A slit-lamp microscope includes an illumination system that is configured to project a slit light onto a subject eye; a slit portion that is configured to generate the slit light having a width by passing a light from a light source through a slit between a pair of slit blades in the illumination system; and a controller that is configured to control the light source, wherein the controller is configured to turn the light source off when the pair of slit blades is closed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2023-056403 filed with the Japan Patent Office on Mar. 30, 2023, the entire disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present disclosure relates to a slit-lamp microscope.

BACKGROUND

Conventionally, there has been a slit-lamp microscope that includes an illumination system for irradiating a subject eye with a slit light and an observation system for observing the subject eye. In this slit-lamp microscope, the illumination system is provided with a slit portion that makes a slit light with any width by passing the light from a light source between a pair of slit blades (see JP6904776B2).

This conventional slit-lamp microscope is capable of providing a condition in which a space or slit the pair of slit blades is closed to block the light from the light source, thereby not irradiating the subject eye with the slit light. However, in the slit-lamp microscope, even if the pair of slit blades are in contact with each other, a gap may be formed therebetween unless the processing accuracy in producing both slit blades is extremely high, such that the light passes through the gap and then reaches the subject eye. With this, in the slit-lamp microscope, the gap formed between the two slit blades may be recognized by the examinee or examiner, thereby giving him/her an impression of the slit-lamp microscope having a low quality.

The present disclosure has been made by considering the above problem. An object of the present disclosure is to provide a slit-lamp microscope that is capable of preventing the light from escaping or streaming through a gap between the two slit blades when the slit has been closed.

SUMMARY

To achieve the object, a slit-lamp microscope includes an illumination system that is configured to project a slit light onto a subject eye; a slit portion that is configured to generate the slit light having a width by passing light from a light source through a slit between a pair of slit blades in the illumination system; and a controller that is configured to control the light source, wherein the controller is configured to turn the light source off when the pair of slit blades is closed.

DESCRIPTION OF EMBODIMENTS

A slit-lamp microscope according to an embodiment of the present disclosure will be described below with reference toFIGS.1to8.

The slit-lamp microscope10according to the first embodiment is described with headings “Overall Configuration”, “Detailed Configuration of Illumination System”, “Detailed Configuration of Observation System”, and “Detailed Configuration of Background Illumination Unit”, as follows. The slit-lamp microscope10is used as an ophthalmologic apparatus that is configured to acquire cross-sectional cornea images by optically cutting out a thin slice of the cornea of the subject eye E with a slit light.

(Overall Configuration) As shown inFIG.1, the slit-lamp microscope10includes a microscope body11, an illumination system12, an observation system13, a background illumination unit20, and a controller30. The microscope body11is installed on a table1and supports the illumination system12, the observation system13, and the background illumination unit20. The microscope body11includes a pedestal11afixed to the top surface of the table1, a base14provided on the top surface of the pedestal11a, a support15provided on the top surface of the base14, and a chin rest16supported on the pedestal11a. The base14is provided relative to the pedestal11ato be movable in frontward and rearward directions and leftward and rightward directions as viewed from the subject eye E through a movement mechanism14a. The base14is moved by tilting an operation handle14b. The support15on the top surface of the base14is moved in vertical directions by rotating the operation handle14baround its axis.

The support15includes a pedestal15a, a first support arm15b, and a second support arm15c. The pedestal15ais provided on the top surface of the base14, and the first support arm15band the second support arm15cextend upward from the pedestal15a. Herein, each of the first support arm15band the second support arm15care independently rotatable around a coaxial vertical axis.

The first support arm15bincludes an upper part to which an illumination system housing12ais attached to support the illumination system12. The illumination system housing12aaccommodates the illumination system12therein. The first support arm15bis manually rotatable, and the rotation of the first support arm15brotates the illumination system housing12aaround the subject eye E. With this, it is possible to change the slit-light projection direction relative to the subject eye E. The first support arm15bmay be configured to rotate upward or downward. By having such a configuration, the first support arm15bcan change the elevation angle or depression angle of the slit light to the subject eye E. The second support arm15cincludes an upper part to which an observation system housing13ais attached to support the observation system13. The observation system housing13aaccommodates the observation system13therein. The second support arm15cis rotatable, and the rotation of the second support arm15crotates the observation system housing13aaround the first support arm15b. With this, it is possible to change the observation direction of the observation system13relative to the subject eye E.

The first and second support arms15b,15cmay be configured to electrically and automatically be rotatable, respectively. In this case, it is necessary to provide an arm drive mechanism including an actuator that generates a drive force to rotate the first and second support arms15b,15c, and a transmission mechanism to transmit the drive force. As the actuator, a motor such as a stepping motor (pulse motor) may be used, for example. As the transmission mechanism, a combination of gearwheels, rack and pinion, or the like may be used, for example.

The chin rest16is disposed at a position in front of the observation system housing13a. The chin rest16includes a chin rest portion16aand a forehead rest portion16bfor stabilizing the face (head) of the examinee. In the slit-lamp microscope10, the examiner observes the subject eye E in a condition that the examinee facing the table1placed his/her face (i.e., chin and forehead) on the chin rest portion16aand the forehead rest portion16b.

The illumination system12projects the slit light towards the subject eye E. The illumination system12is accommodated in the illumination system housing12a. The intensity of the slit light can be changed by operating a brightness adjustment knob14cprovided on the base14. The slit light refers to an illumination light for observing the cornea or fundus of the subject eye E, and the illumination light has an illumination region which has been formed into a band shape by blocking a part of the illumination region. Below the illumination system housing12a, a mirror12bis disposed which reflects the slit light projected from the illumination system12towards the subject eye E. The mirror12bis attached to the first support arm15b. The mirror12balso makes it possible to reflect the background light projected from the background illumination unit20toward the subject eye E.

The observation system13observes and photographs or images the reflection light reflected by the subject eye E. Herein, the reflection light includes not only the slit light and the background light reflected by the subject eye E but also various lights such as scattered light from the subject eye E and its surroundings. In the first embodiment, these various lights are correctively referred to as “the reflection light”. The observation system13is accommodated in the observation system housing13a. At a terminal end of the observation system housing13a, an eyepiece portion13bis provided. The examiner observes the subject eye E with the naked eyes by looking through the eyepiece portion13b. On a side surface of the observation system housing13a, an observation magnification operation knob13cis disposed for changing the observation magnification.

An imaging device13dfor photographing or imaging the subject eye E is detachably connected to the observation system housing13a. The imaging device13dincludes an image sensor13e. The image sensor13eis a photoelectric conversion element to detect light and output electric signals (image signals). The image sensor13eoutputs image signals to the controller30. For the image sensor13e, for example, a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal Oxide Semiconductor) image sensor is used.

The background illumination unit20illuminates by the background light a surrounding region of a projection region of the slit light from the illumination system12to the subject eye E. It is sufficient that the projection region by the background illumination unit20includes at least this surrounding region and it may partly overlap with the projection region by the illumination system12.

The controller30is connected to the slit-lamp microscope10(microscope body11). The controller30controls each part of the slit-lamp microscope10and conducts various control processes and calculations. The controller30is built in the base14in the first embodiment but may be accommodated in the microscope body11or the like. Furthermore, the controller30may be arranged to be separate from the microscope body11and is not limited to the configuration of the first embodiment.

(Detailed Configuration of Illumination System) As shown inFIG.2, the illumination system12includes, on an illumination optical axis O1, a light source121, a relay lens122, an illumination diaphragm123, a condensing lens124, a slit portion125, a field diaphragm126, and an imaging lens127. The light source121is a light source of the slit light for observing the cornea and fundus of the subject eye E. The light source121is configured to output at least visible light. The first embodiment uses both a light source (halogen lamp, LED (Light Emitting Diode), or the like) that outputs stationary or continuous light, and a light source (xenon lamp, LED, or the like) that outputs flashlight. The illumination system12may be configured by a single light source or a plurality of light sources. In the illumination system12, a plurality of monochromatic light sources may be provided separately, such as in the case where a light source for observing the cornea and a light source for observing the fundus are provided separately. The light source121is capable of changing the luminous intensity (amount of light) in accordance with the magnitude of the applied power under the control of the main controller31, which is described below.

The illumination diaphragm123blocks a peripheral part of the illumination light and transmits only a central part of the illumination light. The illumination diaphragm123is capable of changing the size (diameter and aperture area) of its light-transmitting part, thereby adjusting the illuminance of an illuminated part. The illumination diaphragm123is capable of reducing the reflection of the illumination light by cornea Ec and/or crystalline lens of the subject eye E and adjusting the brightness of the illumination light. The illumination diaphragm123according to the first embodiment includes a diaphragm knob123aprovided on the illumination system housing12a(seeFIG.1). The diaphragm knob123ais linked by a link mechanism to a diaphragm frame portion, which forms the light-transmitting part, and is configured to change the size of the light-transmitting part according to a rotational operation on itself. The diaphragm knob123amay be configured to be freely adjustable by a manual operation with another configuration or to perform an electric adjustment under the control of the main controller31.

The slit portion125is used for generating the slit light. The slit portion125includes a pair of slit blades125a,125bthat are opposed to each other with a predetermined distance therebetween (seeFIGS.2and3). The slit portion125is capable of moving the pair of slit blades125a,125bto adjust the distance d (slit width) between the slit blades125a,125bto any size (slit width). The slit portion125according to the first embodiment includes a slit opening/closing knob125cprovided at a lower part of the first support arm15b(seeFIG.1).

The slit opening/closing knob125cis linked to the pair of slit blades125a,125bby a link mechanism, and a rotational operation to the slit opening/closing knob125cis transmitted such that the two slit blades125a,125bare moved in an approaching direction or a separating direction relative to each other. Therefore, in the slit portion125, the two slit blades125a,125bapproach or separate from each other by the rotational operation to the slit opening/closing knob125caccording to the rotational direction of the slit opening/closing knob125cto have any distance d therebetween. Therefore, the slit portion125can change the width of the slit light in accordance with the rotational operation of the slit opening/closing knob125c. The slit portion125may be configured to freely adjust the distance d between the slit blades125a,125bby a manual operation with another configuration or to perform an electric adjustment under the control of the main controller31.

The slit opening/closing knob125caccording to the first embodiment makes it possible to conduct a rotational operation from a fully opened rotational position at which the distance d becomes maximum to a fully closed rotational position at which the distance d becomes minimum. In the slit opening/closing knob125c, when the rotation resistance (force resisting the rotation) against the rotational operation is at the fully closed rotational position, this position is different from those at other positions. Therefore, in the slit opening/closing knob125c, the force required for the rotational operation becomes larger as the rotation resistance increases, and the force required for the rotational operation becomes smaller as the rotation resistance decreases. Thereby, in the slit opening/closing knob125c, it is possible to recognize the fully closed rotational position by the feeling or sensation of the hand during the rotational operation, that is, the pair of slit blades125a,125bhas moved to the fully closed position. The change of the rotational resistance against the rotational operation is made possible by an exemplary configuration that a projection in the form of a plate spring is formed on one of the slit opening/closing knob125cand the first support arm15b(or its support portion) on which the knob125cis rotatably supported, and a recess for receiving the projection is formed on the other of them, thereby making the projection fitted into the recess at the fully closed rotational position. In such a configuration, it is possible to obtain a so-called click sensation at the fully closed rotational position. Therefore, the examiner can conduct the rotational operation without an unpleasant feeling and can recognize the fully closed rotational position by only the click sensation. As long as it can recognize the fully closed rotational position by the feeling in the hand or sensation, the change of the rotational resistance against the rotational operation may be achieved by another configuration, and it is not limited to the configuration of the first embodiment.

The illumination system12has a luminous flux control portion128that is capable of changing the area of an aperture128athat allows a luminous flux from the light source121to pass therethrough. The luminous flux control portion128limits the illumination range on the subject eye E by blocking a part of the luminous flux from the light source121.

The illumination system12has a filter portion129. The filter portion129is configured to select any filter F and to insert (dispose) it into or remove it from an optical path. The filter F consists of an optical element that removes or weakens a specific component of the illumination light. The filter F is, for example, a fluorescent filter (a filter (blue filter) that particularly transmits a wavelength component corresponding to blue color) used for improving contrast in a fluorescent observation of the subject eye E. As the filter F, it is possible to use, for example, a red-free filter (green filter) that makes it easy to observe blood vessels, a light-reducing filter (ND filter) that lowers the light quantity without changing color, or the like.

The filter portion129according to the first embodiment has a filter switch lever129ainstalled on the illumination system housing12ato insert the selected filter F (a fluorescent filter, red-free filter, light-reducing filter, etc.) into and remove it from the optical path of the illumination system12. The filter switch lever129ais linked to each filter F (its support frame) through a link mechanism and inserts any filter F into the optical path in accordance with the position of a slide operation conducted on itself. As long as the filter portion129can insert any filter F into and remove it from the optical path, such operation may be manually conducted by another configuration or electrically conducted under the control of the main controller31, which will be described later.

(Detailed Configuration of Observation System) The observation system13includes a pair of left and right optical systems. The examiner can observe the subject eye E with both eyes with the left and right optical systems of the observation system13. The symbol Ec denotes the cornea of the subject eye E, the symbol Ep denotes the iris, and the symbol Er indicates the fundus. The symbol Eo denotes the examiner's eye. In the observation system13, the left and right optical systems have generally similar configurations. Therefore, in the description below andFIG.2, only one of them will be described. As shown inFIG.2, each optical system of the observation system13includes an objective lens131, a magnification optical system132, a diaphragm133, a beam splitter134, an imaging lens135, a prism unit136, and an eyepiece lens137, which are provided on the observation optical axis O2. The beam splitter134may be provided in only one of the left and right optical systems or both of them.

The eyepiece lens137is provided in the eyepiece portion13b. In the observation system13, an image of an observation part is formed on an imaging position P by the imaging lens135. The examiner (examiner's eye Eo) observes the image on the imaging position P through the eyepiece lens137.

The magnification optical system132changes the magnification (angle of view) of observation images and photographed images of the subject eye E, which are taken by the eyepiece lens137. The magnification optical system132consists of a plurality of magnifying lens groups that may be selectively inserted with respect to the observation optical axis O2. Each of the magnifying lens groups includes a plurality (two inFIG.2) of magnifying lenses132a,132b, and the magnifying lens groups provide different magnifications, respectively. In the magnification optical system132, a desired magnification is set by a plurality of lenses of one magnifying lens group, which are arranged on the observation optical axis O2. In this magnification optical system132, the change of magnification, that is, the replacement of the magnifying lens group to be arranged on the observation optical axis O2can be conducted by operating the observation magnification operation knob13c. In the magnification optical system132, the magnification change (replacement of the magnifying lens group) may be electrically conducted by using a switch, etc. (not shown in the drawings) under the control of the after-mentioned main controller31.

The beam splitter134divides the light traveling along the observation optical axis O2into two. The light penetrated the beam splitter134is guided to the subject eye Eo via the imaging lens135, the prism unit136, and the eyepiece lens137. The prism unit136includes two optical elements136a,136bto invert the image and change the width between the left and right observation optical axes O2to correspond to the width of the examiner's eyes. Meanwhile, the light reflected by the beam splitter134is guided to the image sensor13eof the imaging device13dvia an imaging lens138and a mirror139. The image sensor13edetects this reflected light and generates image signals.

(Detailed Configuration of Background Illumination Unit) The background illumination unit20illuminates the background of the observation image in the observation system13. As shown inFIG.4, the background illumination unit20according to the first embodiment is formed separate from the microscope body11and can be attached to any position (e.g., to the illumination system housing12ain the example shown inFIG.4) of the microscope body11. As its attachment means, it is possible to use a magnet, a suction cup, an adhesive sheet, a hook and loop fastener, etc. alone or in combination. It is optional to provide a configuration in which the microscope body11(illumination system housing12a) is provided with a holder to hold the background illumination unit20(the after-mentioned unit case21), thereby attaching the background illumination unit20to the microscope body11.

As shown inFIG.5, the background illumination unit20includes a unit case21, a background light source22, a battery23, a background light controller24, and a background light operation device25. By attaching the background illumination unit20to the illumination system housing12a, a background illumination optical axis O3from the background light source22is merged with the illumination optical axis O1(observation optical axis O2) (seeFIGS.2and4). The unit case21accommodates therein the background light source22, the battery23, the background light controller24, and the background light operation device25. The unit case21includes an opening21athat can transmit the background light projected from the background light source22, and a charging terminal21bfor charging the battery23. The charging terminal21bis exposed to the outside of the unit case21. The unit case21can be formed into rectangular, cylindrical, triangular pyramidal, or any other shape.

The background light source22is a light source of the background light that illuminates the surroundings of a projection region of the slit light. The background light source22is capable of outputting visible light used for naked-eye observation and photography. For example, a halogen lamp, LED, etc. can be used therefor. The background light source22is capable of changing its luminous intensity (light quantity) depending on the amount of the applied power. The background light source22according to the first embodiment is capable of outputting an infrared light used for observing and photographing the meibomian gland so that it is configured to output the light by suitably selecting the visible light source or the infrared light source. Alternatively, the background light source22may be configured to output the light from only one of the visible light source and the infrared light source.

The battery23is a source of electric power supply to the background light source22, the background light controller24, etc. In the first embodiment, the battery23is a secondary battery that can be repeatedly used by charging through the charging terminal21b. As such battery23, a nickel metal hydride battery or a lithium-ion battery may be used.

The background light controller24includes a CPU and memory and controls the background light source22based on commands input from the background light operation device25and the after-mentioned main controller31. The background light controller24controls the amount of power applied from the battery23to the background light source22and suitably changes the ON/OFF state of the background light source22, luminous intensity (intensity of the background light), and the like. The background light operation device25is an operation device operated by the examiner, etc. and includes a switch(es), a button(s), dial(s), etc. The background light operation device25is provided on the surface of the unit case21to be exposed and is operable by the examiner. The background light operation device25can input any command according to the operation to the background light controller24. For example, it can input a command to change the ON/OFF state, light intensity, etc. of the background light source22.

The background illumination unit20may be configured to provide a lens that converges the background light projected from the background light source22. The background illumination unit20may be configured to illuminate the background without passing through the mirror12b.

(Configuration of Controller) The controller30that controls the slit-lamp microscope10will be described with reference toFIGS.2,6, etc. The controller30includes the main controller31that uses a CPU (Central Processing Unit). The main controller31acquires necessary information and suitably outputs control commands to the illumination system12, the observation system13, and the background illumination unit20(its background light controller24) of the slit-lamp microscope10. The control program is stored in advance in the after-mentioned storage32. The control commands from the main controller31are realized by the cooperation of the control program and hardware. To the main controller31, the storage32, a display33, a main operation device34, and the brightness adjustment knob14care connected.

The main controller31is configured to include a microprocessor, RAM, ROM, a hard disk drive, and the like. In the hard disk drive, the control program is stored in advance. The main controller31is operated by the cooperation of the control program and the above-mentioned hardware. The main controller31performs overall control of the slit-lamp microscope10(illumination system12, observation system13, background illumination unit20, etc.) based on input operations to the main operation device34and the brightness adjustment knob14c. The main controller also reads data stored in the storage32and writes data to the storage32.

The main controller31(its light intensity adjuster51) adjusts the amount of power applied to the light source121of the illumination system12in accordance with the rotational operation to the brightness adjustment knob14c, thereby changing the light intensity (light quantity) of the light source121. Therefore, the main controller31functions as a controller that controls the light source121. The main controller31also conducts control of the charge accumulation time, control of the light receiving sensitivity, control of frame rate, and the like in the image sensor13eof the observation system13, and acquires image signals generated by the image sensor13e. Furthermore, the main controller31can conduct control of the background light controller24, that is, control of operation of the background light source22of the background illumination unit20through the background light controller24. The main controller31receives operation (its signals) conducted on the background light operation device25of the background illumination unit20. The main controller31changes the light intensity (light quantity) of the background light source22by adjusting the amount of power applied to the background light source22in accordance with, for example, the operation conducted on the main operation device34and the background light operation device25.

The storage32is configured to include ROM (Read Only Memory), RAM (Random Access Memory), a hard disk drive, and the like, and various data and computer programs can be written into and read out of it.

The display33is formed by LCD (Liquid Crystal Display) or the like and displays various information by receiving control commands from the main controller31. The display33is installed on the base14or in its vicinity to be visible to the examiner. The display33may be installed on the microscope body11or in other locations, as long as it is visible to the examiner.

The main operation device34is formed of operation devices and input devices, such as the operation panel, switch, button, dial, trackball, mouse, keyboard, etc. The main operation device34is operated by the examiner, and any commands in response to the operation are input to the main controller31. The operation handle14binstalled on the base14may also be included in the main operation device34. The display33and the main operation device34may be separately provided, but they may be integrated at least in part by using a touch screen, etc.

To the main controller31, a magnification detector41, a slit distance (slit width) detector42, an aperture detector43, a filter detector44, and a slit light detector45are connected. These five detectors output the detection results (their signals), which are detected by themselves, to the main controller31.

The magnification detector41detects the magnification set in the magnification optical system132of the observation system13, that is, the state of switching of the magnification lens group. The magnification detector41can be configured, for example, to provide a readout portion (e.g., a tag) on a support frame or the like for supporting each magnification lens to be moved, and to provide a detector for detecting the readout portion of the magnification lens on the optical path. The magnification detector41is not limited to the configuration of the first embodiment but also may be another configuration, as long as it detects magnification in the magnification optical system132and outputs detected values to the main controller31.

The slit distance detector42detects the distance (slit width) between the two slit blades125a,125bin the slit portion125. The slit distance detector42may be configured, for example, to use a position sensor to detect the positions of the two slit blades125a,125b. The slit distance detector42may be configured to use a position sensor to detect the positions of driving points of both slit blades125a,125bin the slit portion125. Furthermore, the slit distance detector42may also be configured to use a light intensity sensor that detects the light intensity projected from between both slit blades125a,125b, and to make a calculation from the relationship between the detection result and the light intensity of the light source121. In addition, the slit distance detector42may also be configured to conduct a determination from the width of the projected slit light based on the image signals (acquired image) from the image sensor13e. The slit distance detector42is not limited to the configuration of the first embodiment but also may be another configuration, as long as it detects the distance (slit width) between the two slit blades125a,125bin the slit portion125and outputs detected values to the main controller31. Thus, the slit distance detector42functions to detect whether or not the pair of slit blades125a,125bis closed.

The aperture detector43detects the size (diameter, aperture area) of a light transmitting part in the illumination diaphragm123of the illumination system12. The aperture detector43may be configured, for example, to include a position sensor in a mechanism that changes the size of the light-transmitting part of the illumination diaphragm123. The aperture detector43may also be configured to use a light intensity sensor that detects the light intensity of the light transmitted through the light transmitting part and to make a calculation from the relationship between the detection result and the light intensity of the light source121. The aperture detector43is not limited to the configuration of the first embodiment but also may be another configuration, as long as it detects the size (diameter, aperture area) of the light transmitting part in the illumination diaphragm123and outputs detected values to the main controller31.

The filter detector44detects whether or not in the illumination system12the filter F is inserted into the optical path by the filter portion129and also detects the type of the filter F when inserted. The filter detector44may be configured, for example, to include a readout portion (e.g., a tag) on a support frame or the like for supporting each filter F, and to include a detector for detecting the readout portion of the filter F on the optical path. The filter detector44is not limited to the configuration of the first embodiment but also may be another embodiment, as long as it detects whether or not the filter F is inserted into the optical path and detects the type of the filter F when inserted.

The slit light detector45detects the state of the slit light projected toward the subject eye E. This state of the slit light means whether or not the slit light is in a desired single band form with a set length. The slit blades125a,125bform the slit light by the light from the light source121that passes through the distance d. Accordingly, the light from the light source121is blocked by entirely contacting the slit blades125a,125beach other, that is the eliminating the distance d between the slit blades125a,125b. However, high precision is required to entirely contact the slit blades125a,125beach other to prevent the light from leaking from the light source121. Therefore, it is difficult to make the distance d between the slit blades125a,125bcompletely uniform for preventing the leakage of the light from the light source121, and accordingly, even when the two slit blades125a,125bare brought into contact with each other, the contact of the slit blades125a,125bbecomes partial contact. However, the variation of the distance d between the two slit blades125a,125bis actually extremely small. Therefore, the slit blades125a,125bdo not cause any problems except when the slit blades125a,125bcontact each other to block the light. When the slit blades125a,125bcontact with each other or the distance between the slit blades125a,125bbecomes close to the contact, the slit light may not be seen as a single straight band but may be seen as an interrupted band or multiple aligned bands.

The slit light detector45detects whether the slit light is in an intended single straight band, or in an unintended band or bands such as the interrupted band, or the multiple aligned bands. The slit light detector45can be configured, for example, to conduct a determination from the width of the projected slit light, based on the image signals (acquired image) from the image sensor13e. The slit light detector45is not limited to the configuration of the first embodiment but may be another configuration as long as it detects the state of the slit light and outputs the main controller31.

The main controller31may be configured to also change the diaphragm133(its stop or aperture value) as a control of the observation system13in accordance with operation on the main operation device34or the like. Furthermore, the main controller31may be configured to separately rotate the first and second support arms15b,15cin accordance with the operation on the main operation device34by controlling the arm drive mechanism.

(Configuration of Light Intensity Adjustment) The main controller31according to the first embodiment includes the light intensity adjuster51, a slit distance determiner52, a slit light determiner53, and a background illumination determiner54. The light intensity adjuster51is one to adjust the magnitude of the power applied to the light source121. Basically, it adjusts the magnitude of the applied power in accordance with the operation on the brightness adjustment knob14cor the like. As described hereinafter, the light intensity adjuster51stops the electric power application to the light source121according to the detection result from the slit distance determiner52or the detection result from the slit light determiner53.

Here, the light intensity adjuster51basically adjusts the range of rotational operation of the brightness adjustment knob14cso that the light intensity ranges from zero upon turning off to the maximum, and changes the applied power so that the light intensity increases or decreases in proportion to the rotational movement of the brightness adjustment knob14c. As described hereinafter, the light intensity adjuster51stops the power application to the light source121when the slit distance determiner52has determined that the slit blades125a,125bare closed, or when the slit light determiner53has determined that the slit light is not in a proper condition. As described hereinafter, under the condition that the power application to the light source121is stopped, when the slit distance determiner52has determined that the slit blades125a,125bare opened, the light intensity adjuster51starts the power application to the light source121and adjusts the magnitude of the applied power in accordance with the operation on the brightness adjustment knob14cor the like.

Based on the detection result from the slit distance detector42, the slit distance determiner52determines the distance d between the two slit blades125a,125bin the slit portion125. The slit distance determiner52according to the first embodiment determines whether or not the acquired or detected distance d is less than or equal to a set distance ds. In the slit portion125, the set distance ds is set, based on a position where the slit blades125a,125bare closed in design. Therefore, the fact that the acquired distance d is equal to the set distance ds means that the two slit blades125a,125bare in a positional relationship that they are set as being closed, irrespective of whether or not they are actually closed. The slit distance determiner52determines from the detection result obtained by the slit distance detector42that the distance d has become equal to the set distance ds as a result of the movement of the two slit blades125a,125brelative to each other to the set closed position.

The slit light determiner53determines whether or not the slit light is in a proper condition based on the detection result from the slit light detector. This proper condition means that the slit light is substantially in an intended single straight band form. In contrast, an improper condition means that the slit light is an unintended one such as a band form interrupted in the middle or a plurality of separate, aligned, band-like portions.

The background illumination determiner54determines whether or not the background illumination unit20(background light source22) is set to emit infrared light based on the signals from the background light controller24of the background illumination unit20. The background illumination determiner54according to the first embodiment is configured to be able to select a visible light source and an infrared light source. Therefore, it determines whether or not the background illumination unit20is attached to a proper position and is in an operable condition. If determined that it is attached thereto and is in the operable condition, it determines whether or not the infrared light source is selected. In case that the background illumination unit20is configured to be able to output only an infrared light source, the background illumination determiner54may determine whether or not the background illumination unit20is attached thereto and whether or not the background illumination unit20is in an operable condition.

(Light Intensity Adjustment Control) Next, the processing structure of the light intensity control conducted in the main controller31will be described with reference to the flowchart shown inFIG.7. The light intensity control processing is started when the power switch of the slit-lamp microscope10is turned on and is repeatedly conducted until the power switch is turned off.

In Step S1, the light intensity of the light source121is adjusted and then the process proceeds to Step S2. In Step S1, the light intensity adjuster51changes the applied power in accordance with the rotational operation on the brightness adjustment knob14c, that is, the rotational position of the brightness adjustment knob14c, to adjust the light intensity of the light source121. In Step S1, the light source121is kept turned off even if the rotational operation is conducted on the brightness adjustment knob14c, in case that the light source121is turned off in Steps S6and S7after determining that the pair of slit blades125a,125bis closed in Step S3or that the slit light is not in a proper condition in Step S4.

In Step S2, it determines whether or not the slit opening/closing knob125cwas operated. If YES, it proceeds to Step S3. If NO, it returns to Step S1. In Step S2, it determines whether or not the distance (slit width) between the two slit blades125a,125bdetected by the slit distance detector42is changed. If YES in Step S2, in case that the light source121is turned off by Step S7, the light source is turned on. Furthermore, if YES in Step S2, in case that the light source121is turned off while the background illumination unit20is turned on by Step S6, the light source121is turned on and the background illumination unit20is turned off. Here, in case that the light source121is turned off by Steps S6and S7, there is a situation after determining that the pair of slit blades125a,125bis closed by Step S3or that the slit light is not in a proper condition by Step S4. Therefore, the determination that the slit opening/closing knob125cwas operated means that the pair of slit blades125a,125bwas opened. Therefore, in Step S2, as the pair of slit blades125a,125bwas opened, the light source121is turned on. At this time, in Step S2, the light source121is turned on with a power according to the rotational position of the brightness adjustment knob14c, that is, with the brightness set by the brightness adjustment knob14c.

In Step S3, it determines whether or not the pair of slit blades125a,125bis closed. If YES, it proceeds to Step S5. If NO, it proceeds to Step S4. In Step S3, the slit distance determiner52determines whether or not the distance d between the two slit blades125a,125bis less than or equal to the set distance ds.

In Step S4, it determines whether or not the slit light is in a proper condition. If YES, it returns to Step S1. If NO, it proceeds to Step S5. In Step S4, the slit light determiner53determines whether or not the slit light is in the proper condition. In a situation where the pair of slit blades125a,125bis opened to turn on the light source121in Step S2after the light source121is turned off by Steps S6and S7, it is determined as NO in Steps S3and S4and the process returns to Step S1.

In Step S5, it determines whether or not it is set to emit an infrared light. If YES, it proceeds to Step S6. If NO, it proceeds to Step S7. In Step S5, the background illumination determiner54determines whether or not it is set to emit an infrared light in the background illumination unit20and further determines in the first embodiment whether or not the infrared light source is selected in the background illumination unit20.

In Step S6, the light source121is turned off and the background illumination unit20is turned on, thereby terminating this light intensity control process. In Step S6, the light intensity adjuster51stops the power application to the light source121and the main controller31outputs a signal for turning on the background light source22to the background light controller24.

In Step S7, the light source121is turned off to terminate this light intensity control process. In Step S7, the light intensity adjuster51stops the power application to the light source121.

(Configuration of Status Indicator) As shown inFIG.8, in the observation system13of the slit-lamp microscope10, a status indicator60is provided. The status indicator60indicates whether the light source121is turned on or off, and can be seen by the examiner as an observer. The status indicator60according to the first embodiment uses a transparent display and is disposed on the observation optical axis O2of the observation system13. The status indicator60indicates whether or not the light source121is turned on or off at a position that does not interfere with the observation of the subject eye E by the observation system13. InFIG.8, the status indicator60includes an ON/OFF indication point61near the upper end. The status indicator60does not interfere with the observation of the subject eye E by not displaying anything below the ON/OFF indication point61.

The status indicator60indicates whether the light source121is turned on or off by letters, and makes it easy to grasp which state it is in. The ON/OFF indication point61according to the first embodiment is configured to display “LIGHT SOURCE OFF” when the light source121is turned off, and not display anything when the light source121is turned on. With this, the examiner can easily recognize whether the light source121is turned on or off by the ON/OFF indication point61while maintaining a condition of observing the subject eye E by the observation system13. The status indicator60is not limited to the configuration of the first embodiment, but may be one with a different display mode or one with a display even when it is turned on or one with another configuration as long as the examiner as an observer can visually recognize whether the light source121is turned on or off.

(Operation of Light Intensity Adjustment) Next, operation to observe the subject eye E by using the slit-lamp microscope10will be described. The slit-lamp microscope10makes it possible to observe the subject eye E irradiated with the slit light with any brightness by suitably operating the observation magnification operation knob13c, the brightness adjustment knob14cand the slit opening/closing knob125c.

At this time, in the slit-lamp microscope10, for example, when the rotational operation has not been conducted on the slit opening/closing knob125cor has been conducted on the slit opening/closing knob125cin a range not to be the fully closed rotational position, the light intensity of the light source121is adjusted in accordance with the operation amount (rotational position) of the brightness adjustment knob14cin Step S1to proceed to Step S2. Then, in the slit-lamp microscope10, when the slit opening/closing knob125cis not at the fully closed rotational position, and then when the slit light that has been formed from the light source121via the pair of slit blades125a,125bis in a proper condition, the process proceeds in the order of Steps S3, S4and S1. In this manner, the above operation is repeated, thereby making it possible to observe the subject eye E irradiated with the slit light with any brightness.

Here, in the slit-lamp microscope10, when the slit opening/closing knob125chas been rotated until the fully closed rotational position, the process proceeds in the order of Steps S1, S2, S3, and S5and it determines whether or not it is set to emit an infrared light in the background illumination unit20. In case that it is set to emit an infrared light in the background illumination unit20, the process proceeds to Step S6. In Step S6, the light source121is turned off and the background illumination unit20is turned on. With this, in the slit-lamp microscope10, when projecting infrared light, it is possible to prevent visible light from mixing therewith and it is possible to properly conduct observation and photographing of the meibomian gland by projecting infrared light. In the slit-lamp microscope10, it is possible to turn into a condition of projecting infrared light by the background illumination unit20by only operating the slit opening/closing knob125c. Therefore, it is possible to smoothly proceed to observation and photographing of the meibomian gland. In case that it is not set to emit infrared light in the background illumination unit20, the process proceeds to Step S7to turn off the light source121. Therefore, in the slit-lamp microscope10, in a condition that the pair of slit blades125a,125bis closed, it is possible to prevent seeing the light that escapes from a gap between the slit blades125a,125b, thereby giving an impression as having a high quality.

In the slit-lamp microscope10, in the case that the rotational operation has been conducted on the slit opening/closing knob125cin a range not to be the fully closed rotational position, but the generated slit light is not in a proper condition, the process proceeds in the order of Steps S1, S2, S3, S4, and S5. In Step S5, it determines whether or not it is set to emit infrared light in the background illumination unit20. In the slit-lamp microscope10, in the case that it is set to emit infrared light in the background illumination unit20, the process proceeds to Step S6. In Step S6, the light source121is turned off and the background illumination unit20is turned on. In contrast, in the case that it is not set to emit infrared light in the background illumination unit20, the process proceeds to Step S7to turn off the light source121.

In this way, in the slit-lamp microscope10, in the case that the generated slit light is not in a proper condition although the slit opening/closing knob125cis not at the fully closed rotational position, it determines that the pair of slit blades125a,125bis substantially closed. As a result, the light source is turned off and the background illumination unit20is turned on. Here, in the slit-lamp microscope10, in the case that the generated slit light is not in a proper condition, it determines that the slit opening/closing knob125cis at a rotational position that is extremely close to the fully closed rotational position, since the two slit blades125a,125bare partially in contact with or extremely close to each other. Therefore, in this case, it is considered that the examiner has tried to substantially close the pair of slit blades125a,125b. Furthermore, in the slit-lamp microscope10, it is difficult to conduct a proper observation of the subject eye E by projecting the slit light not in a proper condition. Thus, in the slit-lamp microscope10, although the slit opening/closing knob125cis not at the fully closed rotational position, it causes no problem to determine that the pair of slit blades125a,125bis substantially closed. As a result, in the slit-lamp microscope10, it is possible to give an impression as the slit-lamp microscope10has high quality and to conduct an appropriate observation of the subject eye E using infrared light by turning off the light source121and turning on the background illumination unit200when the generated slit light is not in a proper condition.

Then, in the slit-lamp microscope10, under a condition that the light source121is turned off and the background illumination unit20is suitably turned on, when the slit opening/closing knob125cis rotated from the fully closed rotational position in a direction to open the slit, the process proceeds from Step S1to Step S2to turn on the light source121and suitably turn off the background illumination unit20. Furthermore, in the slit-lamp microscope10, under a condition that the light source121is turned off, when the slit opening/closing knob125cis rotated from the fully closed rotational position in a direction to open the slit, the process proceeds from Step S1to Step S2to turn on the light source121. Thus, in the slit-lamp microscope10, irrespective of whether the background illumination unit20is turned on or not, it is possible to smoothly proceed to an observation of the subject eye E using the slit light by only operating the slit opening/closing knob125cto open the pair of slit blades125a,125bfrom a condition that the light source121is turned off.

Next, the task of art of slit-lamp microscopes will be described. In conventional slit-lamp microscopes, it is possible to obtain a condition that the subject eye is not irradiated with the slit light by closing the pair of slit blades, that is, bringing the two slit blades into contact with each other to eliminate the slit, thereby blocking the light from the light source at the both slit blades. In such slit-lamp microscopes, however, unless extremely improving the processing and assembly precisions of the slit blades, even if the two slit blades are brought into contact with each other, it is difficult to achieve contact with a precision that can prevents the light from escaping in the entire area in the longitudinal direction of the slit. Therefore, in such slit-lamp microscopes, even if the two slit blades are moved to their contact position, a gap(s) is formed between the two slit blades. As a result, the light escaping from the gap(s) may reach the subject eye. With this, in such slit-lamp microscopes, the gap(s) formed between the two slit blades may be recognized by the examinee or examiner, thereby giving an impression as having a low quality.

In contrast, in the slit-lamp microscope10of the present disclosure, when the main controller31controlling the light source121determines that the pair of slit blades has been closed, the light source121is turned off. Therefore, in the slit-lamp microscope10, when the two slit blades125a,125bhave been moved to the position where the slit blades125a,125bare closed (where the slit blades125a,125bare in contact with each other), there is no light from the light source121. Therefore, irrespective of the processing and assembly precisions of the slit blades125a,125b, it is possible to certainly prevent escaping of the light from the gap(s). With this, in the slit-lamp microscope10, under the condition that the pair of slit blades125a,125bis closed, there is no light escaping from the gap(s) and reaching the subject eye E. This can prevent giving an impression as having a low quality. Furthermore, in the slit-lamp microscope10, there is no need for processing and assembling the pair of slit blades125a,125bwith an extremely high precision that enables preventing light escape in the entire area of the slit. Therefore, it is possible to prevent the increase of the cost and the production steps resulting from the increase of the processing and assembling precisions.

The slit-lamp microscope10according to the first embodiment of the present disclosure includes an illumination system12that is configured to project a slit light onto a subject eye E; a slit portion125that is configured to form the slit light having a width by passing a light from a light source121through a slit between a pair of the slit blades125a,125bin the illumination system12; and a main controller31that is configured to control the light source121. The main controller31is configured to turn the light source121off when the two slit blades125a,125bare closed. Therefore, when the two slit blades125a,125bare closed, there is no light from the light source121. With this, irrespective of the processing and assembly precisions of the pair of slit blades125a,125b, it is possible to certainly prevent escaping of the light from the gap(s).

The slit-lamp microscope10further includes a slit distance detector42that is configured to detect a distance d between the two slit blades125a,125b. When the main controller31determines that the distance d between the two slit blades125a,125bis equal to or smaller than the set distance ds based on a detection result from the slit distance detector42, the main controller31determines that the two slit blades125a,125bare closed to turn the light source121off. In this slit-lamp microscope10, when the distance d is equal to or smaller than the set distance ds in a set positional relationship between the two slit blades125a,125b, it is determined that the two slit blades125a,125bare closed. Therefore, irrespective of the processing and assembly precisions of the pair of slit blades125a,125b, it is possible to turn the light source121off at a set position therebetween. This can prevent product-to-product variation.

The slit-lamp microscope10further includes a slit opening/closing knob125cthat is configured to adjust the distance d between the two slit blades125a,125bby a rotational operation thereof. The slit opening/closing knob125cis configured such that a rotation resistance against the rotational operation of the slit opening/closing knob125cpartially changes when the slit opening/closing knob125cis in a rotational position (the fully closed rotational position) to close the distance d between the two slit blades125a,125b. Therefore, in the slit-lamp microscope10, the examiner operating the slit opening/closing knob125ccan recognize the fully closed rotational position by a finger sensation, thereby causing no sense of discomfort that the light source121was turned off. This may result from the examiner's imagination that, at the fully closed rotational position, the pair of the slit blades125a,125bshould actually be fully closed, thereby causing the slit light disappear.

The slit-lamp microscope10further includes a slit light detector45that is configured to detect a condition of the slit light. The main controller31is configured to turn the light source121off when the main controller31determines that the condition of the slit light is out of a proper condition based on a detection result of the slit light detector45. In the slit-lamp microscope10, the light source121is turned off when it is determined that the condition of the slit light is out of a proper condition, in addition to when it is determined that the two slit blades125a,125bare closed. Therefore, in the slit-lamp microscope10, when the two slit blades125a,125bare brought into a partial contact with each other or an extremely close position to each other, it is determined that the slit blades125a,125bare substantially closed and the light source121is turned off. This operation conforms to the examiner's intention and can prevent the examiner from not being able to properly observe the subject eye E.

The slit-lamp microscope10further includes an observation system13that is configured to observe or photograph a reflection light on the subject eye E; and a background illumination unit20that is configured to irradiate the subject eye E with an infrared light. In the slit-lamp microscope10, the main controller31is configured to start irradiating the subject eye E with the infrared light by the background illumination unit20when the main controller31determines that the two slit blades125a,125bare closed to turn the light source121off. Therefore, it is possible to proceed to an infrared light irradiation condition by the background illumination unit20by only closing the two slit blades125a,125b. Furthermore, it is possible to conduct observation and the like by the infrared light irradiation while preventing visible light from mixing with the infrared light.

In the slit-lamp microscope10, the main controller31is configured such that, when the two slit blades125a,125bare opened, the light source121is turned on and the infrared light irradiation by the background illumination unit20is stopped. Therefore, in the slit-lamp microscope10, it is possible to smoothly proceed to an observation of the subject eye E by only opening the two slit blades125a,125b.

The slit-lamp microscope10further includes an observation system13that is configured to observe or photograph a reflection light reflected by the subject eye E. The observation system13includes a status indicator60that is configured to indicate a condition that the light source121is turned on or off. Therefore, in the slit-lamp microscope10, while the examiner maintains a condition of observing the subject eye E by the observation system13, the examiner can recognize the current lighting state of the light source121, thereby alleviating discomfort caused by turning the light source121off.

As above, the slit-lamp microscope according to the first embodiment of the present disclosure has been described. However, the specific configuration of the present disclosure is not limited to the first embodiment. Changes and additions in design should be allowed as long as they do not deviate from the gist of the inventions recited in the claims.

In the first embodiment, the background illumination unit20capable of projecting infrared light is attached. However, it is not limited to the configuration of the first embodiment. The background illumination unit20may not be attached, or the background illumination unit20not projecting infrared light may be attached. In such a case, in the flowchart shown inFIG.7, Steps S5and S6may be omitted and the process proceeds to Step S7if YES in Step3and if NO in Step S4.

In the first embodiment, it is determined whether or not the acquired distance d (slit width) between the two slit blades125a,125bis equal to or smaller than the set distance ds by using the slit distance detector42that is configured to detect the distance d therebetween. However, it is not limited to the configuration of the first embodiment. It is optional to use a slit opening/closing detector that is configured to detect whether or not the two slit blades125a,125bare closed by another method.