimming control unit 41 transmits a signal for turning off the light shielding liquid crystal 35 to the light shielding liquid crystal 35 based on the received signal. As a result, after the light shielding liquid crystal 35 is switched from the on state to the off state, a still image is displayed as described later.

  A system control circuit 44 including a dimming control unit 41 and a CPU 42 controls the entire processor 30 and outputs control signals to the light source device 31, the dimming diaphragm 45, the timing control circuit 46, and the like. The ROM 43 in the system control circuit 44 stores a program related to the control of the processor 30. From the timing control circuit 46, a clock pulse for adjusting the signal processing timing is output to each circuit in the processor 30, and a synchronization signal added to the video signal is sent to the processor signal processing circuit 48.

  FIG. 2 is a diagram showing the light source device 31. FIG. 3 is a view showing the rotating plate 36.

  On the optical path of the illumination light emitted from the light source 32, a first polarized beam spiriter 33 is provided. Only the P wave component of the illumination light incident on the first polarization beam spiriter 33 is reflected by the first polarization beam spiriter 33 as the first light L1 and reaches the rotating plate 36. On the other hand, the S wave component of the illumination light passes through the first polarization beam spiriter 33 and enters the second polarization beam spiriter 34 as the second light L2. The second light L2 incident on the second polarized beam spiriter 34 reaches the light shielding liquid crystal 35 by reflection. When the light-blocking liquid crystal 35 is in the on state under the control of the light control unit 41, the second light L2 is reflected by the light-blocking liquid crystal 35 and enters the rotating plate 36, and when the light-blocking liquid crystal 35 is in the off state. Does not pass through the light shielding liquid crystal 35 and travel toward the rotating plate 36.

  The rotating plate 36 driven by the motor 37 alternately blocks and passes the first light L1 and the second light L2 by a predetermined time. The surface of the rotating plate 36 has a fan shape and has a light shielding surface 50 that shields the first light L1 and the second light L2 (see FIG. 3). The first light L1 and the second light L2 pass through the rotating plate 36 only when the passage region 52 of the rotating plate 36 is on the optical path. Since the rotating plate 36 makes one rotation every 1 frame period, that is, every 1/30 seconds, the first light L1 and the second light L2 are alternately shielded and passed by a fixed time each in a period of one frame period. Iterate. Both the first light L1 and the second light L2 that have passed through the rotating plate 36 enter the optical path control unit 38. The illumination light (first light L1 and second light L2) irradiated to the subject during one frame period is adjusted by adjusting the central angle α of the light shielding surface 50 and changing the size of the light shielding surface 50. Can be adjusted, and the amount of illumination light applied to the subject can be adjusted.

  The optical path control unit 38 includes first to third reflection mirrors 54 to 56 and a half prism 58. When the first light L <b> 1 passes through the rotating plate 36, it is reflected by the first reflecting mirror 54 and enters the half prism 58. Further, the first light L 1 is reflected by the half prism 58 to change the optical path, and is emitted from the optical path control unit 38 toward the dimming diaphragm 45. On the other hand, the second light L 2 is reflected by the second and third reflection mirrors 55 and 56 after passing through the rotating plate 36 and enters the half prism 58. The optical path of the second light L2 is not changed by the half prism 58. As a result, the first light L1 and the second light L2 travel on the same optical path when they exit the half prism 58. The first light L1 is used for exposure of the CCD 22 in the odd field, and the second light L2 is used for exposure in the even field.

  FIG. 4 is a timing chart showing illumination light irradiation.

  As described above, the frame period T1 is 1/30 second, and is composed of two field periods of an odd field period T2 and an even field period T3 of 1/60 seconds. When the freeze button 25 is pressed and a trigger signal S1 for displaying a still image is transmitted to the dimming control unit 41, the light shielding liquid crystal 35 has a charge readout period TR that is a frame period immediately after the trigger signal S1. And is controlled to be in the off state. The start of the OFF state of the light shielding liquid crystal 35 is synchronized with the start of the odd field period T2 immediately after the trigger signal S1 by the dimming control unit 41. As a result, since the second light L2 is shielded by the light shielding liquid crystal 35 in the frame period T1, the irradiation amount of the first light L1 incident on the rotating plate 36 is constant, whereas the second light L2 is constant. L2 is not applied to the rotating plate 36 during the frame period T1.

  For this reason, the first light L1 after passing through the rotating plate 36 is used for exposure of the CCD 22 every odd field period T2, and the light quantity change is constant with the period of the frame period T1 as opposed to the second light L2. In the even field period T3 included in the charge reading period TR, the subject is not irradiated, and the CCD 22 is not exposed during this period.

  When the scope control unit 26 receives the trigger signal S1, the scope control unit 26 temporarily converts the image signal readout method by transmitting an instruction signal to the CCD 22 via the initial signal processing circuit 24. In other words, the field reading for reading out the image signal for one frame every field period is changed to the frame reading for reading out the image signal for one frame in one frame period TR1. The start of the frame reading is synchronized with the start of the odd field period T2 immediately after the trigger signal S1, that is, the start of the charge reading period TR.

  As described above, since the CCD 22 is not exposed in the even field period T3 and the charge readout method is changed to the frame readout, only the charges generated by the odd lines of the CCD 22 are read out. The charge generated by the line is read out. Based on the total charges read for each line in this way, the processor signal processing circuit 48 generates a video signal for displaying a still image. A still image is displayed on the monitor 60 by this video signal. Further, since the video signal of the still image is recorded in a memory (not shown) in the system control circuit 44, the printer (not shown) prints the still image by the user's print start operation.

  By reading the frame, the charges of the odd and even lines are read without being added, so that a still image with higher resolution than that by the field reading is formed. Frame reading is used only for forming a still image in one frame period TR, and field reading is used for forming a moving image for displaying a moving image other than displaying the formed still image. For this reason, the moving image rate is not lowered by using the frame reading, and the user is not perceived to flicker.

  As described above, according to the present embodiment, a still image with high resolution can be obtained while preventing flicker without reducing the moving image rate by using the light shielding liquid crystal 35 and the rotating plate 36 that are general-purpose light shielding means. Thus, an endoscope light source device capable of controlling illumination light irradiation can be realized. Furthermore, since the response speed can be afforded by dividing the optical path of the illumination light into two, the range of selection of components constituting the light source device is widened.

The configurations of the irradiation control means and the light shielding means are not limited to the rotating plate 36, the motor 37 that drives the rotation plate 36, and the light shielding liquid crystal 35. For example, the light shielding plate and the optical paths of the first light L1 and the second light L2 are used. The VCM may be driven so as to be inserted / removed appropriately. In this case, when the freeze button 25 of the video scope 20 is pressed, the still image mode is entered from the exposure timing of the CCD 22 by the first light L1 immediately after that, but the normal by the second light L2 before that. Upon completion of the exposure operation, the second light L2 is shielded by controlling the light shielding plate by the VCM, and when the still image mode is completed, the shielding of the second light L2 by the VCM is canceled, so that the original VCM It is possible to operate without the high performance required for operation.

  The arrangement of the mirrors of the optical path control means is not limited to this embodiment. For example, the first light L1 from the first reflection mirror 54 and the second light from the second reflection mirror 55 are used by using a DMD (digital micromirror device) as the third reflection mirror 56 except for the half prism 58. Any of L2 may be optically adjusted by the third reflecting mirror 56.

It is a block diagram of an endoscope apparatus. It is a figure which shows a light source device. It is a figure which shows a rotating plate. It is a timing chart which shows irradiation of illumination light.

Explanation of symbols

10 Electronic Endoscope 20 Videoscope 22 CCD (Imaging Device)
25 Freeze button (freeze motion detection means)
26 Scope control unit (freeze motion detection means)
30 processor 31 light source device 32 light source 33 first polarized beam spiriter (illumination light splitting means)
34 Second polarized beam splitter (illumination beam splitting means)
35 Light-shielding liquid crystal (light-shielding means)
36 Rotating plate (irradiation control means)
37 Motor (rotary plate drive means / irradiation control means)
38 Optical path controller (optical path adjustment means)
41 Light control unit 50 Light shielding surface (light shielding portion)
52 Passing area (passing part)
54-56 1st-3rd reflective mirror (optical path adjusting means / mirror)
58 Half prism (light path adjustment means)
L1 First light L2 Second light TR Charge readout period

Claims (8)

A light source device used in an electronic endoscope device that includes an interline type imaging device and forms a moving image by adding and reading out charges for two vertical lines accumulated in the imaging device,
A light source that emits illumination light to illuminate the subject;
Illumination light dividing means for dividing the illumination light irradiated by the light source into two lights, a first light and a second light;
Irradiation control means for alternately passing and blocking the first light and the second light at a cycle of one frame period;
A light shielding means capable of shielding only the second light,
In a charge readout period, which is one frame period immediately after a freeze operation by a user for forming a still image, all charges obtained during the same exposure of the image sensor are read for each odd line and even line of the image sensor. To enable
The light source device, wherein the light shielding unit shields the second light in accordance with the freeze operation for at least one field period in the charge reading period.   The irradiation control means includes a rotating plate having a passage portion that allows the first light and the second light to pass therethrough and a light shielding portion that shields light, and a rotating plate driving means that drives the rotating plate. The light source device according to claim 1.   The light source device according to claim 2, wherein the rotating plate driving unit controls the rotating plate so that the rotating plate makes one rotation in one frame period.   The light source device according to claim 3, wherein a time for blocking the first light and the second light can be adjusted by a size of the light blocking portion.   The light source device according to claim 1, wherein the light shielding unit is a light shielding liquid crystal.   The light source device according to claim 1, further comprising: an optical path adjusting unit that adjusts an optical path between the first light and the second light, wherein the optical path adjusting unit includes a mirror.   The light source device according to claim 1, wherein the illumination light splitting unit is a polarization beam spiriter. An electronic endoscope apparatus that includes an interline type image sensor and forms a moving image by adding and reading out charges for two vertical lines accumulated in the image sensor,
A light source that emits illumination light to illuminate the subject;
Illumination light dividing means for dividing the illumination light irradiated by the light source into two lights, a first light and a second light;
Irradiation control means for alternately passing and blocking the first light and the second light at a cycle of one frame period;
A light shielding means capable of shielding only the second light;
A freeze operation detecting means for detecting a freeze operation by a user for forming a still image,
When the freeze operation detecting means detects the freeze operation, in the charge reading period, which is one frame period immediately after the freeze operation, all charges obtained during the same exposure of the image sensor are converted into odd lines and even lines of the image sensor. In order to be able to read line by line,
The electronic endoscope apparatus, wherein the light shielding means shields the second light in accordance with the freeze operation for at least one field period in the charge reading period.

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