Light source device having illumination controller controlling multiple light sources in multiple states, control method of the light source, and endoscope system having the light source

A light source device includes: a first light emitter configured to emit first light; a second light emitter configured to emit second light having an identical color component to the first light; and an illumination controller configured to cause, after causing the first light emitter to emit the first light, the second light emitter to emit the second light according to a set light amount in a state in which the first light emitter is caused to emit the first light.

BACKGROUND

1. Technical Field

The present disclosure relates to a light source device, a control method of a light source, and an endoscope system.

2. Related Art

In the field of medicine, endoscope systems are used to observe the inside of a subject. Generally, an endoscope captures an in-vivo image by inserting a long and thin flexible insertion portion into the body of a subject, such as a patient, by illuminating with illumination light supplied by a light source device from a distal end of this insertion portion, and by receiving reflected light of this illumination light with an imaging unit at the distal end of the insertion portion. The in-vivo image captured by the imaging unit of the endoscope is subjected to predetermined image processing by a processing device of the endoscope system, and then displayed on a display of the endoscope system. A user, such as a medical doctor, observes an organ of the subject based on the in-vivo image displayed on the display.

As for the light source device that emits illumination light, for example, a light source device in which plural light sources emitting the same light are provided to expand a dynamic range of a light amount control has been disclosed, for example, in JP-A-2012-245349. Moreover, in the technique disclosed in JP-A-2012-245349, light emitting order of the light sources is determined based on cumulative light emitting time of the respective light sources.

SUMMARY

In some embodiments, a light source device includes: a first light emitter configured to emit first light; a second light emitter configured to emit second light having an identical color component to the first light; and an illumination controller configured to cause, after causing the first light emitter to emit the first light, the second light emitter to emit the second light according to a set light amount in a state in which the first light emitter is caused to emit the first light.

In some embodiments, provided is a control method of a light source including a first light emitter configured to emit first light; a second light emitter configured to emit second light having an identical component to the first light. The method includes: causing the first light emitter to emit the first light; and causing the second light emitter to emit the second light according to a set light amount in a state in which the first light emitter is caused to emit the first light.

In some embodiments, an endoscope system includes: an endoscope; and a light source device that includes a first light emitter configured to emit first light to be supplied to the endoscope; a second light emitter configured emit second light having an identical color component to the first light; and an illumination controller configured to cause, after causing the first light emitter to emit the first light, the second light emitter to emit the second light according to a set light amount in a state in which the first light emitter is caused to emit the first light.

DETAILED DESCRIPTION

Hereinafter, modes (hereinafter, “embodiments”) to implement the present disclosure will be explained. In the embodiments, a medical endoscope system that captures and displays an image of an inside of a subject, such as a patient will be explained as an example of a system including a light source device according to the present disclosure. The embodiments are not intended to limit the present disclosure. Furthermore, explanation will be given, assigning identical reference symbols to identical parts throughout the drawings.

FIG.1is a diagram illustrating a schematic configuration of an endoscope system according to a first embodiment.FIG.2is a block diagram illustrating a schematic configuration of the endoscope system according to the first embodiment.

An endoscope system1illustrated inFIG.1andFIG.2includes an endoscope2that captures an in-vivo image of a subject by inserting a distal end portion into a body of the subject, a light source device3that generates illumination light emitted from a distal end of the endoscope2, a processing device4that subjects an image signal captured by the endoscope2to predetermined signal processing, and that performs an overall control of the operation of the entire endoscope system1, and a display device5that displays the in-vivo image generated by the signal processing of the processing device4.

The endoscope2includes a flexible long and thin insertion portion21, an operating unit22that is connected to a proximal end portion of the insertion portion21and that receives an input of various kinds of operation signals, and a universal cord23that extends in a direction different from a direction in which the insertion portion21extends from the operating unit22, and that has various kinds of cables connecting the light source device3and the processing device4inside.

The insertion portion21includes a distal end portion24that is equipped with two-dimensionally aligned imaging devices244that receive light and perform photoelectric conversion, to generate a signal, a bendable portion25that is constituted of plural bending pieces to be bendable, and a flexible tube26that is flexible and long-shaped, and that is connected to a proximal end portion of the bendable portion25. The insertion portion21is inserted into a body cavity of the subject, and images a subject, such as a living tissue, at a position at which outside light cannot reach by the imaging device244.

The distal end portion24includes a light guide241that is formed using a glass fiber or the like, and that forms a light guiding path for light emitted by the light source device3, an illumination lens242that is arranged at a distal end of the light guide241, an optical system243for light condensing, and the imaging device244(imaging unit) that is arranged at an image forming position of the optical system243, and that receives light condensed by the optical system243to convert into an electrical signal by performing photoelectric conversion, and that subjects it to predetermined signal processing.

The optical system243is constituted of one or more lenses, and has an optical zoom function that changes an angle of view, and a focus function that changes a focal point.

The imaging device244generates an electrical signal (image signal) by photoelectric-converting light from the optical system243. Specifically, the imaging device244includes a light receiving unit244ain which plural pixels each including a photodiode that accumulates an electric charge according to a light amount, a capacitor that converts an electric charge transferred from the photodiode into a voltage level, or the like are arranged in a matrix shape, and in which each pixel generates an electrical signal by photoelectric converting light from the optical system243, and a reading unit244bthat sequentially reads electrical signals generated by pixels that are arbitrarily configured to be read out of the plural pixels of the light receiving unit244a, to output as image signals. The imaging device244is implemented by using, for example, a charge coupled device (CCD) image sensor, or a complementary metal oxide semiconductor (CMOS) image sensor.

The endoscope2has a memory (not shown) that stores an execution program and a control program for the imaging device244to perform various kinds of operations, and data including identification information of the endoscope2. The identification information includes inherent information (ID) of the endoscope2, a model year, specification information, a transmission mode, and the like. Moreover, the memory may temporarily store image data generated by the imaging device244and the like.

The operating unit22includes a bending knob221that bends the bendable portion25in an up-and-down direction and a left-and-right direction, a treatment-tool inserting portion222to insert a treatment tool, such as biopsy forceps, an electrosurgical knife, and an inspection probe, into a body cavity of the subject, and plural switches223serving as an operation input unit that inputs an operation instruction signal for a peripheral devices, such as an air feeding means, a water feeding means, and a screen display control, in addition to the processing device4. The treatment tool inserted from the processing-tool inserting portion222is exposed out from an opening portion (not shown) through a treatment tool channel (not shown) of the distal end portion24.

The universal cord23has therein at least the light guide241and a bundled cable245in which one or more cables are bundled. The bundled cable245includes a signal wire to transmit an image signal, a signal wire to transmit a drive signal to drive the imaging device244, and a signal wire to communicate information including inherent information about the endoscope2(the imaging devices244), and the like. In the present embodiment, it will be explained such that an electrical signal is transmitted using the signal wire, but it may be used to transmit an optical signal, or may be used to transmit a signal between the endoscope2and the processing device4by wireless communication.

Subsequently, a configuration of the light source device3will be explained. The light source device3includes a light source unit31and an illumination control unit32.

The light source unit31is constituted of plural light sources that emit plural illumination lights having wavelength bands different from one another, plural lenses, and the like, and emits illumination light including light of a predetermined wavelength by driving of each light source. Specifically, the light source unit31includes a light source driver310, a first light-source group311B that emits light (blue illumination light) having a wavelength band of 390 nm to 495 nm, a second light-source group311G that emits light (green illumination light) having a wavelength band of 495 nm to 590 nm, a third light-source group311R (red illumination light) having a wavelength band of 590 nm to 750 nm, first lenses (first lenses312B,312G,312R) that respectively gather illumination lights emitted by the respective light sources, light amount sensors (light amount sensors313B,313G,313R) that respectively detect a light amount of illumination light that has passed through the first lens, second lenses (second lenses314B,314G,314R) that respectively gather illumination lights that have passed through the light amount sensors, a dichroic mirror315that bends light of a wavelength band emitted by the first light source group311B, and lets light of other wavelength bands pass through, a dichroic mirror316that bends light of a wavelength band emitted by the second light source group311G, and lets light of other wavelengths bands pass through, and a lens317that guides light of wavelengths emitted by the respective light sources to the light guide241. The respective light source groups are implemented by using plural semiconductor lasers, plural LED light sources, or the like. The dichroic mirrors315,316bend light from the light source groups to make them travel along the same optical axis.

Each of the light amount sensor has a diffuser arranged therein, and emits incident illumination light in a diffused manner. The light amount sensor acquires a part of light emitted by a light source before (or after) passing through the diffuser, and outputs its light amount value, or outputs an estimated value of a light amount of light that has been emitted by the light source based on the light amount value of the acquired light.

In the light sources, a cooling mechanism to cool down a heat generated at the time of driving is provided. The cooling mechanism is constituted of a Peltier device, heat sink, or the like.

The light source driver310causes the light sources to emit light by supplying an electric current to the respective light source groups under control of the illumination control unit32.

In the light source unit31, the first light source group311B, the second light source group311G, and the third light source group311R are controlled to emit illumination light in respective different timing, to emit illumination light of a single color to the outside, or controlled to emit light from all of the light sources, to emit illumination light of white color to the outside.

The illumination control unit32controls a power amount to be supplied to the respective light sources based on a control signal (light modulation signal) from the control unit44, and controls driving timing of the respective light sources.

Next, a configuration of the processing device4will be explained. The processing device4includes an image processing unit41, a synchronization-signal generating unit42, an input unit43, a control unit44, and a storage unit45.

The image processing unit41receives image data of illumination light of respective colors captured by the imaging device244from the endoscope2. When analog image data is received from the endoscope2, the image processing unit41performs A/D conversion, to generate a digital image signal. Moreover, when image data is received as an optical signal from the endoscope2, the image processing unit41performs photoelectric conversion, to generate digital image data.

The image processing unit41subjects image data received from the endoscope2to predetermined image processing to generate an image, and outputs it to the display device5. The predetermined processing includes synchronization processing, tone correction processing, color correction processing, and the like. The synchronization processing is processing of synchronizing respective pieces of R image data based on image data generated by the imaging device244at the time of irradiation of R illumination light by the light source unit31, G image data based on image data generated by the imaging device244at the time of irradiation of G illumination light by the light source unit31, and B image data based on image data generated by the imaging device244at the time of irradiation of B illumination by the light source unit31. The tone correction processing is processing of performing correction of tones with respect to the image data. The color correction processing is processing of performing color correction with respect to the image data. The image processing unit41generates a processed image signal including an in-vivo image that has been generated by the image processing described above (hereinafter, simply referred to as image signal also). The image processing unit41may perform gain adjustment according to the brightness of an image. The image processing unit41is constituted of a general-purpose processor, such as a central processing unit (CPU), or a dedicated purpose processor including various kinds of arithmetic circuits that perform specific functions, such as an application specific integrated circuit (ASIC).

Moreover, the image processing unit41may have a configuration including a frame memory that holds the R image data, the G image data, and the B image data.

The synchronization-signal generating unit42generates a clock signal (synchronization signal) to be a reference for operations of the processing device4, and outputs the generated synchronization signal to the light source device3, the image processing unit41, the control unit44, and the endoscope2. The synchronization signal generated by the synchronization-signal generating unit42includes a horizontal synchronization signal and a vertical synchronization signal.

Therefore, the light source device3, the image processing unit41, the control unit44, and the endoscope2operate in synchronization with one another based on the generated synchronization signal.

The input unit43is implemented by using a keyboard, a mouse, a switch, and a touch panel, and receives an input of various kinds of signals, such as an operation instruction signal that instructs an operation of the endoscope system1, and the like. The input unit43may include a switch provided in the operating unit22, or a portable terminal, such as an external tablet type computer.

The control unit44performs drive control of the respective components including the imaging device244and the light source device3, and input/output control of information with respect to the respective components. The control unit44refers to control information data (for example, read out timing) for imaging control stored in the storage unit45, and transmits it as a drive signal to the imaging device244through a predetermined signal wire included in the bundled cable245. The control unit44is constituted of a general purpose processor, such as a CPU, or a dedicated purpose processor including various kinds of arithmetic circuits that perform specific functions, such as an ASIC.

The storage unit45stores various kinds of programs to operate the endoscope system1, and data including various kinds of parameters necessary for the operation of the endoscope system1. Moreover, the storage unit45stores identification information of the processing device4. The identification information includes inherent information (ID) of the processing device4, a model year, specification information, and the like. Moreover, the storage unit45includes an illumination-information storage unit451that stores information about arrangement of the light sources included in the light source device3, and the like. The illumination-information storage unit451stores, for example, light emitting order of the light sources according to a set light amount (a light amount of illumination light emitted by the light source device3in this case).

Furthermore, the storage unit45stores various kinds of programs including an image-acquisition processing program to perform an image-acquisition processing method of the processing device4. The various kinds of programs can be stored in a computer-readable recording medium, such as a hard disk, a flash memory, a compact disk read-only memory (CD-ROM), a digital versatile disk read-only memory (DVD-ROM), and a flexible disk, to be widely distributed. Note that the various kinds of programs described above can also be acquired by downloading through a communication network. The communication network herein is implemented by, for example, an existing public line network, a local area network (LAN), a wide area network (WAN), or the like, and may be of either wired or wireless communication.

The storage unit45having the configuration as described above is implemented by using a ROM in which the various kinds of programs are installed in advance, a random access memory (RAM), a hard disk, or the like that stores arithmetic parameters and data of respective processing.

The display device5displays a display image corresponding to an image signal received from the processing device4(image processing unit41) through a video cable. The display device5is constituted of a monitor of a liquid crystal, an organic electro luminescence (EL), or the like.

Subsequently, a configuration of the light source included in the light source device3will be explained, referring toFIG.3.FIG.3is a diagram for explaining an arrangement of the light sources of the light source device included in the endoscope system according to the first embodiment. In each of the light source groups, plural light sources are provided in the same arrangement. Hereinafter, the arrangement of the light sources of the first light-source group311B will be explained, referring toFIG.3. In the second light-source group311G and the third light-source group311R also, the light sources are arranged in the similar manner.

The first light-source group311B includes a first light source331(first light emitter) constituted of a single light source, and a second light source332to a fifth light source335that are constituted of two light sources as one set. The second light source332to the fifth light source335are arranged coaxially about the first light source331. The second light source332to the fifth light source335respectively correspond to partial light emitters, and constitutes a second light emitter as a whole. Light emitted from the first light source331corresponds to first light. Moreover, light emitted from the second light source332to the fifth light source335corresponds to second light. The second light is constituted of light emitted from at least one light source out of the second light source332to the fifth light source335, and it can be light emitted from a single light source (for example, the second light source332only), and can be combined light of light respectively emitted from multiple light sources (for example, all of the second light source332to the fifth light source335).

The first light source331is constituted of a semiconductor laser. The first light source331has a maximum light emitting amount smaller than a maximum light emitting amount of the second light source332to the fifth light source335, and functions as a light source of fine adjustment.

The second light source332includes two light sources (light sources332A,332B) constituted of a semiconductor laser. The light sources332A,332B are respectively arranged on a straight line passing through the first light source331. This straight line is a straight line that extends in a direction of diameter of a circle having the first light source331in the center. InFIG.3, the light sources332A,332B are arranged sequentially in order of the light sources332A,332B from the first light source331side.

The third light source333includes two light sources (light sources333A,333B) that are constituted of a semiconductor laser. The light sources333A,333B are respectively arranged on a straight line passing through the first light source331. This straight line is a straight line that extends in a direction of diameter of a circle having the first light source331in the center, and is a straight line perpendicular to the straight line on which the second light source332is arranged. InFIG.3, the light sources333A,333B are arranged sequentially in order of the light sources333A,333B from the first light source331side.

The fourth light source334includes two light sources (light sources334A,334B) that are constituted of a semiconductor laser. The light sources334A,334B are respectively arranged on a straight line passing through the first light source331. This straight line is a straight line that extends in a direction of diameter of a circle having the first light source331in the center, and is a straight line passing through the second light source332. In other words, the fourth light source334is arranged on the opposite side to the second light source332relative to the first light source331. InFIG.3, the light sources334A,334B are arranged sequentially in order of the light sources333A,333B from the first light source331side.

The fifth light source335includes two light sources (light sources335A,335B) that are constituted of a semiconductor laser. The light sources335A,335B are respectively arranged on a straight line passing through the first light source331. This straight line is a straight line that extends in a direction of diameter of a circle having the first light source331in the center, and is a straight line passing through the third light source333. In other words, the fifth light source335is arranged on the opposite side to the third light source333relative to the first light source331. InFIG.3, the light sources335A,335B are arranged sequentially in order of the light sources335A,335B from the first light source331side.

In the first light source group311B, the light sources332A,333A,334A,335A are arranged coaxially, and the light sources332B,333B,334B,335B are arranged coaxially.

Moreover, in the first light source group311B, the light modulation resolution of the first light source331is higher than the light modulation resolution of the second light source332to the fifth light source335. Conversely, because the second light source332to the fifth light source335have the configuration in which two light sources are lit simultaneously, the light modulation resolution of the second light source332to the fifth light source335is lower than the light modulation resolution of the first light source331. The light modulation resolution signifies the brightness when intervals of light modulation value in a control circuit is the same, and the resolution is higher when the brightness is lower. The first light source331has smaller adjustment width is smaller than that of the second light source332to the fifth light source335, and fine adjustment is possible.

The illumination control unit32turns on and off the respective light sources in order set in advance. In the first embodiment, the illumination control unit32turns on the first light source331, the second light source332, the third light source333, the fourth light source334, and the fifth light source335sequentially in this order, and turns off the fifth light source335, the fourth light source334, the third light source333, the second light source332, and the first light source331sequentially in this order. The illumination control unit32turns off the light sources in inverse order to the light-on order. Note that there is a case in which a light source in a later stage is not turned on depending on a set light amount.

FIGS.4A-4Eare diagrams for explaining the light-on order of the light sources of the light source device included in the endoscope system according to the first embodiment.FIGS.4A-4Eillustrate a case in which all of the light sources are turned on. InFIGS.4A-4E, an uncolored (not hatched) circle (light source) indicates a light-on state, and a hatched circle indicates a light-off state. Under control of the illumination control unit32, first, the first light source331is turned on (refer toFIG.4A). Subsequently, the second light source332is turned on (refer toFIG.4). Next, the third light source333is turned on (refer toFIG.4C), and then the fourth light source334is turned on (refer toFIG.4D). Finally, the fifth light source335is turned on (refer toFIG.4E). Subsequently, the second light source332is turned on (refer to (b) inFIG.4). Next, the third light source333is turned on (refer to (c) inFIG.4), and then the fourth light source334is turned on (refer to (d) inFIG.4). Finally, the fifth light source335is turned on (refer to (e) inFIG.4).

FIGS.5A-5Fare diagrams for explaining light-off order of the light sources of the light source device included in the endoscope system according to the first embodiment.FIGS.5A-5Fillustrate the light-off order when all of the light sources are turned on in the order illustrated inFIGS.4A-4E. InFIGS.5A-5F, similarly toFIGS.4A-4E, an uncolored circle indicates a light-on state, and a hatched circle indicates a light-off state. Under control of the illumination control unit32, first, the fifth light source335is turned off (refer toFIG.5B) from the state in which all of the light sources are turned on (refer toFIG.5A). Subsequently, the fourth light source334is turned off (refer toFIG.5C). Next, the third light source333is turned off (refer toFIG.5D), and thereafter, the second light source332is turned off (refer toFIG.5E). Finally, the first light source331is turned off (refer toFIG.5F).

In the first embodiment explained above, in a configuration in which eight light sources coaxially arranged, and one light source arranged in the center thereof are provided, and illumination light of one color component is emitted, the eight light sources are divided into four groups, and lighting is controlled according to a set light amount. According to the first embodiment, because the light source to be turned on is fixed to the first light source331, it is possible to control a light amount of the illumination light while suppressing variations of light properties of the illumination light in a dark scene. Moreover, according to the first embodiment, the respective light sources in the second light source332to the fifth light source335are controlled collectively, control units can be reduced, and consequently, an increase in size of a circuit scale for light sources can be suppressed in a configuration including plural light sources.

Next, a second embodiment of the present disclosure will be explained, referring toFIG.6. An endoscope system according to the second embodiment has the same configuration as that of the first embodiment, except that an arrangement of the light sources in the light source device1of the endoscope system1described above is changed. Hereinafter, the arrangement of the light sources different from the configuration of the first embodiment, and the illumination control therewith will be explained.FIG.6is a diagram for explaining an arrangement of light sources of a light source device included in the endoscope system according to the second embodiment. Hereinafter, an arrangement of the light sources in the first light source group311B will be explained, referring toFIG.6. Similarly to the first embodiment, in the second light source group311G and the third light source group311R also, the light sources are arranged in the similar manner.

The first light source group311B according to the second embodiment includes a first light source336(the first light emitter) constituted of two light sources as a set, and the second light sources332to the fifth light sources335that are constituted of two light sources as a set. The second light source332to the fifth light source335are coaxially arranged having the first light source336in the center. Hereinafter, the first light source336having the configuration different from the first embodiment will be explained.

The first light source336has two light sources (light sources336A,336B) constituted of a semiconductor laser. In the first light source336, only one light source out of the light sources336A,336B is turned on. In the first light source336, the first light is emitted from the light source336A or the light source336B. Therefore, the first light source336has a maximum light emitting amount smaller than a maximum light emitting amount of the second light source332to the fifth light source335, and functions as a light source of fine adjustment.

The light sources336A,336B are respectively arranged on a straight line that passes through the center of a circuit on which the second light source332to the fifth light source335are arranged, and on which the third light source333and the fifth light source335are arranged. The light sources336A,336B may be arranged on a straight line on which the second light source332and the fourth light source334are arranged, or may be arranged on a straight line that is different from the straight line on which the second light source332to the fifth light source335are arranged.

In the first light source group311B, because only one out of the two light sources (the light sources336A,336B) is turned on, the light modulation resolution of the first light source336is higher than the light modulation resolution of the second light source332to the fifth light source335.

The illumination control unit32turns on and off the respective light sources in order set in advance. Specifically, the illumination control unit32turns on and off the light sources according to either mode out of two light-on modes. For example, in a first light-on mode, the light source336A, the second light source332, the third light source333, the fourth light source334, the fifth light source335are sequentially turned on in this order, and the fifth light source335, the fourth light source334, the third light source333, the second light source332, and the light source336A are sequentially turned off in this order.

FIGS.7A-7Eare diagrams for explaining light-on order of the light sources in the first light-on mode of the light source device included in the endoscope system according to the second embodiment.FIGS.7A-7Eillustrate a case in which all of the light sources are turned on. Hereinafter, an uncolored circle indicates a light-on state, and a hatched circle indicates a light-off state. Under control of the illumination control unit32, first, the light source336A of the first light source336is turned on (refer toFIG.7A). Subsequently, the second light source332is turned on (refer toFIG.7B). Next, the third light source333is turned on (refer toFIG.7C), and thereafter, the fourth light source334is turned on (refer toFIG.7D). Finally, the fifth light source335is turned on (refer toFIG.7E). In the first light-on mode, the light source336B of the first light source336is not turned on.

FIGS.8A-8Fare diagrams for explaining light-off order of the light sources in the first light-on mode of the light source device included in the endoscope system according to the second embodiment.FIGS.8A-8Fillustrate the light-off order when all of the light sources are turned on in the order illustrated inFIGS.7A-7E. Under control of the illumination control unit32, first, the fifth light source335is turned off (refer toFIG.8B) from the state in which all of the light sources are turned on (refer toFIG.8A) in the light-on order illustrated inFIGS.7A-7E. Subsequently, the fourth light source334is turned off (refer toFIG.8C). Next, the third light source333is turned off (refer toFIG.8D), and thereafter, the second light source332is turned off (refer toFIG.8E). Finally, the light source336A is turned off (refer toFIG.8F).

On the other hand, in the second light-on mode, the light source336B, the fifth light source335, the fourth light source334, the third light source333, and the second light source332are sequentially turned on in this order, and the second light source332, the third light source333, the fourth light source334, the fifth light source335, and the light source336B are sequentially turned off in this order. Note that there is a case in which a light source in a later stage is not turned on depending on a set light amount.

FIGS.9A-9Eare diagrams for explaining light-on order of the light sources in a second light-on mode of the light source device included in the endoscope system according to the second embodiment.FIGS.9A-9Eillustrate a case in which all of the light sources are turned on. Under control of the illumination control unit32, first, the light source336B of the first light source336is turned on (refer toFIG.9A). Subsequently, the fifth light source335is turned on (refer toFIG.9B). Next, the fourth light source334is turned on (refer toFIG.9C), and thereafter, the third light source333is turned on (refer toFIG.9D). Finally, the second light source332is turned on (refer toFIG.9E). In the second light-on mode, the light source336A of the first light source336is not turned on.

FIGS.10A-10Fare diagrams for explaining light-off order of the light sources in the second light-on mode of the light source device included in the endoscope system according to the second embodiment.FIGS.10A-10Fillustrate the light-off order when all of the light sources are turned on in the light-on order illustrated inFIGS.9A-9E. Under control of the illumination control unit32, the second light source332is turned off (refer toFIG.10B) from the state in which all of the light sources are turned on (refer toFIG.10A) in the light-on order illustrated inFIGS.9A-9E. Subsequently, the third light source333is turned off (refer toFIG.10C). Next, the fourth light source334is turned off (refer toFIG.10D), and thereafter, the fifth light source335is turned off (refer toFIG.10E). Finally, the light source336B is turned off (refer toFIG.10F).

When the light sources are continuously lit in the first light-on mode, the utilization rate of the second light source332to the fifth light source335decreases in order of the second light source332, the third light source333, the fourth light source334, and the fifth light source335. For example, setting the utilization rate of the first light source336(the light source336A or the light source336B) to 100%, it is assumed that the utilization rate of the second light source332is 80%, the utilization rate of the third light source333is 60%, the utilization rate of the fourth light source is 40%, and the utilization rate of the fifth light source335is 20% when the first light source336to the fifth light source335are turned on and off in uniform timing. In this case, grouping the second light source332of the highest utilization rate and the fifth light source335of the lowest utilization rate into a set, and grouping the third light source333and the fourth light source334of the intermediate utilization rate into a set, in the second light-on mode, the light-on order is switched from the first light-on mode in each set. By appropriately switching the second light-on mode with switched light-on order and the first light-on mode, the utilization rate of the light sources in each set can be equalized. Consequently, the utilization rate (light-on time) of the second light source332to the fifth light source335can be equalized.

The first and the second light-on modes can be switched under control of the control unit44, and time required for the illumination control, either one of the number of days of operation, and the life of the light source336A (or the light source336B) can be the trigger. Conditions to perform the switching control are stored in the illumination-information storage unit451in advance.

In the second embodiment explained above, in a configuration in which eight light sources coaxially arranged, and one light source arranged in the center thereof are provided similarly to the first embodiment, and illumination light of one color component is emitted, the eight light sources are divided into four groups, and lighting is controlled according to a set light amount. According to the second embodiment, because the light source to be turned on first is fixed to the first light source336, it is possible to control a light amount of the illumination light while suppressing variations of light properties of the illumination light in a dark scene. Moreover, according to the second embodiment, the respective light sources in the second light source332to the fifth light source335are controlled collectively, control units can be reduced, and consequently, an increase in size of a circuit scale can be suppressed.

Moreover, in the second embodiment, two pieces of the light sources are provided in the first light source336, and the light source to be turned on is switched in predetermined timing, and the light-on order of the light sources grouped into a set according to the maximum utilization rate (in this example, the second light source332and the fifth light source335, the third light source333and the fourth light source334) is switched. By the switching of the light-on mode described above, the life of the light sources as a whole in the light source device can be increased.

Furthermore, in the second embodiment, because it is configured to control the light-on order, grouping the light sources of the highest and the lowest utilization rates into a set, the light-on control of the light sources in which a difference in the utilization rate among the light sources is minimized is performed, and the life of the light sources can be increased.

The grouping of the light sources may be determined by using a randomly extracted function (random number) each time of operation. Also when the grouping is determined randomly, the utilization rates are equalized as the number of operation increases.

In the second embodiment described above, it has been explained that light is emitted only from one of the light sources (the light source336A or the light source336B) of the first light source336in the first light source group311B, but light may be emitted from both the light source336A and the light source336B. In this case, for example, light emitted from each light source is ½ each of an amount of light emitted as the first light source336.

Furthermore, in the second embodiment described above, the life of the light sources are increased by grouping the light sources according to the utilization rate in the first light-on mode and switching the light-on order, but the precedence of the light sources to be turned on may be rotated. For example, a light-on order in which the second light source332is given first priority to be turned on, a light-on order in which the third light source333is given first priority to be turned on, a light-on order in which the fourth light source334is given first priority to be turned on, and a light-on order in which the fifth light source335is given first priority to be turned on are rotated. Switching of the light sources to be prioritized is performed on the conditions explained in the second embodiment described above.

Moreover, in the second embodiment described above, light (the first light) may be emitted from both of the light sources336A and336B simultaneously. In this case, the first light source336and the second light source332to the fifth light source335have the same light modulation resolution. Also in this case, because the light source to be turned on first is fixed to the first light source336, and the 10 pieces of the light sources are controlled in a set of two pieces, control units can be reduced, while suppressing variations of light properties of the illumination light in a dark scene. Furthermore, if light of a desired light amount can be emitted, the number of light sources in each of the first light source336and the second light source332to the fifth light source335can be one.

Moreover, although it has been explained in the first and the second embodiments described above that the first light source group311B has the first light source331(or336) and four pieces of light sources (the second light source332to the fifth light source335) arranged therearound, for example, as long as having the maximum light emitting amount larger than that of the first light source, and having the light modulation resolution lower than that of the first light source, the light source (the first light emitter) to be provided around the first light source (the second light emitter) may be one piece. Moreover, although it has been explained that the second light source332to the fifth light source335have two pieces of light sources, they may be configured to have one piece of light source, or three or more pieces of light sources. Furthermore, as long as light can be supplied to the light guide, the arrangement of the first light source to the fifth light source is not limited to the arrangement illustrated inFIGS.3and4described above.

Moreover, although it has been explained in the first and the second embodiment described above that the light source device3is configured to be a separate unit from the endoscope2, for example, a configuration in which the light source device is arranged in the endoscope2, such that the semiconductor laser is arranged at a distal end of the endoscope2, may be applied also. Furthermore, the function of the processing device4may be added to the endoscope2.

Moreover, although it has been explained in the first and the second embodiments described above that the light source device3is a separate unit from the processing devices4,3A, the light source device3and the processing device4may be unified in one unit, and for example, the light source unit31and the illumination control unit32may be provided in the processing device4.

Furthermore, in the first and the second embodiments, the light source device3may be constituted of an LED light source instead of the semiconductor laser, or may be configured to include a white light source (for example, a xenon lamp or a halogen lamp) and a revolving filter having three transmission filters that pass a wavelength band of red, a wavelength band of green, and a wavelength band of blue, respectively on an optical path of illumination light to be emitted by the white light source, and to irradiate illumination light including respective wavelength bands of red, green, and blue by revolving the revolving filter.

Moreover, although it has been explained in the first and the second embodiments described above that the endoscope system according to the present disclosure is the endoscope system1using the flexible endoscope2, a subject of observation of which is a living tissue inside a body of a subject and the like, it can be applied also to a rigid endoscope, an endoscope system for an industrial use to observe properties of a material, a capsule endoscope, a fiberscope, and an endoscope system in which a camera head is attached to an eyepiece of an optical endoscope, such as an optical borescope.