Illumination device

An illumination device includes a first light source, a first optical member configured to transmit light emitted from the first light source, a second optical member placed between the first light source and the first optical member and configured to transmit light emitted from the first light source, an air-movement mechanism configured to move air suctioned from a first space as an internal space closer to the first light source than the second optical member is and including the first light source, to a second space as a space between the first and second optical members, and a second light source different from the first light source, wherein a member included in a flow path of the air-movement mechanism is thermally connected to the second light source.

BACKGROUND OF THE DISCLOSURE

Field of the Disclosure

The present disclosure relates to the heat dissipation structure of an illumination device.

Description of the Related Art

In recent years, flash devices (illumination devices) on which a light-emitting diode (LED) capable of continuously lighting up is mounted, for use in a video light for capturing a moving image, a modeling light for confirming an illumination effect, and a focusing light for adjusting the focus of an imaging apparatus increase. Such a flash device requires an LED having a high luminance and a large amount of light in any of the applications of a video light, a modeling light, and a focusing light. Thus, an important issue is how to treat heat generated when the LED emits light.

For example, Japanese Patent Application Laid-Open No. 2015-028524 discusses an illumination device that transfers heat generated in a light-emitting unit to a heat dissipation member and then releases the heat through a path formed by a housing to outside.

In the technique discussed in Japanese Patent Application Laid-Open No. 2015-028524, however, heat from an LED is released through the path formed by the housing to outside, while water and foreign substances may enter the housing through the path.

SUMMARY OF THE DISCLOSURE

According to an aspect of the present disclosure, an illumination device includes a first light source, a first optical member configured to transmit light emitted from the first light source, a second optical member placed between the first light source and the first optical member and configured to transmit light emitted from the first light source, an air-movement mechanism configured to move air suctioned from a first space as an internal space closer to the first light source than the second optical member is and including the first light source, to a second space as a space between the first and second optical members, and a second light source different from the first light source, wherein a member included in a flow path of the air-movement mechanism is thermally connected to the second light source.

Further features and aspects of the present disclosure will become apparent from the following description of example embodiments with reference to the attached drawings.

DESCRIPTION OF THE EMBODIMENTS

Example embodiments, features and aspects of the present disclosure will be described in detail below based on the attached drawings. In the drawings, similar members are designated by the same reference numbers, and are not redundantly described.

First, with reference toFIGS. 1A and 1B, a flash device100, which is an illumination device according to an example embodiment of the present disclosure, is described.FIGS. 1A and 1Bare external perspective views of the flash device100according to the present example embodiment.FIG. 1Ais a view of the flash device100from its front surface side where an acrylic panel101is placed.FIG. 1Bis a view of the flash device100from its back surface side (an operation unit side).

The flash device100includes two main sections, namely a light-emitting section100a(a first housing) and a control section100b(a second housing). The light-emitting section100aincludes a discharge tube102(a first light source) that illuminates an object, and light-emitting diode (LED) elements161(a second light source) capable of lighting up more continuously than the discharge tube102. Further, the light-emitting section100ahas a bounce function of pivotally moving relative to the control section100b, thereby changing the emission directions of light emitted from an acrylic panel101and an LED window164. The pivotal movement may be manually performed by a user holding the light-emitting section100a, or may be automatically performed by a motor (not illustrated). In the present example embodiment, the direction in which the light-emitting section100aand the control section100bare arranged is defined as the up-down direction of the flash device100, and the light-emitting section100aside is defined as an upper side. Then, the up-down direction in a reference state where the angle of the rotational movement of the light-emitting section100arelative to the control section100bis 0 degrees as illustrated inFIGS. 1A and 1Bis defined as the up-down direction of the light-emitting section100a.

The light-emitting section100amainly includes an upper cover103(a first cover), a lower cover104(a second cover), and a bounce case105having a cylindrical shape. Further, the upper cover103includes a wide panel cover106that accommodates a wide panel108that spreads the distribution of emitted light. The wide panel108is an optical member having light diffusibility for spreading light emitted from the acrylic panel101to a wider angle. The wide panel108is pulled out from the wide panel cover106when used, and is placed to cover a front surface of the acrylic panel101. Alternatively, a configuration may be employed in which, as an auxiliary optical member, a catchlight sheet is placed instead of the wide panel108so that when the emission direction of emitted light is directed upward (in a Y-direction), the catchlight sheet reflects the emitted light, thereby providing a catchlight effect to an object. Yet alternatively, a configuration may be employed in which both the wide panel108and the catchlight sheet are placed. In a joining portion of the upper cover103and the lower cover104, side rubber107is provided and functions as an anti-slip member when the user manually pivotally moves the light-emitting section100a.

The upper cover103and the lower cover104can pivotally move in the up-down direction (a ZY plane direction) relative to the bounce case105. The bounce case105can pivotally move in the horizontal direction (an XZ plane direction) relative to the control section100b. As described above, the light-emitting section100ais rotationally movable relative to the control section100band can change the emission directions of light from the discharge tube102and the LED elements161. The control section100bsupports the light-emitting section100aand controls the operation of the light-emitting section100a.

A rear cover109as an exterior member is provided on aback surface side of the control section100b. On the rear cover109, operation units such as a display unit110, a power switch111, an operation button112, and a dial113are placed and allow various function settings. A battery cover114is an openable and closable cover for loading power supply batteries125into the control section100b. In a bottom cover115as an exterior member on a lower surface side, a leg portion116is included that is a connection portion to be detachably attached to an accessory shoe of a camera as an imaging apparatus (not illustrated). A drip-proof cover117is attached around the leg portion116. The leg portion116can be fixed to the accessory shoe of the camera (not illustrated) by rotationally moving a lock lever118. A front cover119is an exterior member on a front surface side of the control section100b. In a center portion of the front cover119, a bulge portion119ais provided that protrudes forward from the front cover119. In the lower half of the bulge portion119a, an optical pulse communication light-receiving window120and an autofocus (AF) assist light-emitting window121that assists the adjustment of the focus of the camera when the luminance is low are placed. In a part of the optical pulse communication light-receiving window120, an external light modulation light-receiving sensor122is included so that the flash device100alone can also perform light modulation other than the light modulation of the camera (not illustrated). On the opposite side of the battery cover114of the control section100b, various terminal covers123are included. Within the various terminal covers123, an external power supply terminal, a bracket fixing screw, and a synchronization terminal are included. In joining portions of the exterior members, drip-proof packing (not illustrated) is included and has dust-proof and drip-proof performance together with the terminal covers123and the drip-proof cover117.

As described above, in the present example embodiment, the side where the bulge portion119aof the control section100bis provided is defined as a front surface side, the side where the display unit110and the various operation units are provided is defined as a back surface side, and the side where the leg portion116of the control section100bis provided is defined as a lower surface side. Then, inFIGS. 1A and 1B, an X-direction corresponds to the left-right direction of the control section100b, a Y-direction corresponds to the up-down direction of the control section100b, and a Z-direction corresponds to the front-back direction of the control section100b. Hereinafter, unless otherwise stated, the left-right direction, the up-down direction, and the front-back direction of the flash device100are equal to the left-right direction, the up-down direction, and the front-back direction, respectively, of the control section100b.

Next, with reference toFIGS. 2, 3, 4A, and 4B, the internal configuration of the control section100band the internal configurations of the light-emitting section100aand the bounce case105are described.FIG. 2is an exploded perspective view illustrating the inside of the control section100bfrom the front surface side when the front cover119and the bottom cover115are removed from the control section100b.FIG. 3is a cross-sectional view orthogonal to the left-right direction of the flash device100.

In the center within the control section100b, a battery case124is provided between a main substrate128and a sub substrate129. In a battery accommodation portion124aof the battery case124, the power supply batteries125(four AA size batteries in the present example embodiment) are accommodated in an approximately square-shaped arrangement. Alternatively, a chargeable and dischargeable lithium-ion secondary battery may be employed. Above the battery accommodation portion124a, a predetermined space region126is provided between the battery accommodation portion124aand a shaft portion105afor a left-right rotational movement (a rotational movement in the XZ plane) on a lower surface of the bounce case105that protrudes from the light-emitting section100a. The space region126is provided to accommodate a wire harness127in a loosened state. The wire harness127is connected to the main substrate128and the sub substrate129. At this time, if the wire harness127is connected in a strained state without a sufficient length, the wire harness127may receive a twisting force by the left-right pivotal movement of the light-emitting section100aand become disconnected. Thus, the wire harness127is accommodated with sufficient looseness so as not to be influenced by the left-right pivotal movement in the space region126.

On a back surface side, i.e., the rear cover109side, of the battery case124, the main substrate128including a digital circuit is placed. On the main substrate128, a central processing unit (CPU)130is mounted. On the main substrate128, switch elements corresponding to the various operation members such as the power switch111placed on the rear cover109are also mounted. Inside the display unit110, a liquid crystal display (LCD)131is placed. On a front surface side and a lower surface side of the battery case124, a step-up circuit board133including a step-up transformer132and the sub substrate129having a light emission control circuit including a field-effect transistor (FET) (not illustrated) are attached.

On the front surface side of the battery case124, a pedestal134and the sub substrate129are attached one on top of the other. On a front surface side of the pedestal134, a wireless module135is attached by a plurality of engaging claws134aintegrally formed with the pedestal134. On an upper end side of the wireless module135, a wireless communication antenna135a(a chip antenna) is mounted. To a connector (not illustrated) on a lower end side of the wireless module135, a flexible substrate (not illustrated) linked to the main substrate128is connected. At a position opposed to the optical pulse communication light-receiving window120provided in a lower portion of the front cover119, an optical pulse light-receiving sensor136is placed. Further, at positions opposed to the AF assist light-emitting window121across a prism137, AF assist light units138are placed. The prism137divides a single pattern emitted from the AF assist light units138into a plurality of rays, and the AF assist light-emitting window121projects the plurality of rays (three AF assist light units138are provided in the present example embodiment). If the LED elements161can be used as a focusing light, the AF assist light units138do not need to be included.

To a back surface (the bounce case105side) of a hood142, a head substrate148connected to the discharge tube102is attached. Wiring lines (not illustrated) connected to the head substrate148are guided to a capacitor accommodation portion105bthrough a rotating portion149between the upper cover103that rotates about the center of the cylinder of the bounce case105, and the bounce case105. These wiring lines form the wire harness127with wiring lines connected to a capacitor147. The wire harness127is pulled out of the light-emitting section100afrom a hole portion105cformed in the center of the shaft portion105a. To the end of the wire harness127, a connector (not illustrated) is attached. This connector electrically connects circuits on the head substrate148provided within the light-emitting section100ato the main substrate128and the sub substrate129provided within the control section100b. As described above, the wire harness127electrically connects electronic components such as the discharge tube102and the capacitor147provided in the light-emitting section100ato the control substrates provided in the control section100b. To the end of the shaft portion105aof the bounce case105, a rotating plate150is attached. The rotating plate150has the function of restricting the left-right pivoting of the light-emitting section100ato a predetermined angle. The rotating plate150also has the function of preventing the light-emitting section100afrom coming out of the control section100b.

In the capacitor accommodation portion105bwithin the bounce case105having a cylindrical shape, the capacitor147(a main capacitor) is placed. That is, the capacitor147is placed on a rotational axis about which the light-emitting section100ais rotationally moved in the up-down direction (the Y-direction) relative to the control section100b. The capacitor147is placed near a connection portion of the light-emitting section100aand the control section100b. The capacitor147accumulates charges for causing the discharge tube102to emit light. With the accumulated charges, a high voltage required for the discharge tube102to emit light is generated.

By applying a trigger voltage from a trigger coil151to the discharge tube102, the discharge tube102starts discharging and emits light. The trigger coil151is mounted on the head substrate148and electrically connected to a reflective umbrella146by a trigger cable (not illustrated). The trigger voltage is applied from the trigger coil151through the reflective umbrella146to the discharge tube102. On the head substrate148, components regarding light emission, such as the trigger coil151and a choke coil152included in a light-emitting circuit, are mounted. On the head substrate148, a connector153is also mounted to which the wire harness127is connected. The choke coil152is electrically connected to the capacitor147and the discharge tube102between the capacitor147and the discharge tube102and dampens a current supplied from the capacitor147to the discharge tube102. This enables light emission control when flat light emission is performed, and also reduces an electrical load acting on the discharge tube102. On the light-emitting circuit, only the minimum components for causing the discharge tube102to emit light need to be mounted, and not all the above components need to be mounted.

FIGS. 4A and 4Bare exploded perspective views illustrating the inside of the light-emitting section100awhen the upper cover103and the lower cover104are removed from the light-emitting section100a.FIG. 4Ais a view of the light-emitting section100afrom its upper surface side.FIG. 4Bis a view of the light-emitting section100aits the lower surface side.

The flash device100according to the present example embodiment includes a driving mechanism for changing the emission angle of a Fresnel lens140as a first optical member within the acrylic panel101, and the discharge tube102by changing the relative position of the discharge tube102in the direction of the emission optical axis of the discharge tube102. The Fresnel lens140is an optical lens that refracts light emitted from the discharge tube102and transmits the light, thereby changing the distribution of the light. The acrylic panel101has the function of adjusting the distribution of the light emitted from the Fresnel lens140, adjusting the color temperature of the light, and protecting the Fresnel lens140from external contact (including shock and thermal protection). The present example embodiment is described using an optical system having a two-component configuration including the acrylic panel101and the Fresnel lens140. Alternatively, an optical system having a single-component configuration may be obtained by adding the function of the acrylic panel101to the Fresnel lens140. A light-emitting section unit139included in the driving mechanism accounts for a large portion of the inside of the light-emitting section100a. To an upper surface of the hood142as a structure of the light-emitting section unit139, a motor unit144including a lead screw143as an actuator is attached. To a reflective umbrella holder145, the discharge tube102, the reflective umbrella146that reflects light forward from the discharge tube102, and front glass154that blocks heat transferred from the discharge tube102to the Fresnel lens140are attached. The reflective umbrella146covers from an upper side through a back side to a lower side of the discharge tube102and reflects light emitted backward and in the up-down direction from the discharge tube102, toward the Fresnel lens140. The reflective umbrella holder145changes the relative distance between the Fresnel lens140and the discharge tube102in conjunction with the rotation of the lead screw143. This changes the light distribution angle of emitted light. In the present example embodiment, a flash device having a configuration in which the light distribution angle of emitted light is changed by changing the distances from the discharge tube102and the reflective umbrella146to the Fresnel lens140is used. Alternatively, a configuration may be employed in which the light distribution angle of emitted light is changed by changing the distance between upper and lower reflective surfaces of the reflective umbrella146. In a case where light is not reflected in the emission direction of the light-emitting section unit139by the reflective umbrella146, the hood142diffusely reflects the light in the emission direction of the light-emitting section unit139. Thus, to efficiently reflect light in the emission direction of the light-emitting section unit139, the hood142has such a shape that the closer to the Fresnel lens140an opening on a plane orthogonal to the optical axis of light emitted from the light-emitting section unit139is, the larger the opening is. As described above, the hood142can be said to be a reflective member that surrounds the discharge tube102with an opening in a part of the reflective member and reflects a part of light emitted from the discharge tube102in the direction of the opening.

Fresnel protective glass141as a second optical member is placed between the discharge tube102and the Fresnel lens140with a predetermined space from the Fresnel lens140and transmits light emitted from the discharge tube102. This protects the Fresnel lens140from the heat of the discharge tube102generated by light emission and also forms a flow path156that allows air from a blower fan155to pass. Incidentally, the front glass154also has a function similar to that of the Fresnel protective glass141in that the Fresnel lens140is protected by blocking heat transferred from the discharge tube102to the Fresnel lens140. The front glass154, however, keeps heat from the discharge tube102near the front glass154by the front glass154and the reflective umbrella holder145and therefore is likely to apply a thermal load to the discharge tube102. To dissipate more heat from the discharge tube102, the front glass154may not be provided.

The blower fan155is placed in a fan accommodation portion104aof the lower cover104and thermally connected to the lower cover104. The blower fan155is electrically connected to the head substrate148by a wire harness (not illustrated). The blower fan155is driven by the CPU130of the control section100bcontrolling the rotation of the blower fan155based on a pulse-width modulation (PWM) signal via the head substrate148. An air intake portion155aof the blower fan155faces the light-emitting section unit139side and takes in air heated by the discharge tube102. Then, the air passes through the flow path156formed by the Fresnel lens140and the Fresnel protective glass141via a flow path component member160that bends exhaust air from the blower fan155in a direction approximately orthogonal to the optical axis of the discharge tube102, thereby cooling the Fresnel lens140. The air that has come out of the flow path156is bent to the motor unit144side and discharged and flows into the light-emitting section unit139.

That is, the blower fan155functions as a air-movement mechanism for sending air suctioned from a first space as an internal space closer to the first light source than the second optical member is and including the first light source, to a second space as a space between the first and second optical members.

Next, with reference toFIGS. 5A and 5B, the configuration of an LED light unit165is described.FIGS. 5A and 5Bare perspective views illustrating the configurations of the blower fan155and the LED light unit165. To the fan accommodation portion104aof the lower cover104, the blower fan155is fixed via an elastic member (not illustrated) to absorb vibration. The blower fan155is thermally connected to the lower cover104. To an air exhaust portion155bof the blower fan155, the flow path component member160is attached. At a position outside the flow path of the flow path component member160, an LED fixing portion160ais provided. To the LED fixing portion160aof the flow path component member160, an LED substrate162on which the LED elements161are mounted is fixed with a screw (not illustrated) or bonded with an elastic member (not illustrated). Heat generated with the light emission of the LED elements161is transferred via the LED fixing portion160ato the flow path component member160. A connection portion160bis thermally connected to the blower fan155via an elastic member (not illustrated). In the flow path component member160, standing walls160care provided to efficiently hit exhaust air from the blower fan155against a portion of the Fresnel lens140that receives heat from the discharge tube102.

The LED substrate162is a substrate composed of a metal such as aluminum to enhance heat conductivity. The LED substrate162, however, may be composed of a material other than a metal or composed of a composite material of a metal and another material so long as desired heat conductivity is obtained. Heat generated with the light emission of the LED elements161is transferred via the LED substrate162to the flow path component member160. The flow path component member160is molded from a metal such as aluminum or another material and efficiently diffuses the heat from the LED elements161to the entirety of the flow path component member160. The diffused heat is conducted from the flow path component member connection portion160bto the blower fan155and transferred to the lower cover104via an elastic member (not illustrated). The lower cover104is in contact with external air and therefore can dissipate the transferred heat to the external air. Since exhaust air from the blower fan155passes through the flow path component member160, the flow path component member160is forcibly cooled by the blower fan155. Thus, it is possible to prevent an excessive rise in the temperature of the LED elements161. The standing walls160cof the flow path component member160also contribute to increasing the surface area that exhaust air from the blower fan155hits to forcibly cool heat from the LED elements161. Between the standing walls160con both sides (within the flow path156), cooling fins160dmay be provided that extend in a direction parallel to the air-movement direction to enhance the cooling effect by increasing the surface area.

In front of the LED elements161, LED lenses163are placed that control the distribution of light beams emitted from the LED elements161. Further, in front of the LED lenses163, the LED window164is placed. Alternatively, the LED lenses163may be covered by the acrylic panel101without using the LED window164.

Next, with reference toFIG. 6, the cooling structure of the light-emitting section100aaccording to the present example embodiment is described.FIG. 6is a cross-sectional view illustrating the flow of main air in the light-emitting section100a. Arrows inFIG. 6indicate the direction in which main air flows.

As described above, the blower fan155is thermally connected to the lower cover104. When taking in air warmed up by the discharge tube102, the blower fan155transfers heat to the lower cover104, thereby cooling down the taken-in air. The lower cover104is in contact with external air and therefore can efficiently cool down the taken-in air while dissipating the transferred heat to the external air. A fan driving substrate (not illustrated) is electrically connected to the head substrate148in the light-emitting section100aby a wire harness (not illustrated) and the blower fan155is driven by supplying power and based on a driving control signal. Blades155drotate at high speed, whereby the blower fan155takes in air heated by the light emission of the discharge tube102from the air intake portion155a. Then, the blower fan155increases the flow rate of the air and sends the air from the air exhaust portion (blast port)155b. The longitudinal direction of the air exhaust portion155band the longitudinal direction of the discharge tube102are the same, whereby it is possible to efficiently send air to a region in the Fresnel lens140where the temperature is likely to rise due to the influence of the discharge tube102.

Exhaust air from the blower fan155passes through the flow path156formed by the Fresnel lens140and the Fresnel protective glass141, via the flow path component member160. When the air passes through the flow path156, the air is allowed to pass in the state where the flow rate of the air is maintained, whereby it is possible to effectively cool the Fresnel lens140, the temperature of which has risen due to heat generated with the light emission of the discharge tube102.

Even if the blower fan155takes in air heated by the light emission of the discharge tube102, the lower cover104can dissipate heat as described above. The Fresnel lens140heated by the heat and the light of the discharge tube102is much higher in temperature than air sent from the blower fan155. Thus, the temperature difference required to cool the Fresnel lens140is sufficiently large, and the Fresnel lens140can be cooled. The flow path component member160bends the flow of air sent from the blower fan155in an approximately orthogonal direction, whereby it is possible to make the entire configuration of the light-emitting section100asmall while forming the flow path156in a direction orthogonal to the longitudinal direction of the discharge tube102.

Air that has flowed out of the flow path156flows into an outflow path103awhile smoothly changing its moving direction from the up direction (the Y-direction) to the back direction (the Z-direction) with an outflow port103eformed in the upper cover103. The air that has flowed into the outflow path103apasses within the hood142and is taken in by the blower fan155while drawing in heat from the discharge tube102again.

Even if light is continuously emitted by cooling the discharge tube102, the LED elements161, and the Fresnel lens140while circulating air within the flash device100as described above, it is possible to protect the discharge tube102and the Fresnel lens140. Further, the blower fan155that cools the discharge tube102can simultaneously cool heat from the LED elements161using the flow path component member160as a heat sink. Thus, since a heat sink dedicated to the cooling of the LED elements161does not need to be separately used, it is possible to reduce the number of components. Further, in the above configuration, air is circulated within a closed space. Thus, this configuration can be achieved while maintaining dust-proof and drip-proof performance. In the present example embodiment, a description has been given of an example of a configuration in which air is circulated within the flash device100using the blower fan155. Alternatively, a mechanism for circulating air within the flash device100may use another fan or a pump.

As described above, according to the present example embodiment, in the flash device100, it is possible to protect the discharge tube102, the LED elements161, and the Fresnel lens140from heat generated by the light emission of the discharge tube102and the LED elements161.

The above example embodiments are merely typical examples and can be modified and changed in various manners when the present disclosure is carried out. For example, a configuration may be employed in which a light source different from the discharge tube102or the LED elements161is used in a video light, a modeling light, or a focusing light.

This application claims the benefit of Japanese Patent Application No. 2019-093735, filed May 17, 2019, which is hereby incorporated by reference herein in its entirety.