JP2014135241A - Illumination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination device having a simple configuration capable of stably irradiating illumination light and also capable of irradiating the illumination light immediately after drive start even under low temperature environment.SOLUTION: An illumination device A includes: a supply circuit 4 for supplying DC power; a first circuit 1 for supplying a constant current to a light source 3; a second circuit for supplying voltage from the supply circuit 4 to the light source 3; and a switcher 5 for connecting the supply circuit 4 to one of the first circuit 1 and the second circuit 2. When a temperature of an element included in the first circuit 1 is lower than a predetermined set temperature, the switcher 5 connects the supply circuit 4 to the second circuit 2.

Description

  The present invention relates to an illumination device that turns on a light source.

  Light emitting diodes (LEDs) have advantages such as shorter time to lighting (immediate lighting), small size and light weight, and less emission of ultraviolet rays compared to fluorescent lamps. The lighting device including the LED lamp includes elements such as a switching element, a coil, and a smoothing capacitor, and includes a circuit (for example, a DC / DC converter) that supplies direct current. In such an illuminating device, an operation limit temperature is often determined in order to guarantee a stable operation of the circuit that supplies the direct current.

  On the other hand, since the LED has the above-described characteristics, it is frequently used in a warehouse or the like, and is increasingly used in a freezer warehouse for storing food or the like. The frozen warehouse is often in a low temperature environment (referred to as a cryogenic environment) lower than the lower limit of the operation limit temperature. Under such an extremely low temperature environment, the ability of the coil may be reduced or the coil may not operate stably. As described above, when the coil does not operate correctly, the power supplied to the LED lamp becomes unstable, and the lighting of the LED lamp becomes unstable or does not light.

  In view of this, the LED-equipped electric circuit board for illumination disclosed in Japanese Patent Application Laid-Open No. 2011-254796 uses a lighting device equipped with an LED lamp in a temperature environment equal to or lower than the above-described operating temperature limit. There is an electric heater for heating the electric circuit board.

  In such an illumination LED-mounted electric circuit board, the electric heater heats the electric circuit board, that is, a circuit (element) whose operation in a low-temperature environment is difficult to stabilize to an operating limit temperature or higher. Thereby, the direct current with high accuracy can be supplied to the LED, and the LED lamp can be stably lit.

JP 2011-254796 A

  However, in the configuration described in Japanese Patent Application Laid-Open No. 2011-254796, an electric heater for heating the circuit board is required, the configuration becomes complicated, and electric power for driving the electric heater is required. Power consumption will increase.

  Further, in order to heat the circuit board to the operation limit temperature or more with the electric heater, a certain time is required, and the LED is not turned on during that time. Therefore, in such a lighting device, the LED lamp cannot be turned on immediately, which is not convenient.

  Accordingly, an object of the present invention is to provide an illuminating device that has a simple configuration and can irradiate illumination light stably and can irradiate illumination light immediately after the start of driving even in a low temperature environment.

  In order to achieve the above object, the present invention provides a supply circuit for supplying DC power, a first circuit for converting power from the supply circuit and supplying a constant current to a light source, and supplying power from the supply circuit to the light source. A lighting device comprising: a second circuit that supplies the first circuit; and a switch that connects the supply circuit to either the first circuit or the second circuit. When the temperature of an element included in the circuit is lower than a predetermined set temperature, the lighting device is characterized in that the supply circuit is connected to the second circuit.

  According to this configuration, while the operation of the element included in the first circuit is unstable, power is supplied to the light source using the second circuit, and after the element is heated to a stable level, a constant current is supplied. The first circuit that can supply the power is used. Thereby, it is possible to immediately turn on the conventional lighting device that does not supply power to the light source until the element stably operates by using the second circuit. In addition, after the element can be stably operated, the first circuit that outputs a constant current is used, so that flickering of illumination can be suppressed.

  According to the present invention, it is possible to provide an illuminating device that has a simple configuration and can irradiate illumination light stably and can irradiate illumination light immediately after the start of driving even in a low temperature environment.

It is a circuit diagram of an example of the illuminating device concerning this invention. It is sectional drawing of an example of the illuminating device concerning this invention. It is a figure which shows the temperature of a switch, the input current to a switch, and the supply current to a LED lamp. It is a figure which shows operation | movement of the other example of the illuminating device concerning this invention. It is a circuit diagram of the further another example of the illuminating device concerning this invention. It is a flowchart which shows operation | movement of the illuminating device shown in FIG.

Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
FIG. 1 is a circuit diagram of an example of a lighting device according to the present invention, and FIG. 2 is a cross-sectional view of an example of a lighting device according to the present invention. The illumination device A shown in FIG. 1 includes a first circuit 1, a second circuit 2, an LED lamp 3, a rectifier circuit 4, and a switch 5.

  The illuminating device A is supplied with AC power from an external AC power supply Ps, and uses the rectifier circuit 4 to rectify AC to DC. The rectifier circuit 4 is a circuit that converts alternating current into direct current (pulsating flow), and is used as a supply circuit that supplies electric power. In the lighting device A, a diode bridge that performs full-wave rectification is used as the rectifier circuit 4, but is not limited thereto.

  The rectifier circuit 4 includes a high voltage side terminal and a low voltage side terminal. As shown in FIG. 1, the terminal on the low voltage side is grounded. Therefore, in the rectifier circuit 4 of the lighting device A, the low voltage side terminal is a minus terminal and the high voltage side terminal is a plus terminal. The high voltage side terminal is connected to the switch 5, and the direct current (input current) rectified by the rectifier circuit 4 from the high voltage side terminal is input to the switch 5.

  The switch 5 has one input contact 50, two output contacts (first output contact 51, second output contact 52), and a switching piece 53. The input contact 50 of the switch 5 is connected to the high voltage side terminal of the rectifier circuit 4. The first output contact 51 is connected to the first circuit 1 (here, a switching element 11 described later), and the second output contact 52 is connected to the second circuit 2 (here, a resistor 21 described later). Is done.

  One end of the switching piece 53 is fixed to the input contact 50. The switching piece 53 is a member having a bimetal obtained by bonding members having different linear expansion coefficients, and has conductivity. The switching piece 53 has a different deformation direction depending on the temperature, and the other end of the switching piece 53 is in contact with either the first output contact 51 or the second output contact 52 in a conductive manner. The switch 5 is a so-called temperature switch that brings the input contact 50 and the first output contact 51 or the second output contact 52 into a conductive state depending on the temperature.

  As shown in FIG. 1, both the first circuit 1 and the second circuit 2 are connected to the positive terminal of the LED lamp 3, and both supply current (supply current) to the LED lamp 3. Details of each circuit will be described later. In the illumination device A, the LED lamp 3 is a lamp in which a plurality of LEDs (light sources) are connected in series. The LED is an element that is turned on at the same time as being energized (immediately turned on), and the LED lamp 3 is also a lamp that can be turned on immediately. In addition, although it is assumed that a plurality of LEDs are connected in series as the LED lamp 3, the present invention is not limited to this, and the LED lamp 3 has a configuration in which an LED group in which a plurality of LEDs are connected in series is connected in parallel. There may be.

  The first circuit 1 is a conversion circuit (DC / DC converter) that converts a direct current (pulsating flow) output from the rectifier circuit 4 into a current that can light the LED lamp 3 stably. As shown in FIG. 1, the first circuit 1 includes a switching element 11, a coil 12, a smoothing capacitor 13, a diode 14, and a switching driver 15.

  In the first circuit 1, an n-type MOSFET is used as the switching element 11. However, the present invention is not limited to this, and elements that can perform a switching operation (for example, bipolar transistors, IGBTs, etc.) are widely used. It is possible.

  As shown in FIG. 1, in the first circuit 1, a switching element 11 and a coil 12 are connected in series. The switching element 11 has a drain connected to the first output contact 51 of the switch 5 and a source connected to the coil 12. The cathode of the diode 14 is connected to the connection point between the switching element 11 and the coil 12.

  The gate of the switching element 11 is connected to the switching driver 15. A switching control signal (for example, a PWM signal) from the switching driver 15 is input to the gate of the switching element 11. The switching control signal is a pulse signal having a high level or a low level. In the switching element 11, when the switching control signal is at a high level, a current (electricity) flows between the drain and the source (turns ON). On the other hand, when the switching control signal is at the low level, no current (electricity) flows between the drain and source in the switching element 11 (turns OFF). The switching element 11 is ON / OFF controlled based on a switching control signal from the switching driver 15.

  The contact on the opposite side (output side) of the coil 12 to the switching element 11 is connected to the positive terminal of the LED lamp 3. The negative terminal of the LED lamp 3 is connected to the low voltage side terminal (minus terminal) of the rectifier circuit 4.

  The smoothing capacitor 13 is connected in parallel with the LED lamp 3. That is, one terminal of the smoothing capacitor 13 is connected to a wiring connecting the output side of the coil 12 and the positive terminal of the LED lamp 3, and the other terminal is a low voltage of the negative terminal of the LED lamp 3 and the rectifier circuit 4. It is connected to the wiring that connects the terminal on the side. The smoothing capacitor 13 is an element that can remove the pulsation component (ripple) of the supply current output from the coil 12.

  The anode of the diode 14 is connected to a portion closer to the rectifier circuit 4 than the connection point between the capacitor 3 of the wiring connecting the negative electrode terminal of the LED lamp 3 and the low voltage side terminal of the rectifier circuit 4.

  In the first circuit 1, the input current from the rectifier circuit 4 flows when the switching element 11 is ON. At this time, since the cathode side of the diode 14 is at a higher voltage (reverse voltage state) than the anode side, no current flows through the diode 14. The current that has passed through the switching element 11 passes through the coil 12 and flows toward the LED lamp 3. Energy is stored in the coil 12 by the input current from the rectifier circuit 4.

  When the switching element 11 is turned off, the input current from the rectifier circuit 4 is blocked by the switching element 11. Thereby, the reverse voltage state is eliminated and the diode 14 becomes conductive. Further, when the switching element 11 is turned off, no current is supplied to the coil 12, so the coil 12 releases the accumulated energy toward the LED lamp 3 as a supply current. The current emitted from the LED lamp 3 passes through the diode 14 and returns to the coil 12.

  In the first circuit 1, by repeating ON / OFF of the switching element 11, the above current flow is repeated, and the voltage of the input current from the rectifier circuit 4 is lowered (stepped down). In the first circuit 1, the smoothing capacitor 13 is further used to supply the LED lamp 3 with a supply current from which ripple is removed or reduced (smooth).

  When a smooth supply current is supplied from the first circuit 1, the LED lamp 3 is lit with a constant luminance. The smoothed direct current is not easily affected by disturbances such as noise, and from this, it is possible to suppress variations in luminance of the LED lamp 3, lighting failure, and the like. The current value (voltage value) of the supply current supplied to the LED lamp 3 can be determined by the operating frequency of the switching element 11 and the ratio of the ON time. Therefore, the first circuit 1 can adjust the current value of the supply current and adjust the brightness of the LED lamp 3 (dimming).

  The illuminating device A provided with the LED lamp 3 is also used in a freezing warehouse that stores articles such as food and medicines in a low temperature environment. In some freezing warehouses, the internal temperature is set to an extremely low temperature (for example, 60 ° C. or less below freezing point, referred to as a cryogenic environment) in order to suppress deterioration of articles and chemical reaction.

  The first circuit 1 uses elements such as the coil 12 and the smoothing capacitor 13 that have a lower temperature limit of about 40 ° C. below the freezing point, such as the above-described freezing warehouse. It may be difficult to operate stably in a very low temperature environment. Therefore, when the first circuit 1 including such an element is driven in a cryogenic environment, the LED lamp 3 may not be turned on immediately or the luminance may vary, which may cause a deterioration in the quality of the lighting device A. is there.

  Therefore, as shown in FIG. 1, the lighting device A of the present invention includes a second circuit 2 arranged in parallel with the first circuit 1 (in other words, bypassing the first circuit 1). In the lighting device A, the switching device 5 is configured to flow the input current rectified by the rectifier circuit 4 to either the first circuit 1 or the second circuit 2. Two output contacts 52 are connected.

The second circuit 2 includes a resistor 21. One terminal of the resistor 21 is connected to the second output contact 52 of the switch 5 and the other terminal is connected to the positive terminal of the LED lamp 3. That is, the second output contact 52 and the LED lamp 3 are connected via the resistor 21. The resistor 21 is a resistor for preventing the maximum value of the input current (voltage) from the rectifier circuit 4 from exceeding the current value (voltage value) allowed by the LED lamp 3. That is, the resistor 21 suppresses an overcurrent from flowing through the LED lamp 3 (an overvoltage is applied), and suppresses deterioration and breakage of the LED lamp 3. The resistor 21 is an element that is stable in operation even in a cryogenic environment. Thus, the second circuit 2 can perform a stable operation even in a cryogenic environment. In addition, when the input current (voltage) from the rectifier circuit 4 falls within the rating of the LED lamp 3, the resistor 21 may be omitted.

  The switch 5 is a temperature switch as described above. When the temperature of the switching device 5 (here, the switching piece 53) is equal to or lower than the set temperature, the switching piece 53 is in contact with the second output contact 52, and when the temperature is higher than the set temperature, the switching piece 53 is the first. Contact the output contact 51. That is, in the lighting device A, the supply current is supplied to the LED lamp 3 via the second circuit 2 when the temperature is lower than the set temperature, and the supply current is supplied to the LED lamp 3 via the first circuit 1 when higher than the set temperature. It is the structure supplied to.

  Here, the structure of the illumination device A will be described. As shown in FIG. 2, the illuminating device A includes a substrate Bd and a case Ca that covers the entire device. The LED lamp 3 is mounted on one surface of the substrate Bd, and the first circuit 1, the second circuit 2, and the switch 5 are provided on the other surface. And the board | substrate Bd with which the LED lamp 3, the 1st circuit 1, and the 2nd circuit 2 were mounted is covered by case Ca which has heat insulation. In addition, the part facing the LED lamp 3 of the case Ca has translucency so that the light emitted from the LED lamp 3 can be transmitted.

  Thus, the LED lamp 3 and the first circuit 1 are mounted close to the board Bd (here, on the back and front of the board Bd), so that the first circuit is heated by the heat when the LED lamp 3 is lit. 1 (an element that is difficult to operate stably in a low temperature environment) and the switch 5 can be heated. The substrate Bd is formed of a metal plate (here, aluminum) having a high thermal conductivity. However, the present invention is not limited to this, and members having high thermal conductivity can be widely used. Since the first circuit 1 and the switch 5 are heated by the heat generated by the LED lamp 3, a member such as a heater is unnecessary, the lighting device can be reduced, and the power consumption of the lighting device can be suppressed. it can.

  The operation of the illumination device A will be described with reference to the drawings. FIG. 3 is a diagram showing the temperature of the switch, the input current to the switch, and the current supplied to the LED lamp. In FIG. 3, the horizontal axis represents time. In FIG. 3, the top stage shows the temperature change of the switching unit 5, and the next stage is a contact point (the first output contact 51 or the second output) where the switching piece 53 of the switching unit 5 is in contact. A contact 52) is shown. The lower two stages show the current values of the input current and the supply current. As shown in FIG. 3, the input current is a pulsating current obtained by full-wave rectification of alternating current.

  The switch 5 has a configuration in which the contact point with which the switching piece 53 contacts is switched at the set temperature T. The set temperature T is the temperature of the switch 5 (here, the switching piece 53). Therefore, the set temperature T is the lowest temperature at which the elements included in the first circuit 1 operate stably (sometimes referred to as stable operation of the first circuit 1 in the following description) in the configuration of the lighting device A. The temperature of the switch 5 is determined to be higher or higher than that temperature.

  When the temperature t of the switch 5 is equal to or lower than the set temperature T, the temperature is lower than the lowest temperature at which the first circuit 1 operates stably. As shown in FIG. 3, in a region where the temperature t of the switch 5 is equal to or lower than the set temperature T, the switching piece 53 comes into contact with the second output contact 52, and the input contact 50 becomes conductive with the second output contact 52. At this time, the input current from the rectifier circuit 4 flows to the second circuit 2. Although the second circuit 2 includes the resistor 21, the resistor 21 is not an element that does not easily operate stably in an extremely low temperature environment. The resistor 21 passes through the resistor 21, and the stepped-down current is supplied as a supply current. To be supplied. As a result, the LED lamp 3 is turned on immediately.

  As shown in FIG. 2, the first circuit 1 and the switch 5 are disposed in the vicinity of the same substrate Bd as the LED lamp 3. Therefore, the 1st circuit 1 and the switch 5 are heated by the heat at the time of lighting of the LED lamp 3 (refer FIG. 3). In addition, since the case Ca has a heat insulating property, the first circuit 1 and the switching device 5 are effectively warmed because heat is difficult to escape.

  As shown in FIG. 3, the temperature of the switch 5 rises due to the heating from the LED lamp 3. When the temperature t of the switching device 5 (switching piece 53) becomes higher than the set temperature T, the bimetallic switching piece 53 moves away from the second output contact 52 and contacts the first output contact 51. Thereby, the input contact 50 and the 1st output contact 51 will be in a conduction state via the switching piece 53 (refer FIG. 3). As a result, the input current from the rectifier circuit 4 is supplied to the first circuit 1, and the supply current (constant current) converted (smoothed) into a constant current value by the first circuit 1 is converted into the LED lamp. 3 is supplied.

  Further, when the temperature of the lighting device A decreases and the temperature t of the switch 5 becomes equal to or lower than the set temperature T, the contact that contacts the switching piece 53 of the switch 5 is switched from the first output contact 51 to the second output contact 52 ( (See FIG. 3). As a result, the input current rectified by the rectifier circuit 4 is supplied to the LED lamp 3 via the second circuit 2.

  As shown in FIG. 3, when the switching piece 53 is in contact with the second output contact 52 in the switch 5, the input current from the rectifier circuit 4 flows to the second circuit 2. Since the resistor 21 is arranged in the second circuit 2 and the input current is pulsating (the current value fluctuates at a constant period), the resistor 21 is supplied to the LED lamp 3 via the second circuit 2. The supplied current is also pulsating (see FIG. 3). The brightness of the LED lamp 3 varies according to the pulsating current. In addition, since the frequency of this pulsating flow is high (for example, 120 Hz when 60 Hz alternating current is rectified), the human eye recognizes that the LED lamp 3 is lit with a constant luminance.

  Further, when the switching piece 53 is in contact with the first output contact 51, the input current from the rectifier circuit 4 flows to the first circuit 1. The first circuit 1 adjusts the voltage and outputs a supply current that is a direct current with a constant current value. The LED lamp 3 is lit with a constant luminance. In addition, the first circuit 1 can adjust the current value of the supply current by the switching operation of the switching element 11, and can also change the luminance of the LED lamp 3.

  That is, the lighting device A supplies an input current from the rectifier circuit 4 to the second circuit 2 and supplies a supply current from the second circuit 2 to the LED lamp 3 in an extremely low temperature environment where the stable operation of the first circuit 1 is difficult. Thus, the LED lamp 3 can be turned on immediately.

  In the second circuit 2, the input current from the rectifier circuit 4 is only stepped down by the resistor 21. Therefore, the supply current is a pulse wave and is easily affected by disturbances such as noise. On the other hand, the supply current output from the first circuit 1 is a smoothed direct current that is hardly affected by disturbances such as noise. As described above, the supply current from the second circuit 2 is supplied to the LED lamp 3 until the temperature of the first circuit 1 (element) reaches a temperature at which stable operation is possible. The LED lamp 3 is heated by the heat of lighting by the current supplied from the two circuits 2. Therefore, the period during which the supply current is supplied from the second circuit 2 to the LED lamp 3 is short, the time that is affected by disturbances such as noise can be shortened, and deterioration in the quality of the illumination light can be suppressed.

  From the above, the lighting device A according to the present invention can be turned on immediately even in a cryogenic state. And since the 1st circuit 1 is heated with the heat | fever by lighting of the LED lamp 3, the circuit which supplies a supply current can be switched from the 2nd circuit 2 to the 1st circuit 1 in a short period. For this reason, it is possible to shorten the period that is easily affected by disturbances such as noise, and it is possible to keep the quality of the illumination light high. Further, while the supply current is supplied through the first circuit 1, the luminance of the LED lamp 3 can be adjusted (dimmed), and the quality of the illumination light can be further improved.

  Note that the switch 5 is preferably disposed in the vicinity of an element (for example, the coil 12 and the smoothing capacitor 13) whose operation is difficult to stabilize in the low temperature environment of the first circuit 1. As a result, the set temperature T of the switch 5 can be determined at a temperature close to the temperature of the element that is difficult to operate in a low temperature environment. Thereby, it is possible to improve the switching accuracy of the switch 5.

  Further, the step-down DC / DC converter is exemplified as the first circuit 1, but the present invention is not limited to this, and a constant current can be supplied to the LED lamp 3, and further stable operation in a low temperature environment. Therefore, it is possible to widely adopt a circuit having a configuration having difficult elements. In addition, about the 1st circuit 1, it is set as the same DC / DC converter also in the following embodiment.

(Second Embodiment)
Another example of the lighting device according to the present invention will be described with reference to the drawings. FIG. 4 is a diagram showing the operation of another example of the illumination device according to the present invention. The lighting device of the present embodiment uses a switch using a switching piece 53 having a different property from that of the lighting device of the first embodiment. In addition, since the illuminating device of this embodiment and the illuminating device A of 1st Embodiment are the same as circuit diagram itself, the figure of FIG. 1 is substituted. The switch is also described with the same reference numerals.

  The switching piece 53 of the switching device used in the lighting device A has a bimetal configured to switch the contact point that the contact piece 53 contacts at one temperature (set temperature T). On the other hand, there is a configuration in which the switching piece 53 is configured to operate at two temperatures (a constant temperature range) by a combination of bimetallic plate materials (linear expansion coefficient) (for example, bimetal thermostud manufactured by Nippon Emerson Co., Ltd.). 10H11).

  As shown in FIG. 4, in the switch 5, when the temperature t rises, when the temperature t becomes higher than the first switching temperature T <b> 1, the contact that contacts the switching piece 53 is changed from the second output contact 52 to the first output contact 51. Switch to Further, when the temperature t decreases, the contact that contacts the switching piece 53 is switched from the first output contact 51 to the second output contact 52 when the temperature t becomes equal to or lower than the second switching temperature T2. The first switching temperature 1 is set higher than the temperature of the switch 5 at the lower limit of the temperature range in which the first circuit 1 (element) can operate stably. Further, the first switching temperature T1 is set higher than the second switching temperature T2.

  In this way, by setting the switching temperature of the switching device 5 when the temperature rises to a higher temperature, due to the temperature difference due to the location of the switching device 5 and the element of the first circuit 1 being separated, the device is It is possible to suppress switching to the first circuit 1 in a state where the heating is not sufficiently performed. Further, when the temperature decreases, the element itself generates heat, so that the element temperature is higher than the temperature t of the switch 5. Therefore, even if the switching is performed at the second switching temperature T2 that is lower than the first switching temperature T1 of the temperature t of the switching device 5, the temperature of the element is less likely to be lower than the operation lower limit temperature.

  Note that the second switching temperature T2 may be the same as the temperature of the switch 5 at the lower limit of the temperature range in which the first circuit 1 (element) can stably operate.

  Thus, when the temperature of the element (switch 5) rises, the first switching temperature higher than the temperature of the switch 5 at the lower limit of the temperature range in which the first circuit 1 (element) can stably operate. By switching the switching piece 53 to the first circuit 1 at T1, it is possible to suppress current from being supplied to the first circuit 1 when the temperature is lower than the temperature at which the element can stably operate. When the temperature decreases, the switching piece 53 is switched to the second circuit 2 at the second switching temperature T2, thereby extending the time during which the supply current is supplied from the first circuit 1 to the LED lamp 3. be able to. From the above, it is possible to reduce the time during which the supply current of the pulsating flow that is susceptible to disturbance such as noise is supplied to the LED lamp 3. Other features are the same as those in the first embodiment.

(Third embodiment)
Still another example of the illumination device according to the present invention will be described with reference to the drawings. FIG. 5 is a circuit diagram of still another example of the illumination device according to the present invention. As shown in FIG. 5, in the lighting device B, the first circuit 1 b includes a temperature sensor 16 (temperature measurement means) that measures the temperature of the coil 12, and includes a control unit 6 and a switch 7. It is the same as the illuminating device A shown in FIG. Accordingly, substantially the same parts as those of the illuminating apparatus A of the illuminating apparatus B are denoted by the same reference numerals, and detailed description of the same parts is omitted.

  The illumination device B includes a temperature sensor 16 that measures the temperature of the coil 12. The temperature sensor 16 may contact the coil 12 and measure the temperature of the coil 12, or may measure it in a non-contact manner. Then, the temperature of the coil 12 measured by the temperature sensor 16 is sent to the control unit 6 as temperature information. The control unit 6 is a processing circuit including an arithmetic circuit such as an MPU and a storage unit such as a memory. The control unit 6 is configured to operate the switch 5 based on temperature information from the temperature sensor 16. The switch 7 can flow the current from the rectifier circuit 4 to either the first circuit 1b or the second circuit 2 based on a control signal from the control unit 6 (for example, a switching element). , Relays, etc.).

  Further, the control unit 6 is configured to send a signal to the switching driver 15. For example, the control unit 6 is configured so that the switching driver 15 transmits the switching control signal to the switching element 11 only when the current from the rectifier circuit 4 is supplied to the first circuit 1b. 11 can be operated efficiently. In addition, since the temperature of the element (coil 12) is directly measured by the temperature sensor 16, it is possible to improve the control accuracy.

  The illuminating device B includes the temperature sensor 16 and the control unit 6, so that it is possible to cope with the case where the set temperature is one or two (or more). The operation of the lighting device B will be described with reference to the drawings. FIG. 6 is a flowchart showing the operation of the illumination device shown in FIG. Note that the flowchart shown in FIG. 6 shows the operation when there are two set temperatures (the same as in the second embodiment).

  First, the temperature τ of the coil 12 is measured by the temperature sensor 16 (step S11). The control unit 6 determines whether or not the temperature τ of the coil 12 is equal to or lower than the first switching temperature T1 (step S12). When the temperature τ of the coil 12 is equal to or lower than the first switching temperature T1 (Yes in step S12), the control unit 6 determines that it is preferable to supply current via the second circuit 2, and the input of the switch 7 The contact 70 and the second output contact 72 are connected (step S13), the process returns to step S11, and the temperature τ of the coil 12 is measured.

  When the temperature τ of the coil 12 is higher than the first switching temperature T1 (in the case of No in step S12), the control unit 6 determines that the first circuit 1 may be used, and the input contact 70 of the switch 7 The first output contact 71 is connected (step S14). Then, the temperature τ of the coil 12 is measured (step S15). At this time, since the temperature of the coil 12 is once higher than the first switching temperature T1, the next time the switch 7 is switched, the switching is performed at the second switching temperature T2. Therefore, the control unit 6 determines whether the temperature τ of the coil 12 is higher than the second switching temperature T2 (step S16).

  When the temperature τ of the coil 12 is higher than the second switching temperature T2 (Yes in step S16), the control unit 6 determines that the use of the first circuit 1b may be continued, returns to step S15, and returns to the coil 12 The temperature τ is measured. If the temperature τ of the coil 12 is equal to or lower than the second switching temperature T2 (No in step S16), the process returns to step S13, and the input contact 70 and the second output contact 72 of the switch 7 are connected.

  As described above, the control unit 6 measures the temperature τ of the coil 12 and accurately selects a circuit according to the operating state of the coil 12. Then, by changing the switching temperature between when the temperature τ of the coil 12 rises and when it falls, it is possible to suppress the instability of the operation due to the low temperature state of the coil 12 and to supply from the first circuit 1b. The time for supplying the current to the LED lamp 3 can be lengthened. Further, even when the coil 12 is changed to one having a different lower limit of the temperature at which stable operation is possible, it is only necessary to change the set temperature of the control unit 16 and the correspondence is simple. Other features are the same as those of the first and second embodiments.

  In this embodiment, the operation when there are two set temperatures (the same as in the second embodiment) is described as an example. However, the operation is not limited to this, and there is one set temperature (the first set temperature). As in the first embodiment). Alternatively, three or more set temperatures may be provided, and the operation may be performed so as to each have conditions for using the set temperatures. Moreover, although the coil 12 is mentioned as an element which becomes unstable in a cryogenic environment, it is not limited to this, The element which the control part 6 becomes unstable in cryogenic environments other than the coil 12 ( For example, the temperature of the smoothing capacitor 13) may be acquired, and the first circuit 1 or the second circuit 2 may be switched depending on the temperature. Further, the temperature information of two or more elements may be switched together (for example, when both elements satisfy a temperature condition that enables stable operation).

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this content. The embodiments of the present invention can be variously modified without departing from the spirit of the invention.

  A lighting device that lights a light source, a supply circuit 4 that supplies DC power, a first circuit 1 that converts power from the supply circuit 4 and supplies a constant current to the light source 3, and power from the supply circuit 4 Is provided with a second circuit that supplies the light source 3, a supply circuit 4, and a switch 5 that connects either the first circuit 1 (1 b) or the second circuit 2, and the switch 5 (7) The supply circuit 4 is connected to the second circuit 2 when the temperature of the element included in the first circuit 1 (1b) is lower than the set temperature.

  According to such an illumination device, while the operation of the elements (for example, the coil 12 and the smoothing capacitor 13) included in the first circuit 1 (1b) is unstable, the second circuit 2 is used to supply power to the light source. After being supplied and heated to such an extent that the element is stabilized, the first circuit 1 (1b) capable of supplying a constant current is used. Thereby, the instant lighting performance is ensured by using the second circuit 2 with respect to the conventional lighting device that does not supply power to the light source until the element operates stably. Further, after the element can be stably operated, the first circuit 1 (1b) that outputs a constant current is used, so that flickering of illumination light due to the influence of disturbance such as noise can be suppressed. Further, since the light source 3 and the first circuit 1 (1b) are close to each other, the elements of the first circuit 1 (1b) are easily heated by the heat of the light source 3.

  In the illumination device according to the present invention, the light source 3 may be disposed in proximity to the first circuit 1 (1b).

  According to such an illuminating device, it is possible to efficiently heat the elements included in the first circuit 1 (1b) with heat when the light source 3 is turned on. As a result, the elements included in the first circuit 1 (1b) can be quickly raised to a temperature at which stable operation is possible, and the supply current supplied to the light source 3 via the second circuit 2 (sensitive to disturbances such as noise). It is possible to shorten the time during which the pulse wave current is supplied. Thereby, it is possible to suppress the quality degradation of the illumination light of an illuminating device.

  In the lighting device according to the present invention, the set temperature includes a first switching temperature T1 and a second switching temperature T2 lower than the first switching temperature T2, and the switch 5 (7) includes the first circuit. When the temperature of the element 1 (1b) rises and becomes higher than the first switching temperature T1, the connection of the supply circuit 4 is switched to the first circuit 1 (1b), and the temperature of the element of the first circuit 1 (1b) falls. When the temperature is lower than the second switching temperature T2, the connection of the supply circuit 4 is switched to the second circuit 2.

  According to such a lighting device, the element 12 is not sufficiently heated by increasing the switching temperature of the switch 5 (7) when the temperature of the element 12 of the first circuit 1 (1b) rises. Therefore, it is possible to prevent the element 12 from being stably operated. Further, by lowering the switching temperature of the switching device 5 (7) when the temperature of the element 12 is lowered, the temperature at which the element 12 can operate sufficiently stably due to the temperature difference between the measured temperature and the element itself. Nevertheless, switching can be suppressed. Thereby, the time for supplying the constant current to the light source 3 can be lengthened, and flickering can be suppressed.

  In the lighting device according to the present invention, the switch 5 is a switch using a bimetal.

  According to such an illuminating device, it is possible to simplify the configuration and reduce the frequency of maintenance by using the bimetal for the switching device 5 (the switching piece 53).

  In the illuminating device according to the present invention, the temperature measuring unit 16 that measures the temperature of the element of the first circuit 1b, and the control that acquires the temperature measured by the temperature measuring unit 16 and controls the switch 7 based on the acquired temperature. Part 6.

  According to such an illuminating device, since the temperature measuring means 16 measures the temperature of the element 12 of the first circuit 1b, the accurate temperature of the element can be acquired. Then, based on the temperature, the control unit 6 determines whether or not the element can stably operate. Therefore, the switch 7 can be switched at a temperature close to the lower limit of the temperature at which the element can stably operate.

  In the lighting device according to the present invention, the supply circuit 4 includes a rectifier circuit that converts an AC voltage into a DC voltage.

  According to such an illuminating device, it is not necessary to prepare a direct-current power source in a place where alternating current is supplied, and versatility can be improved accordingly.

  In the illumination device according to the present invention, the first circuit 1 (1b) is a DC / DC converter.

  According to such an illuminating device, the current value (voltage value) of the supplied power can be appropriately adjusted according to the rated current (voltage) of the light source 3. Thereby, it is possible to suppress a problem that the light source 3 is damaged or the life thereof is shortened.

  The illumination device according to the present invention includes a heat transfer member Bd that is in contact with the element 12 and the light source 3 of the first circuit 1 (1b) and transfers heat of the light source to the element.

  According to such an illuminating device, the element 12 of the first circuit 1 (1b) can be efficiently heated by the heat generated when the light source 3 is lit by the supply current from the second circuit 2. Thereby, since a device such as a heater for heating the element 12 of the first circuit 1 (1b) is unnecessary, the lighting device can be simplified and the power consumption can be reduced.

  The present invention includes a light source that operates (lights) with a direct current, and is suitable as a lighting device that is driven in a low-temperature environment.

1 First Circuit 11 Switching Element 12 Coil 13 Capacitor (Smoothing Capacitor)
14 Diode 15 Switching driver 16 Temperature sensor (temperature detection means)
2 Second circuit 21 Resistor 3 LED lamp (light source)
4 rectifier circuit 5 switch 50 input contact 51 first output contact 52 second output contact

Claims (5)

A supply circuit for supplying DC power;
A first circuit for converting power from the supply circuit and supplying a constant current to the light source;
A second circuit for supplying power from the supply circuit to the light source;
A lighting device comprising: the supply circuit; and a switch that connects either the first circuit or the second circuit,
The switching device connects the supply circuit to the second circuit when the temperature of an element included in the first circuit is lower than a preset temperature.   The lighting device according to claim 1, wherein the light source is disposed in proximity to the first circuit. The set temperature includes a first switching temperature and a second switching temperature lower than the first switching temperature,
The switch switches the connection of the supply circuit from the second circuit to the first circuit when the temperature of the element of the first circuit rises and becomes higher than the first switching temperature, and the switch of the element of the first circuit The lighting device according to claim 1 or 2, wherein when the temperature falls and becomes lower than the second switching temperature, the connection of the supply circuit is switched from the first circuit to the second circuit. Temperature measuring means for measuring the temperature of the element of the first circuit;
The lighting device according to any one of claims 1 to 3, further comprising: a control unit that acquires a temperature measured by the temperature measuring unit and controls the switch based on the acquired temperature.   5. The lighting device according to claim 1, further comprising a heat transfer member that contacts the element of the first circuit and the light source and transfers heat of the light source to the element of the first circuit. 6.

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