JP5866962B2 - Lighting device - Google Patents

Description

  The present invention relates to a lighting device.

  A lighting device used at the time of photographing with a camera generates a large amount of heat due to, for example, light emission or charging during continuous use. Therefore, a camera system that restricts the amount of flash emission during continuous light emission when the temperature of the flash light emitting device is equal to or higher than a threshold has been proposed (see Patent Document 1 as an example).

JP 2005-156793 A

  If the light emission of the lighting device is limited depending on whether or not the threshold temperature is exceeded, the behavior of the lighting device changes greatly before and after the threshold temperature, which is a control that gives the user a sense of discomfort.

An illumination device which is one embodiment of the present invention includes a light source unit that emits illumination light, a lens that transmits the illumination light, a temperature acquisition unit that acquires the temperature of the lens , and a control unit. The control unit gradually decreases the light emission amount limit value of the light source unit according to the elapsed time from the previous light emission of the light source unit. Further, the control unit changes the decrease rate of the light emission amount limit value with respect to the elapsed time according to the temperature.

  In the above aspect, the control unit may reduce the decrease rate in proportion to the temperature.

  In the above aspect, the control unit may determine a light emission amount limit value at the end of light emission of the light source unit according to the light emission amount of the light source unit in the previous light emission.

  The illumination device according to one aspect further includes an optical member that transmits illumination light from the light source unit, and a moving unit that changes a light distribution angle of the illumination light by adjusting a relative distance between the light source unit and the optical member. It may be. And a control part may change said reduction | decrease rate according to a relative distance.

  The lighting device according to one embodiment may further include a capacitor that accumulates electric charges output to the light source unit. And a control part may perform control which starts charge to a capacitor from the light emission end time of a light source part.

  According to one embodiment of the present invention, it is possible to perform light emission limitation in accordance with the temperature of the apparatus without causing a user a great sense of discomfort.

The perspective view which shows the outline | summary of the camera system containing the illuminating device of one Embodiment. The figure which shows the structural example of the illuminating device in one embodiment. Partial enlarged view of the head of the lighting device The flowchart which shows the operation example of the illuminating device in one embodiment. The figure which shows an example of the change by the elapsed time of the light emission amount limit value The figure which shows the state which brought the relative distance of the xenon tube and the Fresnel lens close from FIG. The figure which shows the state which kept the relative distance of a xenon tube and a Fresnel lens away from FIG. The figure which shows an example of the fluctuation history of light emission amount limit value

<Description of One Embodiment>
FIG. 1 is a perspective view illustrating an outline of a camera system including an illumination device according to an embodiment. A camera system 1 shown in FIG. 1 includes a camera body 2, an illumination device 3, and a lens barrel 4. The illumination device 3 and the lens barrel 4 are mounted on the camera body 2 in a replaceable manner. The camera body 2 captures an image of a subject formed by the lens of the lens barrel 4 with an image sensor (not shown).

  The illumination device 3 is a module that irradiates illumination light directly or indirectly to a subject during imaging. The illuminating device 3 includes a head unit 10 that emits illumination light, and a main body unit 11 that supports the head unit 10 and controls light emission and the like of the head unit 10. The head unit 10 of the illuminating device 3 is supported so as to be rotatable with respect to the main body 11 around a rotation axis extending in the X direction in the drawing. In addition, the illuminating device 3 of one Embodiment can change the irradiation angle of illumination light.

  The illuminating device 3 in one embodiment is attached to the accessory shoe 2 a of the camera body 2 by the mounting legs 12 provided at the lower part of the body portion 11. Each of the mounting legs 12 and the accessory shoe 2a is provided with a connection terminal (not shown). When the illumination device 3 is mounted on the camera body 2, an electrical connection is established between the connection terminals. As a result, information is transmitted between the camera body 2 and the illumination device 3. In addition, the illuminating device 3 in one Embodiment can also be functioned as a remote illuminating device which light-emits illumination light in the position away from the camera main body 2. FIG.

  FIG. 2 is a diagram illustrating a configuration example of a lighting device according to an embodiment. FIG. 3 is a partially enlarged view of the head portion of the illumination device. The illumination device 3 includes a xenon tube 21 that is an example of a light source unit, a main capacitor 22, a reflector 23, a reflector holder 24, a Fresnel lens 25 that is an example of an optical member, a first temperature sensor 26, and a moving unit. 27, a power supply unit 28 that supplies power to the lighting device 3, a light emitting circuit 29, a second temperature sensor 30, an operation unit 31, and a control unit 32.

  Here, the xenon tube 21, the main capacitor 22, the reflector 23, the reflector holder 24, the Fresnel lens 25, the first temperature sensor 26, and the moving unit 27 are accommodated in the head unit 10 of the lighting device 3. The power supply unit 28, the light emitting circuit 29, the second temperature sensor 30, the operation unit 31, and the control unit 32 are accommodated in the main body unit 11 of the lighting device 3. The control unit 32 is connected to the first temperature sensor 26, the moving unit 27, the power supply unit 28, the light emitting circuit 29, the second temperature sensor 30, the operation unit 31, and the connection terminals of the mounting legs 12.

  The xenon tube 21 is discharged when a high voltage is applied from the main capacitor 22 and emits illumination light (flash). The main capacitor 22 accumulates electric charges output to the xenon tube 21 and supplies power to the xenon tube 21 under the control of the light emitting circuit 29.

  The reflector 23 opens toward the front of the head unit 10 (the left side in FIGS. 2 and 3), and reflects the illumination light emitted from the xenon tube 21 toward the subject to be irradiated. In the longitudinal section of the reflector 23, the rear side of the head part 10 forms a parabolic or semicircular concave surface, and the xenon tube 21 is disposed at the focal point of the concave surface. The reflector 23 in one embodiment is formed by processing a metal thin plate, for example, and the surface of the reflector 23 facing the xenon tube 21 forms a reflecting surface.

  The reflector holder 24 is a resin member that holds the reflector 23. The left side of the reflector holder 24 in the figure corresponds to the shape of the reflector 23 and forms a holding surface for holding the reflector 23 from the back side. Further, on the back side (right side in the figure) of the holding surface of the reflector holder 24, a recessed portion 24a and a female screw portion 24b are formed. The female screw portion 24b of the reflector holder 24 is formed with a screw hole in the horizontal direction in the figure, and is screwed with a male screw (34) described later. The recess 24 a of the reflector holder 24 is a recess for arranging the first temperature sensor 26, and is formed at a position corresponding to the vertex of the concave surface of the reflector 23. Note that the thickness of the recessed portion 24 a of the reflector holder 24 is thinner than the portion other than the recessed portion 24 a of the reflector holder 24.

  The Fresnel lens 25 is, for example, a transparent or translucent resin lens provided with concentric Fresnel grooves. The Fresnel lens 25 is disposed in the direction of the subject with respect to the xenon tube 21 (left side in FIGS. 2 and 3). When the xenon tube 21 emits light, the Fresnel lens 25 transmits the direct light from the xenon tube 21 and the reflected light reflected by the reflector 23 to diffuse the illumination light to the outside.

  The first temperature sensor 26 is disposed on the back surface side of the reflecting surface of the reflector 23, and acquires the temperature in the vicinity of the xenon tube 21 across the reflector 23. Here, the first temperature sensor 26 in one embodiment is fixed and disposed in the recess 24 a of the reflector holder 24. Since the indentation 24a is formed at the apex of the concave surface of the reflector 23, the first temperature sensor 26 is the optical axis of the Fresnel lens 25 when viewed in the longitudinal section of the head 10 (FIGS. 2 and 3). It is arranged on a straight line passing through the center and the xenon tube 21.

  The moving unit 27 adjusts the relative distance between the xenon tube 21 and the Fresnel lens 25 to change the light distribution angle of the illumination light. The moving unit 27 includes a male screw 34 and a drive unit 35 that rotates the male screw 34. The male screw 34 extends in the optical axis direction (Y direction) of the Fresnel lens 25 and is screwed with the female screw portion 24 b of the reflector holder 24. When the male screw 34 is rotated by the drive unit 35, the reflector holder 24 moves in the Y direction. Thereby, the xenon tube 21 and the reflector 23 move along the Y direction, and the relative distance between the xenon tube 21 and the Fresnel lens 25 is adjusted. The drive unit 35 incorporates an encoder (not shown) that detects the amount of rotation of the male screw 34. The rotation amount of the male screw 34 detected by the encoder is used to obtain the position of the xenon tube 21 in the Y direction (the relative distance between the xenon tube 21 and the Fresnel lens 25).

  The light emitting circuit 29 includes a booster circuit that boosts the voltage of the power supply unit 28 to a predetermined charging voltage, and an output circuit that outputs the charge charged in the main capacitor 22 to the xenon tube 21 (both booster circuit and output circuit). Is omitted). The operation of the light emitting circuit 29 is controlled by the control unit 32.

  The second temperature sensor 30 is a temperature sensor for acquiring the environmental temperature around the device. The second temperature sensor 30 is disposed at a position away from the light source. As the first temperature sensor 26 and the second temperature sensor 30, a known temperature sensor such as a thermistor can be used.

  The operation unit 31 includes a power switch of the lighting device 3, a dial for setting a dimming mode and an illumination angle, a ready lamp (31a) that is turned on when a certain amount of charging is completed, and a liquid crystal panel that displays various types of information. A user interface. The operation unit 31 is disposed on the back surface (right side in FIG. 2) of the main body unit 11.

  The control unit 32 is a circuit that performs overall control of the lighting device 3. For example, the control unit 32 performs light emission control of the xenon tube 21 via the light emitting circuit 29. Further, the control unit 32 controls the moving unit 27 to change the irradiation angle of the illumination light. At this time, the control unit 32 may make the irradiation angle wide when the focal length of the lens barrel 4 is short, and narrow the irradiation angle when the focal length of the lens barrel 4 is long. Note that when the irradiation angle is set to a wide angle, the control unit 32 may shorten the relative distance between the xenon tube 21 and the Fresnel lens 25. Further, when the irradiation angle is narrowed, the control unit 32 may increase the relative distance between the xenon tube 21 and the Fresnel lens 25.

  Furthermore, the control part 32 has the temperature estimation part 33 which is an example of a temperature acquisition part. The temperature estimation unit 33 estimates the temperature of the Fresnel lens 25 using the outputs of the first temperature sensor 26, the second temperature sensor 30, and the encoder. Note that the control unit 32 limits the light emission amount of the lighting device 3 according to the temperature of the Fresnel lens 25 obtained by the temperature estimation unit 33 in order to suppress thermal deformation of the Fresnel lens 25 due to light emission of the xenon tube 21. (See FIG. 4).

  Here, the temperature gradient in the Fresnel lens 25 can be obtained from the temperature in the vicinity of the xenon tube 21 acquired by the first temperature sensor 26 and the environmental temperature acquired by the second temperature sensor 30. Further, the relative distance between the xenon tube 21 and the Fresnel lens 25 can be obtained using the output of the encoder. Various thermal conductivities, dimensions of the head unit 10 and the like are known in advance, and the energy directly irradiated as infrared rays from the xenon tube 21 can be calculated from the light emission amount of the illumination device 3 and the like. Therefore, it can be understood that the temperature estimation unit 33 can derive the temperature of the Fresnel lens 25 from a known heat conduction equation by using the above parameters.

  Next, an operation example of the illumination device according to the embodiment will be described with reference to the flowchart of FIG. Note that the processing of the flowchart of FIG. 4 is started by the control unit 32 when the power switch is turned on.

  Step # 101: The light emitting circuit 29 starts charging the main capacitor 22 under the control of the control unit 32. In one embodiment, the control unit 32 turns on the ready lamp 31a at a stage where half light emission is possible compared to full light emission.

  Step # 102: The control unit 32 determines whether or not a light emission signal instructing light emission is received from the camera body 2. If the above requirement is satisfied (YES side), the process proceeds to # 103. On the other hand, if the above requirement is not satisfied (NO side), the process proceeds to # 106.

  Step # 103: The light emitting circuit 29 causes the xenon tube 21 to emit light under the control of the control unit 32. Thereby, illumination light is irradiated to the subject.

  Step # 104: The light emitting circuit 29 resumes charging of the main capacitor 22 immediately after the light emission ends under the control of the control unit 32.

  Step # 105: The control unit 32 starts the control for limiting the light emission amount of the xenon tube 21 to the light emission amount limit value or less immediately after the light emission ends. Thereafter, the control unit 32 returns to # 102 and repeats the above operation.

  FIG. 5 is a diagram illustrating an example of a change in the light emission amount limit value depending on the elapsed time. The vertical axis in FIG. 5 represents the light emission amount limit value, and the horizontal axis in FIG. 5 represents time.

In one embodiment, the light emission amount control value (Evlim) is expressed by the number of stages of Ev values based on the light emission amount at the time of full light emission. When the light emission amount limit value is “n” (where n is a natural number), the light emission amount at the time of full light emission is limited by the n stages of the Ev value (light emission amount 1/2 ⁿ ). For example, when the light emission amount limit value is “0”, the light emission amount is not limited and full light emission is possible. When the light emission amount limit value is “1”, the light emission amount at the time of full light emission is limited by one stage of the Ev value, and the upper limit of the light emission amount is ½ of that at the time of full light emission. Each time the light emission amount limit value increases by 1, the upper limit of the light emission amount is further halved.

  The control unit 32 in # 105 gradually decreases the light emission amount limit value in accordance with the elapsed time from the previous light emission of the xenon tube 21. Thereby, the maximum light emission amount of the illumination device 3 is largely limited by the light emission amount limit value immediately after the light emission is completed. However, as the light emission amount limit value decreases with the elapsed time, the maximum light emission amount of the lighting device 3 gradually approaches the original state with the elapsed time. FIG. 5 shows an example in which the light emission amount limit value and the elapsed time are linearly proportional.

  The control unit 32 in # 105 changes the decrease rate of the light emission amount limit value with respect to the elapsed time, depending on the temperature of the overheated portion of the lighting device 3 (the temperature of the Fresnel lens 25 acquired from the temperature estimation unit 33). Let Specifically, when the temperature of the Fresnel lens 25 is low, the control unit 32 increases the decrease rate of the light emission amount limit value with respect to the elapsed time. On the other hand, when the temperature of the Fresnel lens 25 is high, the control unit 32 reduces the decrease rate of the light emission amount limit value with respect to the elapsed time.

In the example of FIG. 5, when the temperature of the Fresnel lens 25 has a relationship of T ₁ <T ₂ <T ₃ , the rate of decrease of the light emission amount limit value with respect to the elapsed time (the slope of the straight line in the figure) is the temperature T _1. Things are the largest. And the decreasing rate of the light emission amount limit value with respect to the elapsed time decreases in the order of temperatures T ₂ and T ₃ . That is, as the temperature of the Fresnel lens 25 is lower, the light emission amount limit value decreases in a shorter time, and the required time (ready time) from when the light emission ends until the ready lamp 31a is turned on also becomes shorter.

  In addition, the control unit 32 in # 105 determines a light emission amount limit value at the end of light emission of the xenon tube 21 according to the light emission amount of the previous light emission of the xenon tube 21. The control unit 32 increases the light emission amount limit value when the light emission amount of the previous light emission is large. On the other hand, when the light emission amount of the previous light emission is small, a large amount of electric power remains in the main capacitor 22, and therefore the control unit 32 decreases the light emission amount limit value accordingly.

  Further, the control unit 32 in # 105 changes the decrease rate of the light emission amount limit value with respect to the elapsed time according to the relative distance between the xenon tube 21 and the Fresnel lens 25 obtained from the output of the encoder.

  FIG. 6 is a diagram illustrating a state in which the relative distance between the xenon tube 21 and the Fresnel lens 25 is reduced from FIG. FIG. 7 is a diagram illustrating a state in which the relative distance between the xenon tube 21 and the Fresnel lens 25 is increased from FIG. When the relative distance between the xenon tube 21 and the Fresnel lens 25 is short (FIG. 6), the Fresnel lens 25 is more likely to overheat than in the case of FIG. Therefore, the control unit 32 lowers the decrease rate of the light emission amount limit value with respect to the elapsed time under the same temperature condition as compared with FIG. 5 (the slope of the straight line in the figure becomes smaller). On the other hand, when the relative distance between the xenon tube 21 and the Fresnel lens 25 is long (FIG. 7), the Fresnel lens 25 is less likely to overheat than in the case of FIG. Therefore, the control unit 32 increases the decrease rate of the light emission amount limit value with respect to the elapsed time under the same temperature condition as compared with FIG. 5 (the slope of the straight line in the figure increases).

Note that the control unit 32 of # 105 may obtain the light emission amount limit value Evlim at an arbitrary time t from the end of light emission by the following equation (1).
Evlim = Evlims− (3 / RDYT) t (1)
“Evlims” in the above equation (1) is a light emission amount limit value at the end of light emission determined according to the light emission amount of the previous light emission. If the previous light emission is full light emission, Evlims is “4”, and if the previous light emission is half the light emission amount of full light emission, Evlims is “3”. “RDYT” is a ready time that varies depending on the temperature of the Fresnel lens 25 and the like.

  FIG. 8 is a diagram illustrating an example of the fluctuation history of the light emission amount limit value. The vertical axis in FIG. 8 indicates the light emission amount limit value, and the horizontal axis in FIG. 8 indicates time. When the light emission amount of the illumination device 3 is large (first light emission), the change in the light emission amount limit amount Evlim immediately after the light emission becomes large. On the other hand, when the light emission amount of the illumination device 3 is small (second light emission), the change in the light emission amount limit amount Evlim immediately after the light emission is relatively small. Note that the rate of decrease of the light emission amount limiting amount Evlim in FIG. 8 can change at any time according to the temperature of the Fresnel lens 25 and the change in the relative distance between the xenon tube 21 and the Fresnel lens 25.

  Step # 106: The control unit 32 determines whether or not the power switch is turned off. If the above requirement is satisfied (YES side), the control unit 32 ends the process of the flowchart of FIG. On the other hand, if the above requirement is not satisfied (NO side), the control unit 32 returns to # 102 and repeats the above operation. This is the end of the description of FIG.

  Hereinafter, the effect in the illuminating device 3 of one Embodiment is described.

  The illuminating device 3 of one embodiment has a light emission amount limit value in accordance with the elapsed time from the previous light emission of the xenon tube 21 based on the relationship of the decrease rate determined by the temperature of the overheated part (Fresnel lens 25). (# 105). That is, as the elapsed time from the previous light emission is longer, the light emission amount is increased, and when the temperature of the overheated portion is high, the ready time is relatively increased. Therefore, it is possible to perform light emission control for protecting the overheated portion of the lighting device 3 without giving the user a sense of incongruity compared to control for stopping charging or prohibiting light emission when the temperature reaches a threshold temperature.

  Further, in the lighting device 3 of one embodiment, while performing the light emission control by the light emission amount limit value (# 105), the charging of the main capacitor 22 is resumed immediately after the light emission is finished (# 104). Therefore, charging is almost completed during the period when the light emission amount is limited by the light emission amount limit value. For example, when charging reaches a threshold temperature and charging is resumed when the temperature decreases. As compared with the above, the lighting device 3 can emit light quickly.

  In addition, when an external power source is used for the lighting device, it is relatively difficult to control charging. However, in one embodiment, since the light emission control is performed using the light emission amount limit value, comparison is made even when an external power source is applied. The light emission control for protecting the overheated portion of the lighting device 3 can be easily performed.

<Supplementary items of the embodiment>
(Supplement 1) Although the example of the illuminating device using a xenon tube for the light source unit has been described in the above embodiment, the illuminating device of the present invention may be an illuminating device using an LED for the light source unit.

  (Supplement 2) In the above embodiment, the example of the illumination device externally attached to the camera body has been described. However, the illumination device of the present invention may be incorporated in the camera.

  (Supplement 3) In the above embodiment, the example in which the light emission amount limit value is obtained in accordance with the temperature of the Fresnel lens has been described. However, the illumination device of the present invention has other overheated parts (for example, a booster circuit, a main capacitor, The light emission amount limit value may be obtained based on the temperature of the power supply unit or the like. In addition, the illuminating device of this invention may acquire the temperature of the overheated part of an apparatus directly with a temperature sensor.

  (Supplement 4) In the above-described embodiment, an example of a lighting device having a function of changing the irradiation angle of illumination light has been described. However, the present invention is naturally applicable to a lighting device that does not have the above function.

  (Supplement 5) In the above embodiment, the example in which the light emission amount limit value and the elapsed time are linearly proportional has been described. However, the proportional relationship between the light emission amount limit value and the elapsed time in the present invention is nonlinear. Also good. For example, the proportional relationship between the light emission amount limit value and the elapsed time may be determined using the charging characteristic curve of the main capacitor.

  From the above detailed description, features and advantages of the embodiments will become apparent. It is intended that the scope of the claims extend to the features and advantages of the embodiments as described above without departing from the spirit and scope of the right. Further, any person having ordinary knowledge in the technical field should be able to easily come up with any improvements and modifications, and there is no intention to limit the scope of the embodiments having the invention to those described above. It is also possible to use appropriate improvements and equivalents within the scope disclosed in.

DESCRIPTION OF SYMBOLS 1 ... Camera system, 2 ... Camera body, 2a ... Accessory shoe, 3 ... Illuminating device, 4 ... Lens barrel, 10 ... Head part, 11 ... Main part, 12 ... Mounting leg, 21 ... Xenon tube, 22 ... Main capacitor , 23 ... reflector, 24 ... reflector holder, 24a ... hollow part, 24b ... female screw part, 25 ... Fresnel lens, 26 ... first temperature sensor, 27 ... moving part, 28 ... power supply part, 29 ... light emitting circuit, 30 ... first 2 temperature sensors, 31 ... operation section, 31a ... ready lamp, 32 ... control section, 33 ... temperature estimation section, 34 ... male screw, 35 ... drive section

Claims (5)

A light source that emits illumination light;
A lens that transmits the illumination light;
A temperature acquisition unit for acquiring the temperature of the lens ;
A control unit that gradually reduces the light emission amount limit value of the light source unit according to the elapsed time from the previous light emission of the light source unit,
Wherein, in response to said temperature, the light emission amount limit value of the reduction rate lighting device Ru changing the relative said elapsed time. The lighting device according to claim 1.
Wherein, in proportion to the height of the temperature, the reduction rate smaller to that lighting device. The lighting device according to claim 1 or 2,
Wherein, in response to said light emission amount of the previous light emission of the light source unit, the light emission amount limit value lighting apparatus that determine the light-emitting end of the light source unit. In the illuminating device of any one of Claims 1-3,
An optical member that transmits illumination light from the light source unit;
A moving unit that adjusts a relative distance between the light source unit and the optical member to change a light distribution angle of the illumination light; and
Wherein, in response to the relative distance, the rate of decrease lighting device Ru changing the. In the illuminating device of any one of Claims 1-4,
A capacitor for accumulating charges to be output to the light source unit;
Wherein, the row UTeru illumination device control to start charging from the light emitting end of the light source unit to the capacitor.

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