JP2011147043A - Oral camera, and illumination control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the elevation of a temperature in an imaging window portion in an oral camera. <P>SOLUTION: An oral camera includes an illumination control section 24 for controlling illuminance of an illumination section 23, and a lightness detecting means for detecting subject information from an imaging section 10b. A control section 22 sets the illuminance of the illumination section 23 based on the amount of change in lightness of the subject information detected by the lightness detecting means at the time when the illumination control section 24 changes the illuminance of a subject from the illumination section 23. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an intraoral camera and a method for controlling illumination thereof.

  The conventional intraoral camera has the following configuration.

  That is, a main body case, an intraoral insertion portion attached to the front side of the main body case, a lens barrel provided in the intraoral insertion portion, a plurality of lenses provided in the lens barrel, and a front of the lens barrel An illumination element provided in the main body case, having an imaging window provided in the intraoral insertion portion corresponding optically in a side opening, and an imaging device optically connected to a rear side opening of the lens barrel Is configured to pass through the lens barrel through an optical path and to be supplied to the imaging window portion (for example, Patent Document 1 below).

Japanese translation of PCT publication No. 2004-532083

  The problem in the conventional example is that the temperature rise in the imaging window portion becomes large.

  That is, since an appropriate intraoral image cannot be obtained unless strong light is supplied to the imaging window portion, extremely strong light is supplied to the imaging window portion from the illumination element. The increase in temperature of the imaging window portion is increased by light.

  One of the harmful effects of the temperature rise in the imaging window portion is that heat is applied to the vicinity of the imaging window portion in the oral cavity, and this heat causes discomfort.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to suppress a temperature rise in an imaging window portion.

  In order to achieve this object, the present invention provides a main body case, an intraoral insertion portion attached to the front side of the main body case, and an optical subject disposed in the front opening of the intraoral insertion portion. An imaging window for capturing, a lens unit optically coupled to the imaging window, an imaging unit for capturing optical subject information from the lens unit, and an illumination unit arranged around the imaging window, An illumination control unit that controls the illuminance of the illumination unit and a brightness detection unit for subject information from the imaging unit are provided, and the illumination control unit is configured to change the brightness when the illuminance of the illumination unit is changed. The illuminance of the illumination unit is set from the amount of change in the brightness of the subject information detected by the height detection means, thereby achieving the intended purpose.

  As described above, the present invention includes a main body case, an intraoral insertion portion attached to the front side of the main body case, an imaging window that optically captures an object, disposed at the front opening of the intraoral insertion portion, A lens unit optically coupled to the imaging window; an imaging unit that captures optical subject information from the lens unit; and an illumination unit disposed around the imaging window. An illumination control unit to be controlled and a brightness detection unit for subject information from the imaging unit are provided, and the illumination control unit is detected by the brightness detection unit when the illuminance of the illumination unit is changed. Since the illuminance of the illumination unit is set based on the amount of change in brightness of the subject information to be performed, an increase in temperature of the imaging window portion can be suppressed.

  That is, in the present invention, when the illumination control unit changes the illuminance of the subject from the illumination unit, the amount of change in brightness of the subject information detected by the brightness detection unit is determined. The magnitude of the amount of change makes it possible to estimate the degree of influence of the illuminance of the illumination unit on the subject, and the illuminance of the illumination unit can be reduced according to the degree of influence of the illumination. The temperature rise can be suppressed.

The perspective view of one Embodiment of this invention Cross section The exploded perspective view Cross section of the lens barrel Bottom view of the intraoral insertion part Functional block diagram Control flow chart Control flow chart Control timing diagram

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  In FIG. 1, reference numeral 1 denotes a substantially cylindrical main body case, and a power source and signal cord 2 is connected to the rear end side of the main body case 1.

  Further, an intraoral insertion portion 3 is attached to the front side of the main body case 1, and a lens barrel 4 shown in FIGS. 2 and 3 is provided in the intraoral insertion portion 3.

  As shown in FIGS. 3 and 4, the lens barrel 4 has a configuration in which the diameter of the opening gradually increases from the front opening 4 a toward the rear opening 4 b, and a lens group is included in the lens barrel 4. As shown in FIG. 4, four groups of lenses G1 to G4 are arranged as the lens unit.

  Specifically, first, the lens group G1 of the first group is inserted from the rear side opening 4b of the lens barrel 4 and pushed into the front side opening 4a portion of the lens barrel 4 as shown in FIG. The outer periphery of the lens is brought into contact with the inner surface of the lens barrel 4, and positioning is performed in this state.

  Subsequently, the spacer cylinder 5 is pushed into the lens group G1 from the rear opening 4b of the lens barrel 4, and positioning is performed in this state.

  Next, the second and third lens groups G2 and G3 are inserted from the rear opening 4b of the lens barrel 4, and pushed into the spacer cylinder 5 as shown in FIG. 4, and positioning is performed in this state.

  Next, the spacer cylinder 6 is pushed into the lens group G3 from the rear opening 4b of the lens barrel 4, and positioning is performed in this state.

  Next, the fourth lens group G4 is inserted from the rear opening 4b of the lens barrel 4, and pushed into the spacer cylinder 6 as shown in FIG. 4, and positioning is performed in this state.

  Next, the spacer cylinder 7 is pushed into the lens group G4 from the rear opening 4b of the lens barrel 4, and positioning is performed in this state.

  Now, an imaging window 3a is provided in the lower surface portion of the intraoral insertion portion 3 optically corresponding to the front opening 4a of the lens barrel 4, and the imaging window 3a and the front opening 4a of the lens barrel 4 are provided. A prism 8 is provided between the two.

  Further, as shown in FIG. 5, the imaging window 3 a has a quadrangular shape, and two illumination elements 9 are arranged on the front and rear sides facing each other. On the other hand, a focus unit 10 shown in FIG. 3 is optically connected to the rear opening 4b of the lens barrel 4.

  In the above configuration, when an intraoral image is acquired, the intraoral insertion portion 3 shown in FIG. 1 is inserted into the oral cavity, and the imaging element is illuminated by the illumination element 9 in this state. At this time, the images obtained from the imaging window 3a are the prism 8, the lens groups G1, G2, G3, and G4, and the fifth and sixth lens groups G5 and G6 shown in FIG. Is sent to the imaging unit 10b, and then displayed on the monitor via the code 2.

  When a desired imaging region is found while looking at the monitor, if the imaging button 11 shown in FIG. 1 is pressed, the image at that time is recorded as a still image in the memory in the monitor.

  In this state, in this embodiment, since the illumination element 9 is arranged in the imaging window 3a, that is, the illumination element 9 is arranged in the vicinity of the imaging part, the illumination from the illumination element 9 is not increased. However, a sufficiently clear image can be acquired.

  Therefore, the temperature of this imaging part is not increased abnormally.

  In the present embodiment, the front opening 4a of the lens barrel 4 is disposed in the vicinity of the imaging window 3a, and the lens barrel 4 is made of metal.

  For this reason, the heat of the imaging window 3a can be effectively transferred from the front opening 4a of the lens barrel 4 to the rear opening 4b, and as a result, the temperature rise of the imaging window 3a is suppressed. can do.

  That is, at the time of this photographing, even if the imaging window 3a part contacts the skin or teeth in the oral cavity, an abnormally high temperature is not felt, and a comfortable photographing operation can be performed.

  Further, if the lens barrel 4 is made of metal, the processing accuracy can be increased, and therefore the lens groups G1 to G4 can be appropriately arranged at predetermined positions in the lens barrel 4.

  Further, in order to appropriately arrange the lens groups G1 to G4 as described above, the spacer cylinders 5, 6, and 7 are also made of metal that is easy to obtain processing accuracy. However, these spacer cylinders 5, 6, and 7 are provided with a black coating at least on the inner surface side to prevent unnecessary reflection of light.

  Next, the configuration of focus control will be described.

  As a drawing, description will be given returning to FIG. 1 again.

  The front portion (the left portion in FIG. 1) of the main body case 1 in FIG. 1 has a cylindrical shape with a smaller diameter than the rear portion of the main body case 1 for insertion into the oral cavity. The front portion of the main body case 1 is an intraoral insertion portion 3.

  As shown in FIG. 2, the intraoral insertion portion 3, which is the front portion of the main body case 1, is captured by an imaging window 3 a, a prism 8, and lens groups G <b> 1, G <b> 2, G <b> 3, G <b> 4 provided in the lens barrel 4. The image obtained from the imaging window 3a is arranged so as to pass through the lens group G1, G2, G3, G4 provided in the lens barrel 4 via the prism 8.

  Next, a focus unit 10 optically connected to the lens groups G1, G2, G3, and G4 is disposed at the rear portion of the main body case 1. The configuration of the focus unit 10 will be described in more detail. As shown in FIG. 3, the focus unit 10 includes a focus lens unit 10a and an imaging unit 10b disposed behind the focus lens unit 10a from the front side.

  First, the focus lens unit 10a includes a focus lens cover holder 13, a focus lens front cover 14, lens groups G5 and G6, a drive motor 15 for driving the lens groups G5 and G6, and a movable unit 16 thereof. The first guide pole 17, the second guide pole 18, and the focus lens rear cover 19 are configured.

  The operation of the components of the focus lens unit 10a will be described. Images that have passed through the lens groups G1, G2, G3, and G4 provided in the lens barrel 4 are sent to the lens groups G5 and G6. The second and sixth lens groups G5 and G6 form a pair of cemented lenses with two lenses. The function of these cemented lenses is to correct chromatic aberration of an image. Is configured as a focus lens movable in the optical axis direction so that the focal length can be automatically adjusted with respect to the distance to the subject.

  The operation as the focus lens will be described. The cemented lens made up of the lens groups G5 and G6 is held by the movable portion 16, and the movable portion 16 has a first guide pole 17 and a second guide pole 18 in it. Is slidably inserted.

  The rotational movement of the drive motor 15 is engaged with an inner gear (not shown) of the movable portion 16 by the lead screw 15a, and according to the rotational direction of the drive motor 15, the movable portion 16 is It will move back and forth in the direction of the optical axis.

  The first guide pole 17 and the second guide pole 18 are sandwiched and fixed between the focus lens front cover 14 and the focus lens rear cover 19 together with a diaphragm 20 for adjusting the brightness.

  Further, the connected focus lens front cover 14 and focus lens rear cover 19 are fixed to the main body case 1 and the lens barrel 4 by a focus lens cover holder 13.

  In addition, the image that has passed through the lens groups G5 and G6 is further sent to the rear image sensor 12.

  In such a configuration, the control unit (22 in FIG. 6) provided in the intraoral camera body adjusts the drive motor 15 so that the focal length of the subject of the electrical image obtained from the image sensor 12 is matched. While controlling, the lens groups G5 and G6 can be positioned with respect to the optical axis direction, and the focal length can be automatically adjusted. Therefore, in the intraoral camera, the imaging region and imaging window of the tooth that is the subject It is possible to freely adjust the subject distance from 3a, which increases convenience.

  Maintaining optical performance from the closest (close-up) to infinity with a fixed-focus lens is usually considered difficult due to large variations in focal position due to close-up and large variations in optical performance. This is even more so with a lens system with a field angle.

  In the present embodiment, the autofocus function can be introduced in spite of the lens system having a standard angle of view with a 35 mm equivalent focal length of about 40 mm. The focus lens unit 10a is placed in the rear focus unit 10 and the lens group is extended forward to the object side at the closest position, thereby improving the image plane characteristics and automatically changing the object distance from 0 mm to infinity. The autofocus function that can focus is realized.

  Furthermore, in the above configuration, a small-diameter lens barrel 4 is provided in the front part of the intraoral camera, a fixed lens group is arranged in the lens barrel 4, and an autofocus unit is provided on the rear side of the lens barrel 4. Therefore, since the intraoral insertion part 3 of the intraoral camera can be designed to have a small diameter, the intraoral camera can be downsized.

  Now that the basic configuration and operation of the present embodiment have been understood, the characteristic points of the present embodiment will be described below.

  As described above, since the illumination element 9 in the present embodiment is disposed in the vicinity of the imaging window 3a in order to obtain sufficient illuminance at the time of imaging, for example, in the case of close-up imaging of teeth in the oral cavity as a subject The imaging information of the intraoral teeth taken into the imaging unit 10b from the imaging window 3a is greatly affected by the light of the illumination element 9.

  In such a case, the brightness of the image set by the imaging unit 10b is affected by the light of the illumination element 9.

  However, when the imaging part is not an intraoral area but the front tooth or the entire face is photographed from outside the oral cavity, it is ambient light compared to the light of the illumination element 9, or used by room lighting or dentists As a result, there is a shooting state in which the illuminance of the illumination element 9 is not so necessary, and the imaging window 3a Continuing to set the illuminance of the surrounding illumination element 9 more than necessary increases the temperature of the distal end portion of the intraoral insertion section 3 and gives the patient discomfort.

  In such a problem, the configuration and feature points of the illumination control method and the intraoral camera will be described below.

  FIG. 6 shows a functional block diagram of the intraoral camera in the present embodiment.

  An imaging window 3a for optically capturing a subject is provided on the front side of the intraoral insertion portion 3 attached to the front side of the main body case 1, and optical subject information captured from the imaging window 3a is obtained from the imaging window 3a. The lens unit 21 is optically coupled to the lens unit 21. The lens unit 21 includes six lens groups G1, G2, G3, G4, G5, which perform optical conversion such as condensing, imaging, aperture, and focusing on subject information captured from the imaging window 3a. It is configured by G6.

The subject information optically converted by the lens unit 21 is taken into the imaging unit 10b and converted into an electrical video signal by the imaging device 12 arranged in the imaging unit 10b. With respect to the video signal from the imaging unit 10b, the control unit 22 drives the focus lens unit 10a in the focus unit 10 to control the position so that the subject is in focus.
The control unit 22 detects the position of the focus lens unit 10a as subject distance detection means, thereby detecting the subject distance from the imaging window 3a to the subject.

  In addition, the control unit 22 adjusts the optical brightness of the lens unit by adjusting the diaphragm 20 disposed in the lens unit 21.

  Furthermore, the control unit 22 can adjust the shutter speed by adjusting the input time of the optical video signal that enters the imaging unit 10b from the lens unit 21.

  As described above, the control unit 22 detects the brightness of the subject information as the brightness of the subject information based on the relationship between the aperture value for the aperture 20 disposed in the lens unit 21, the shutter speed, and the ISO sensitivity. The value can be calculated. As the brightness detection means of the subject information, an EV value may be used, but there is also a method of directly analyzing the brightness of the video signal from the imaging unit 10b and using the brightness information for determination.

  Next, the illumination unit 23 configured by the illumination element 9 provides illumination to the subject, and the illumination control unit 24 can adjust the brightness of the illumination unit 23.

  In the above configuration, the control unit 22 controls the illuminance of the illumination unit 23 through the illumination control unit 24 in order to match the luminance of the electrical video signal captured by the imaging unit 10b. Such control will be described with reference to the flowcharts of FIGS.

  In the illuminance control method in FIG. 7, the EV value is captured in step S1. The EV value at this time is a state in which the illumination of the illumination unit 23 is almost 100% bright.

  Next, in step S <b> 2, the control unit 22 sets the illumination state of the illumination unit 23 to a state of approximately 70% by the illumination control unit 24. Next, in this state, the EV value is acquired. In order to acquire a new EV value, the time for 10 fields is taken in step S3 as the time for stabilizing the illumination state. Thereafter, the EV value is acquired in step S4, and the change amount of the EV value is determined in step S5. If this amount of change is less than or equal to a predetermined value, it is determined that the influence of illumination is small, and in step S6, the illumination mode is switched to the extraoral mode, and the illuminance of the illumination unit 23 is reduced to 70%. When the change amount of the EV value is larger than the predetermined value, in step S7, the illumination control unit 24 sets the illuminance of the illumination unit 23 to be 100%.

  The amount of change in the EV value of the subject detected by the control unit 22 when the illumination control unit 24 changes the illuminance of the subject from the illumination unit 23 by performing the above-described illuminance control method of the illumination unit 23. The illuminance of the illuminating unit 23 can estimate the degree of influence on the subject, and the illuminance of the illuminating unit 23 can be set according to the degree of influence of the illumination. Therefore, the illuminance of the illumination unit 23 can be reduced according to the degree of the influence of the illumination, so that the temperature rise of the imaging window portion can be suppressed.

  Next, FIG. 8 shows a flowchart of a method for controlling the illuminance of the illumination unit 23 using the subject distance further.

  In the illuminance control flow of the illumination unit 23 shown in FIG. 8, not only the setting of the illuminance of the illumination unit 23 but also the distance between the imaging window 3a and the subject is determined from the amount of change in the EV value of the subject as described above. Information.

  First, in S01, it is determined whether or not the distance from the subject is 60 cm or more. If the determination result is true, that is, the subject is located far away, it is determined that the subject is not easily affected by illumination. In step S02, the EV value is fetched. The EV value at this time is a state in which the illumination of the illumination unit 23 is almost 100% bright.

  Next, in step S03, the illumination control unit 24 sets the illumination state of the illumination unit 23 to approximately 70%. Next, in this state, the EV value is acquired. In order to be able to acquire a new EV value, the time for 10 fields is taken in step S04 as the time for stabilizing the illumination state. Thereafter, the EV value is acquired in step S05, and the change amount of the EV value is determined in step S06. If the amount of change is less than or equal to a predetermined value, it is determined that the influence of illumination is small, and in step S07, the illumination mode is switched to the extraoral mode, and the illuminance of the illumination unit 23 is reduced to 70%. When the change amount of the EV value is larger than the predetermined value, the illumination control unit 24 sets the illuminance of the illumination unit 23 to 100% in step S08.

  By implementing such a method for controlling the illuminance of the illumination unit 23, not only the EV value of the subject but also whether or not the subject distance from the imaging window 3a to the subject is greater than or equal to a predetermined distance is added to the determination. Since the estimation of the degree of influence of the illuminance of the illumination unit 23 on the subject is more reliably performed, the illuminance of the illumination unit 23 can be more reliably adjusted.

  The setting of the EV value of the subject and the illuminance of the illumination unit 23 will be described in more detail.

  In the intraoral camera of the present embodiment, a setting with a relatively high shutter speed, for example, a shutter speed of 1/125 or more is preferentially used, and in this setting of the shutter speed, the aperture value is set. Adjustment is performed so that sufficient brightness is captured in the imaging information.

  In such control, when the EV value variation is small relative to the illumination unit 23 variation, for example, when there is no shutter speed variation and the aperture value variation is small, the environment of the subject is the illumination unit 23. Therefore, the illumination intensity of the illumination unit 23 can be reduced. On the other hand, when the EV value fluctuation amount is large relative to the illumination unit 23 variation, for example, when the aperture value variation is large, and there is a shutter speed variation, the environment of the subject affects the illumination unit 23. Therefore, it is impossible to reduce the illuminance of the illumination unit 23.

  FIG. 9 shows the EV value capturing timing in this embodiment.

  A solid line represents the subject EV value 27 from the subject signal. The determination of setting the illuminance of the illumination unit 23 is performed by determining the magnitude of the subject EV value ΔEV28 when the illuminance of the illumination is reduced from about 100% to about 70%. If the timing of changing to 70% becomes too fast, the subject EV value 27 cannot be measured accurately. Therefore, the change in illuminance is changed in about 0.2 seconds as a stable waiting time. . By performing the control in such a time, the user can observe an image with an appropriate brightness almost in real time without discomfort in the displayed image.

  As described above, the present invention includes a main body case, an intraoral insertion portion attached to the front side of the main body case, an imaging window that optically captures an object, disposed at the front opening of the intraoral insertion portion, A lens unit optically coupled to the imaging window; an imaging unit that captures optical subject information from the lens unit; and an illumination unit disposed around the imaging window. An illumination control unit to be controlled and a brightness detection unit for subject information from the imaging unit are provided, and the illumination control unit is detected by the brightness detection unit when the illuminance of the illumination unit is changed. Since the illuminance of the illumination unit is set based on the amount of change in brightness of the subject information to be performed, an increase in temperature of the imaging window portion can be suppressed.

  That is, in the present invention, when the illumination control unit changes the illuminance of the subject from the illumination unit, the amount of change in brightness of the subject information detected by the brightness detection unit is determined. The magnitude of the amount of change makes it possible to estimate the degree of influence of the illuminance of the illumination unit on the subject, and the illuminance of the illumination unit can be reduced according to the degree of influence of the illumination. The temperature rise can be suppressed.

  Therefore, it is expected to be widely used as an intraoral camera.

DESCRIPTION OF SYMBOLS 1 Main body case 2 Code | symbol 3 Intraoral insertion part 3a Imaging window 4 Lens tube 4a Front side opening 4b Back side opening 5 Spacer cylinder 6 Spacer cylinder 7 Spacer cylinder 8 Prism 9 Illumination element 10 Focus unit 10a Focus lens part 10b Imaging part 11 Imaging Button 12 Image sensor 13 Focus lens cover holder 14 Focus lens front cover 15 Drive motor 16 Movable part 17 First guide pole 18 Second guide pole 19 Focus lens rear cover 20 Aperture 21 Lens part 22 Control part 23 Illumination part 24 Illumination control unit 27 Subject EV value 28 ΔEV
G1 lens group G2 lens group G3 lens group G4 lens group G5 lens group G6 lens group

Claims (6)

A main body case, and an intraoral insertion portion attached to the front side of the main body case;
An imaging window that optically captures a subject, disposed at the front opening of the intraoral insertion portion,
A lens unit optically coupled to the imaging window;
An imaging unit that captures optical subject information from the lens unit;
An illumination unit arranged around the imaging window,
An illumination control unit for controlling the illuminance of the illumination unit;
A brightness detection unit for subject information from the imaging unit; and
The intraoral camera configured to set the illuminance of the illuminating unit from the amount of change in brightness of the subject information detected by the brightness detecting unit when the illuminance of the illuminating unit is changed. A control unit that controls the aperture of the lens unit and the shutter speed of the imaging unit;
2. The intraoral cavity according to claim 1, wherein the subject information brightness detection unit is configured to detect the brightness of the subject information from an aperture value of the lens unit controlled by the control unit and a shutter speed of the imaging unit. camera. Means for measuring a subject distance from the imaging window to the subject;
The illumination control unit, when changing the illuminance of the subject from the illumination unit, the amount of change in the brightness of the subject information detected by the brightness detection means, the subject distance from the subject distance measurement unit, The intraoral camera according to claim 1, wherein the illuminance of the illumination unit is reset. The intraoral camera according to any one of claims 1 to 3, wherein the brightness of the subject information detected by the brightness detection means is an EV value. A method for controlling the illuminance of an illumination unit in an intraoral camera,
A first step of illuminating a subject with a predetermined illuminance;
A second step of capturing the subject information into the imaging unit;
A third step of detecting the brightness of the subject information captured by the imaging unit;
A fourth step of illuminating the illuminance with an illuminance that is a predetermined value lower than the illuminance in the first step;
A fifth step of detecting the brightness of the subject information captured by the imaging unit;
The brightness of the subject information in the third step and the sixth step of setting the illuminance of the illumination unit from the amount of change in the brightness of the subject information in the fifth step. Control method. 6. The intraoral camera according to claim 5, wherein a step of shifting to the first step is added as a pre-step of the first step when the subject distance from the imaging window to the subject is a predetermined distance or more. Lighting control method.

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