Lighting devices and emergency lighting fixtures

Abstract

To reduce an error of current flowing in a light source with respect to a target value.SOLUTION: A first end of a first resistor R1 is connected to a light source 2 and a second resistor R2 is connected between a second end of the first resistor R1 and a reference voltage GND. A first current detection unit 6 is inputted with a difference voltage ΔV1 between both ends of the first resistor R1, and outputs a first detection signal S1. A first control unit 8 performs constant current control on an output of a first lighting circuit 3 which lights a light source 2 with power supplied from a first power supply, based on the first detection signal S1. A second current detection unit 7 is inputted with a voltage V2 of a connection point PT1 between the first resistor R1 and a second resistor R2, and outputs a second detection signal S2. A second control unit 9 performs constant current control on the output of a second lighting circuit 4 which lights the light source 2 with power supplied from a second power supply, based on the second detection signal S2. One of the first power supply P1 and the second power supply P2 is a normal power supply and the other is an emergency power supply.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a lighting device and an emergency lighting fixture, and more particularly to a lighting device that is powered by a plurality of power sources to light a light source, and an emergency lighting fixture including the lighting device.

Background Art

[0002] As a conventional example, the light-emitting device described in Patent Document 1 is exemplified. The light-emitting device described in Patent Document 1 (hereinafter referred to as the conventional example) is used in an induction lamp device. The housing of the induction lamp device incorporates a lighting device. The lighting device includes a normal lighting circuit that receives power supply from an AC power source such as a commercial power source when the AC power source is energized and generates DC power to be supplied to a light source circuit. Further, the lighting device includes an emergency lighting circuit that receives power supply from a storage battery in an emergency such as a power failure and generates DC power to be supplied to the light source circuit. The normal lighting circuit and the emergency lighting circuit adjust the current value of the generated DC power based on a feedback signal from a current detection circuit that detects the current flowing through the light source.

[0003] The target current value of the current that the emergency lighting circuit passes through the light source is smaller than the target current value of the current that the normal lighting circuit passes through the light source. Therefore, the current detection circuit is configured such that the feedback signal output by the current detection circuit has approximately the same magnitude during emergency lighting when the emergency lighting circuit lights the light source and during normal lighting when the normal lighting circuit lights the light source. In the conventional example, the current detection circuit has two resistors connected in series with the light source and a switching element connected in parallel with one of the two resistors. The switching element is turned on during normal lighting and turned off during emergency lighting. By turning off the switching element during emergency lighting, the feedback signal is made to have approximately the same magnitude as during normal lighting.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

[0005] In the aforementioned lighting device, a switching element is provided to switch the feedback signal of the current detection circuit between normal lighting and emergency lighting. Therefore, a switching element and a control circuit for the switching element are required, resulting in a large circuit size. Furthermore, although the switching element is turned on during normal lighting, variations in the on-resistance of the switching element and temperature characteristics can cause large fluctuations in the feedback signal output by the current detection circuit, potentially increasing the error in the current flowing through the light source relative to the target current value.

[0006] The purpose of this disclosure is to provide a lighting device and an emergency lighting fixture that can reduce errors in the current flowing through the light source relative to a target value. [Means for solving the problem]

[0008] Book A lighting device according to one aspect of the disclosure comprises a first lighting circuit section, a second lighting circuit section, a first resistor, a second resistor, a first current detection section, a first control section, a second current detection section, and a second control section. The first resistor has its first end connected to the light source. The second resistor is connected between the second end of the first resistor and the reference potential. The first lighting circuit section is, The series circuit of the light source, the first resistor, and the second resistor is connected between the output terminals. Power supplied from the first power source Current is passed through the series circuit of the light source, the first resistor, and the second resistor. The light source is turned on. The second lighting circuit section is: The series circuit of the light source, the first resistor, and the second resistor is connected between the output terminals. Power supplied from the second power source By passing current through the series circuit of the light source, the first resistor, and the second resistor, Turn on the aforementioned light source. . beforeThe first current detection unit receives the differential voltage across the first resistor and outputs a first detection signal indicating the magnitude of the current flowing to the light source. Based on the first detection signal, the first control unit performs constant current control so that the current flowing from the first lighting circuit to the light source becomes a first target value. The second current detection unit receives the differential voltage across the second resistor and outputs a second detection signal indicating the magnitude of the current flowing to the light source. Based on the second detection signal, the second control unit performs constant current control so that the current flowing from the second lighting circuit to the light source becomes a second target value. The source is It is a regular power source. The aforementioned second power supply is This is an emergency power supply for providing power in the event of an emergency with the aforementioned regular power supply. The second target value is smaller than the first target value.

[0009] An emergency lighting fixture according to one aspect of the present disclosure comprises a lighting device, a light source, an emergency power supply, and a casing. The casing houses the lighting device, the light source, and the emergency power supply. [Effects of the Invention]

[0010] According to this disclosure, it is possible to reduce the error in the current flowing through the light source relative to the target value. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is an external perspective view of an emergency lighting fixture according to Embodiment 1 of this disclosure. [Figure 2] Figure 2 is an exploded perspective view of the same emergency lighting fixture. [Figure 3] Figure 3 is a circuit diagram of a lighting device according to Embodiment 1 of this disclosure. [Figure 4] Figure 4 is a circuit diagram of the lighting device according to the modified example 1 described above. [Figure 5] Figure 5 is a circuit diagram of the lighting device according to the modified example 2 described above. [Figure 6] Figure 6 is a circuit diagram of the lighting device according to the modified example 3 described above. [Figure 7] Figure 7 is a circuit diagram of a lighting device according to Embodiment 2 of this disclosure.

Embodiment for Carrying Out the Invention

[0012] The lighting device 1 and the emergency lighting fixture A1 according to the embodiments of the present disclosure will be described in detail with reference to the drawings. However, each of the figures described in the following embodiments is a schematic diagram, and the respective ratios of the sizes and thicknesses of the respective components do not necessarily reflect the actual dimensional ratios. Note that the configurations described in the following embodiments are merely examples of the present disclosure. The present disclosure is not limited to the following embodiments, and various modifications can be made according to the design and the like as long as the effects of the present disclosure can be achieved.

[0013] (Embodiment 1) (1) Overview FIG. 3 is a schematic circuit diagram of the lighting device 1 according to Embodiment 1.

[0014] The lighting device 1 according to the embodiment includes a first lighting circuit section 3, a second lighting circuit section 4, a first resistor R1, a second resistor R2, a first current detection section 6, a second current detection section 7, a first control section 8, and a second control section 9.

[0015] The first lighting circuit section 3 lights the light source 2 with the power supplied from the first power source P1.

[0016] The second lighting circuit section 4 lights the light source 2 with the power supplied from the second power source P2.

[0017] The first end of the first resistor R1 is connected to the light source 2. A second resistor R2 is connected between the second end of the first resistor R1 and the reference potential GND.

[0018] The first current detection section 6 receives the differential voltage ΔV1 between both ends of the first resistor R1 and outputs a first detection signal S1 indicating the magnitude of the current flowing through the light source 2.

[0019] <00​​

[0020] The second current detection unit 7 receives the voltage V2 at the connection point PT1 of the first resistor R1 and the second resistor R2 with respect to the reference potential GND, and outputs a second detection signal S2 that indicates the magnitude of the current flowing through the light source 2.

[0021] The second control unit 9 performs constant current control based on the second detection signal S2 so that the current I2 flowing from the second lighting circuit unit 4 to the light source 2 becomes the second target value.

[0022] One of the first power supply P1 and the second power supply P2 is the normal power supply, and the other of the first power supply P1 and the second power supply P2 is an emergency power supply to provide power in the event of an emergency with the normal power supply.

[0023] In the lighting device 1 of this embodiment, the first current detection unit 6 detects the differential voltage ΔV1 across the first resistor R1, and the second current detection unit 7 detects the voltage V2 at the connection point PT1 of the first resistor R1 and the second resistor R2. Therefore, by setting the resistance value of the first resistor R1 according to the target value (first target value) of the current I1 supplied to the light source 2 by the first lighting circuit unit 3, and setting the resistance value of the second resistor R2 according to the target value (second target value) of the current I2 supplied to the light source 2 by the second lighting circuit unit 4, a switching element for changing the resistance value of the detection resistor is not required, as in the conventional example. Furthermore, since the current flowing to the light source 2 flows through the series circuit of the first resistor R1 and the second resistor R2, the possibility of the current value fluctuating due to the on-resistance of the switching element, as in the conventional example, can be reduced, and there is an advantage in that the error in the target value (first target value and second target value) of the current flowing to the light source 2 can be reduced. Furthermore, since switching elements and their control circuits are not required compared to conventional examples, the circuit configuration of the lighting device 1 can be simplified, which has the advantage of allowing for miniaturization.

[0024] By the way, the lighting device 1 of Embodiment 1 is used in an emergency lighting fixture A1 (see Figures 1 and 2). In Embodiment 1, the first power supply P1 is a normal power supply such as a commercial AC power supply of AC100V / 200V, 50Hz / 60Hz. The second power supply P2 is an emergency power supply for supplying power to the light source 2 in emergencies such as a power outage of the first power supply P1, which is the normal power supply. The emergency power supply includes a power storage unit having, for example, one or more storage batteries.

[0025] When the normal power supply, which is the first power supply P1, is not experiencing a power outage, the first lighting circuit unit 3 lights the light source 2 with the power supplied from the first power supply P1. In other words, the first lighting circuit unit 3 is a normal lighting circuit that lights the light source 2 with the power supplied from the normal power supply.

[0026] When the primary power supply, the normal power supply, is out of service, the second lighting circuit unit 4 lights the light source 2 using power supplied from the emergency power supply, which is the second power supply P2. In other words, the second lighting circuit unit 4 is an emergency lighting circuit that lights the light source 2 using power supplied from the emergency power supply.

[0027] The emergency lighting fixture A1 according to Embodiment 1 comprises a lighting device 1 according to Embodiment 1, a light source 2, an emergency power supply (second power supply P2), and a body A10 (see Figures 1 and 2). The body A10 houses the lighting device 1, the light source 2, and the emergency power supply.

[0028] The emergency lighting fixture A1 according to Embodiment 1 has the advantage of reducing errors in the current flowing through the light source 2 relative to the target value, since it is equipped with the lighting device 1 according to Embodiment 1.

[0029] (2) Details of the emergency lighting fixture according to the embodiment The emergency lighting fixture A1 according to Embodiment 1 (hereinafter abbreviated as Emergency Lighting Fixture A1) will be described in detail with reference to the drawings. The emergency lighting fixture A1 described below is an emergency exit sign installed at an emergency exit or in a passageway to an emergency exit in a building such as an office or store. However, the emergency lighting fixture A1 according to this embodiment is not limited to an emergency exit sign, and may be, for example, a stairwell sign installed in a stairwell within a building, or an emergency light installed on the ceiling of a room. In the following description, unless otherwise specified, the up and down, front and back, and left and right directions indicated by arrows in Figure 1 are defined as the up and down, front and back, and left and right directions of the emergency lighting fixture A1.

[0030] The emergency lighting fixture A1 comprises a lighting device 1 (hereinafter abbreviated as lighting device 1) according to the embodiment, a main body A10, a light source unit A11, a display block A12, a battery unit BU1 which is a second power supply P2 (emergency power supply), and the like (see Figures 1 and 2).

[0031] The casing A10 is formed from a synthetic resin material into a rectangular box shape with an opening on the front (see Figure 2). The casing A10 houses the lighting device 1, battery unit BU1, terminal block 90, mounting plate 91, and the like.

[0032] The mounting plate 91 is formed in a plate shape from a metal material (see Figure 2). The mounting plate 91 is screwed to the inner bottom surface of the device body A10. The lighting device 1 and the terminal block 90 are screwed to the mounting plate 91 and housed inside the device body A10. The lighting device 1 and the terminal block 90 are electrically connected. The terminal block 90 is electrically connected to the power line that is drawn in from the power hole 96 (see Figure 2) provided on the bottom surface of the device body A10. In other words, the lighting device 1 is electrically connected to the first power supply P1, which is a normal power supply (e.g., commercial AC power), through the terminal block 90 and the power line.

[0033] The battery unit BU1 comprises a power storage section having one or more batteries and a case housing this power storage section. In this configuration, the battery unit BU1, equipped with the power storage section, provides a second power supply P2, which is an emergency power source. The battery unit BU1 is detachably mounted to the mounting plate 91. The battery unit BU1 is electrically connected to the lighting device 1 while mounted to the mounting plate 91.

[0034] Display block A12 includes a display panel 92, a light guide plate 93, and a holder 94 (see Figure 2).

[0035] The display panel 92 is formed in the shape of a rectangular flat plate from a translucent synthetic resin material such as acrylic resin or polycarbonate resin. However, the display panel 92 may be formed from a translucent material other than synthetic resin, such as quartz glass. A pictogram 921 for evacuation guidance is displayed on the front surface (display surface 920) of the display panel 92 (see Figure 1).

[0036] The light guide plate 93 is formed in the shape of a rectangular flat plate from a light-transmitting synthetic resin material such as acrylic resin or polycarbonate resin. The light guide plate 93 is positioned behind the display panel 92 so that its front surface faces the rear surface of the display panel 92 (see Figure 2). Light emitted from the light source unit A11 is incident on the upper surface (incident surface 930) of the light guide plate 93. The light incident on the incident surface 930 is guided through the light guide plate 93 and emitted from the front surface of the light guide plate 93. The display panel 92 is then illuminated by the light emitted from the emission surface of the light guide plate 93.

[0037] The holder 94 is formed from a non-transparent synthetic resin material in the shape of a rectangular box (frame) with an open front and top. The holder 94 holds the display panel 92 and the light guide plate 93, with the display panel 92 positioned in front of the light guide plate 93 (see Figure 2).

[0038] The display block A12 is attached to the body A10 so as to cover the remaining portion of the opening of the body A10, excluding the upper part where the light source unit A11 is attached (see Figure 1).

[0039] The light source unit A11 includes a light source 2 (see Figure 3), a light guide that guides the light emitted from the light source 2, and a housing 95 that houses the light source 2 and the light guide (see Figure 2).

[0040] The housing 95 is formed in the shape of a long box with its bottom and rear open. The light source 2, LED 21, is mounted on a substrate and housed in one end (right end) along the longitudinal direction of the housing 95. The light guide is formed in the shape of a long rectangular prism. The light guide is housed in the housing 95 with one end face (right end face) along the longitudinal direction facing the LED 21, and its side (bottom) along the longitudinal direction facing the opening in the bottom of the housing 95. A portion of the substrate on which the LED 21 is mounted (hereinafter referred to as the projection 97) protrudes from the rear surface of the housing 95 (see Figure 2).

[0041] The light source unit A11 is attached to the main body A10 by fitting it into the upper front of the main body A10. At this time, the projection 97 is inserted into the connector 98 located in the upper right corner of the main body A10, thereby electrically connecting the light source unit A11 (light source 2) and the lighting device 1 via the connector 98 and electric wires (not shown).

[0042] Furthermore, when the light source unit A11 is attached to the body A10, the incident surface 930 of the light guide plate 93 and the output port of the light source unit A11 face each other in the vertical direction. Therefore, almost all of the light emitted from the output port of the light source unit A11 enters the light guide plate 93 from its incident surface 930. The light that enters the light guide plate 93 travels through the light guide plate 93, undergoes total internal reflection at the rear surface of the holder 94, and is emitted forward from the output surface of the light guide plate 93 to illuminate the display panel 92.

[0043] (3) Details of the lighting device according to the embodiment Next, the lighting device 1 will be described in detail with reference to the circuit diagram in Figure 3.

[0044] As described above, the lighting device 1 comprises a first lighting circuit section 3, a second lighting circuit section 4, a first resistor R1, a second resistor R2, a first current detection section 6, a second current detection section 7, a first control section 8, and a second control section 9. The lighting device 1 also further comprises a power outage detection section 10.

[0045] Light source 2 comprises, for example, multiple LEDs connected in series. Note that light source 2 may have only one LED. Furthermore, light source 2 may be composed of an organic EL (electroluminescent) or the like.

[0046] The first power source P1 is a regular power source, such as a commercial AC power source.

[0047] The second power source P2 is a power source for supplying power in emergencies such as power outages of the first power source P1, and is realized, for example, by a power storage unit having one or more batteries. In the event of an emergency such as a power outage of the first power source P1, the second lighting circuit unit 4, the second current detection unit 7, and the second control unit 9 operate using power supplied from the second power source P2, which is the emergency power source. The lighting device 1 may further include a charging circuit that charges the second power source P2 with power supplied from the first power source P1, which is the normal power source.

[0048] The first lighting circuit 3 lights the light source 2 with power supplied from the first power supply P1. The first lighting circuit 3 includes a rectifier circuit that rectifies the AC voltage input from the first power supply P1, which is a commercial AC power supply, a smoothing circuit that smooths the output voltage of the rectifier circuit, a first voltage conversion circuit that converts the voltage value of the output voltage of the smoothing circuit, and so on. The first voltage conversion circuit is, for example, a flyback converter using a transformer and a switching element. Note that the first voltage conversion circuit is not limited to a flyback converter, and may be a forward converter or the like.

[0049] The second lighting circuit section 4 lights the light source 2 with power supplied from the second power supply P2. The second lighting circuit section 4 includes a second voltage conversion circuit, etc., which converts the voltage value of the DC voltage input from the second power supply P2. The second voltage conversion circuit is, for example, a flyback converter using a transformer and a switching element. Note that the second voltage conversion circuit is not limited to a flyback converter, and may be a forward converter, etc.

[0050] A series circuit consisting of a light source 2, a first resistor R1, and a second resistor R2 is connected between the output terminals of the first lighting circuit 3 and the output terminals of the second lighting circuit 4, respectively. The light source 2 has one or more LEDs 21. The high-potential output terminal of the first lighting circuit 3 is connected to the first terminal of the light source 2 via a diode. The high-potential output terminal of the second lighting circuit 4 is also connected to the first terminal of the light source 2. The first terminal of the first resistor R1 is connected to the second terminal of the light source 2. The second resistor R2 is connected between the second terminal of the first resistor R1 and the reference potential GND. In the following description, the series circuit of the first resistor R1 and the second resistor R2 connected in series with the light source 2 may also be referred to as the current detection resistor module 5. Note that the first resistor R1 is composed of one resistor, but the first resistor R1 may be composed of multiple resistors connected in series or parallel. Similarly, the second resistor R2 is composed of one resistor, but the second resistor R2 may be composed of multiple resistors connected in series or parallel.

[0051] The power outage detection unit 10 detects whether the first power supply P1 is experiencing a power outage by comparing the output voltage of the first lighting circuit unit 3 with a predetermined reference voltage, and outputs a power outage detection signal S3 indicating the presence or absence of a power outage to the first control unit 8 and the second control unit 9. The power outage detection unit 10 may also directly detect the presence or absence of voltage input from the first power supply P1, for example, by comparing the input voltage from the first power supply P1 with a reference voltage to detect whether the first power supply P1 is experiencing a power outage.

[0052] The first current detection unit 6 is a differential amplifier circuit configured using, for example, an operational amplifier. The differential voltage ΔV1 across the first resistor R1 is input to the first current detection unit 6. The first current detection unit 6 outputs a first detection signal S1, which is an amplified version of the differential voltage ΔV1, to the first control unit 8.

[0053] If the first power supply P1 is not experiencing a power outage, the first control unit 8 controls the switching operation of the switching elements in the first lighting circuit unit 3 based on the first detection signal S1 so that the current value of the current I1 flowing from the first lighting circuit unit 3 to the light source 2 matches the first target value.

[0054] The second current detection unit 7 includes, for example, an amplification circuit using an operational amplifier. The voltage V2 at the connection point PT1 of the first resistor R1 and the second resistor R2, that is, the voltage V2 at the connection point PT1 relative to the reference potential GND, is input to the second current detection unit 7. The second current detection unit 7 outputs a second detection signal S2, which is an amplified version of the voltage V2, to the second control unit 9.

[0055] When the first power supply P1 is in a state of power outage, the second control unit 9 controls the switching operation of the switching elements in the second lighting circuit unit 4 based on the second detection signal S2 so that the current value of the current I2 flowing from the second lighting circuit unit 4 to the light source 2 matches the second target value.

[0056] Here, the second target value for the current I2 that the second lighting circuit 4 supplies to the light source 2 when the first power supply P1 is down (emergency) is set to a smaller value than the first target value for the current I1 that the first lighting circuit 3 supplies to the light source 2 when the first power supply P1 is down (normal). This is because when the first power supply P1 is down, it is assumed that the surroundings are dark, and if the brightness of the light source 2 is set to the same brightness as under normal conditions, the light from the light source 2 will be too bright.

[0057] The first control unit 8, which controls the first lighting circuit unit 3 that lights up the light source 2 under normal conditions, controls the current flowing through the light source 2 based on the differential voltage ΔV1 across the first resistor R1. Therefore, the resistance value of the detection resistor that detects the current flowing through the light source 2 under normal conditions is the resistance value of the first resistor R1. Accordingly, the resistance value of the first resistor R1 should be set to a value corresponding to the first target value, which is the target value of the current that flows through the light source 2 under normal conditions.

[0058] On the other hand, the second control unit 9, which controls the second lighting circuit unit 4 that lights up the light source 2 in an emergency, controls the current flowing through the light source 2 based on the voltage V2 at the connection point PT1 of the first resistor R1 and the second resistor R2. Therefore, the resistance value of the detection resistor that detects the current flowing through the light source 2 in an emergency is the resistance value of the second resistor R2. Accordingly, the resistance value of the second resistor R2 should be set to a value corresponding to the second target value, which is the target value of the current to flow through the light source 2 in an emergency. Since the second target value is smaller than the first target value, the resistance value of the second resistor R2 is set to a larger value than that of the first resistor R1.

[0059] Thus, in this embodiment, the resistance values ​​of the first resistor R1 and the second resistor R2 can be set to values ​​corresponding to the first target value and the second target value, respectively, eliminating the need for a switching element to switch the resistance value of the detection resistor, as in the conventional example. In the conventional example, the resistance value of the detection resistor is switched by turning on or off a switching element connected in parallel with a part of the detection resistor. Therefore, when the switching element is on, the on-resistance of the switching element causes an error in the detection result of the current flowing through the light source 2, which may increase the error in the current flowing through the light source 2 relative to the target current. In the lighting device 1 of this embodiment, the switching element for switching the resistance value of the detection resistor can be eliminated compared to the conventional example, so the error between the current flowing through the light source 2 and the target current caused by the on-resistance of the switching element can be eliminated, and the error between the current flowing through the light source 2 and the target current (first target value and second target value) can be reduced. Furthermore, compared to the conventional example, since the switching element and its control circuit for switching the resistance value of the detection resistor are unnecessary, the circuit configuration of the lighting device 1 can be simplified, and the lighting device 1 can be made smaller.

[0060] (4) Variations The above embodiments are merely one of many embodiments of this disclosure. The above embodiments can be modified in various ways depending on the design, etc., as long as they achieve the objectives of this disclosure.

[0061] The following lists modifications of Embodiment 1 described above. The modifications described below can be combined and applied as appropriate.

[0062] (4-1) Experimental variation 1 Figure 4 shows the circuit diagram of the lighting device 1 of modified example 1.

[0063] The lighting device 1 of Modification 1 differs from the above embodiment in that it comprises a switch element SW1 connected in parallel with the first resistor R1 and a third control unit 11. Note that the configuration other than the switch element SW1 and the third control unit 11 is the same as that of the lighting device 1 in the above embodiment; therefore, the same reference numerals are used for common components, and their descriptions are omitted.

[0064] The switch element SW1 is, for example, an N-channel field-effect transistor. The switch element SW1 is off in the first state when the first lighting circuit 3 lights the light source 2, and on in the second state when the second lighting circuit 4 lights the light source 2. Specifically, the third control unit 11 controls the switch element SW1 to be on or off based on the power outage detection signal S3 from the power outage detection unit 10. The third control unit 11 controls the switch element SW1 to be off in the first state (normal operation) when the first lighting circuit 3 lights the light source 2, and controls the switch element SW1 to be on in the second state (emergency) when the second lighting circuit 4 lights the light source 2. The third control unit 11 operates on power supplied from the first power supply P1 or the second power supply P2.

[0065] If the power outage detection unit 10 does not detect a power outage of the first power supply P1, which is the normal power supply, the first lighting circuit unit 3 lights the light source 2 with power supplied from the first power supply P1, and the second lighting circuit unit 4 stops operating. More specifically, if the power outage detection unit 10 does not detect a power outage of the first power supply P1, the first control unit 8 operates the first lighting circuit unit 3 to light the light source 2, and the second control unit 9 stops the operation of the second lighting circuit unit 4. In addition, the third control unit 11 controls the switch element SW1 to turn off. When the switch element SW1 is turned off, the current flowing to the light source 2 flows through the first resistor R1 and the second resistor R2, and the differential voltage ΔV1 across the first resistor R1 is input to the first current detection unit 6. The first current detection unit 6 outputs a first detection signal S1 based on the differential voltage ΔV1 to the first control unit 8, and the first control unit 8 performs constant current control of the first lighting circuit unit 3 based on the first detection signal S1 so that the output current matches the first target value.

[0066] When the power outage detection unit 10 detects a power outage in the first power supply P1, which is the normal power supply, the first lighting circuit unit 3 stops operating due to the power outage in the first power supply P1, and the second lighting circuit unit 4 lights the light source 2 with power supplied from the second power supply P2. More specifically, when the power outage detection unit 10 detects a power outage in the first power supply P1, the second control unit 9 activates the second lighting circuit unit 4, and the second lighting circuit unit 4 lights the light source 2 with power supplied from the second power supply P2. In addition, the third control unit 11 controls the switch element SW1 to turn on. When the switch element SW1 is turned on, the current flowing to the light source 2 flows through the switch element SW1 and the second resistor R2, and the voltage V2 at the connection point between the first resistor R1 and the second resistor R2 is input to the second current detection unit 7. The second current detection unit 7 outputs a second detection signal S2 based on the voltage V2 to the second control unit 9, and the second control unit 9 performs constant current control of the second lighting circuit unit 4 based on the second detection signal S2 so that the output current matches the second target value. In this case, the current flowing to the light source 2 does not flow through the first resistor R1, but flows through the switch element SW1 which has a lower on-resistance than the first resistor R1. Therefore, power loss can be reduced compared to the case where current flows through both the first resistor R1 and the second resistor R2, and the consumption of the second power supply P2 can be suppressed.

[0067] (4-2) Modification 2 Figure 5 shows the circuit diagram of the lighting device 1 of modified example 2.

[0068] The lighting device 1 of the modified example 2 differs from the above embodiment in that it includes a switch element SW2 connected in parallel with the second resistor R2 and a third control unit 11. Note that the configuration other than the switch element SW2 and the third control unit 11 is the same as that of the lighting device 1 in the above embodiment; therefore, the same reference numerals are used for common components, and their descriptions are omitted.

[0069] The switch element SW2 is, for example, an N-channel field-effect transistor. The switch element SW2 is turned on in the first state when the first lighting circuit 3 lights the light source 2, and turned off in the second state when the second lighting circuit 4 lights the light source 2. Specifically, the third control unit 11 controls the switch element SW2 to turn on or off based on the power outage detection signal S3 from the power outage detection unit 10. The third control unit 11 controls the switch element SW2 to turn on in the first state (normal operation) when the first lighting circuit 3 lights the light source 2, and controls the switch element SW2 to turn off in the second state (emergency) when the second lighting circuit 4 lights the light source 2. The third control unit 11 operates on power supplied from the first power supply P1 or the second power supply P2.

[0070] If the power outage detection unit 10 does not detect a power outage of the first power supply P1, which is the normal power supply, the first lighting circuit unit 3 lights the light source 2 with power supplied from the first power supply P1, and the second lighting circuit unit 4 stops operating. More specifically, if the power outage detection unit 10 does not detect a power outage of the first power supply P1, the first control unit 8 operates the first lighting circuit unit 3 to light the light source 2, and the second control unit 9 stops the operation of the second lighting circuit unit 4. In addition, the third control unit 11 controls the switch element SW2 to turn on. When the switch element SW2 is turned on, the current flowing to the light source 2 flows through the first resistor R1 and the switch element SW2, and the differential voltage ΔV1 across the first resistor R1 is input to the first current detection unit 6. The first current detection unit 6 outputs a first detection signal S1 based on the differential voltage ΔV1 to the first control unit 8, and the first control unit 8 performs constant current control of the first lighting circuit unit 3 based on the first detection signal S1 so that the output current matches the first target value. In this case, the current flowing to the light source 2 does not flow through the second resistor R2, but flows through the switch element SW2 which has a lower on-resistance than the second resistor R2, thus reducing power loss compared to the case where current flows through both the first resistor R1 and the second resistor R2.

[0071] Furthermore, if the power outage detection unit 10 detects a power outage in the first power supply P1, which is the normal power supply, the first lighting circuit unit 3 stops operating due to the power outage in the first power supply P1, and the second lighting circuit unit 4 lights up the light source 2 with power supplied from the second power supply P2. Specifically, if the power outage detection unit 10 detects a power outage in the first power supply, the second control unit 9 operates the second lighting circuit unit 4, and the second lighting circuit unit 4 lights up the light source 2 with power supplied from the second power supply P2. In addition, the third control unit 11 controls the switch element SW2 to turn off. When the switch element SW2 is turned off, the current flowing to the light source 2 flows through the first resistor R1 and the second resistor R2, and the voltage V2 at the connection point PT1 between the first resistor R1 and the second resistor R2 is input to the second current detection unit 7. The second current detection unit 7 outputs a second detection signal S2 based on the voltage V2 to the second control unit 9, and the second control unit 9 performs constant current control of the second lighting circuit unit 4 based on the second detection signal S2 so that the output current matches the second target value.

[0072] (4-3) Modification 3 Figure 6 shows the circuit diagram of the lighting device 1 of modified example 3.

[0073] The lighting device 1 of Modification 3 differs from the above embodiment in that it comprises a first switch element SW1 connected in parallel with a first resistor R1, a second switch element SW2 connected in parallel with a second resistor R2, and a third control unit 11. Note that the components other than the first switch element SW1, the second switch element SW2, and the third control unit 11 are the same as those of the lighting device 1 of the above embodiment, so the same reference numerals are used for common components and their descriptions are omitted.

[0074] The first switch element SW1 and the second switch element SW2 are, for example, N-channel field-effect transistors. The first switch element SW1 and the second switch element SW2 are controlled to be on or off by the third control unit 11. Specifically, the third control unit 11 controls the first switch element SW1 and the second switch element SW2 to be on or off based on the power outage detection signal S3 from the power outage detection unit 10. In the first state (normal operation) when the first lighting circuit unit 3 lights up the light source 2, the third control unit 11 controls the first switch element SW1 to be off and the second switch element SW2 to be on. In the second state (emergency operation) when the second lighting circuit unit 4 lights up the light source 2, the third control unit 11 controls the first switch element SW1 to be on and the second switch element SW2 to be off. The third control unit 11 operates on power supplied from the first power supply P1 or the second power supply P2.

[0075] If the power outage detection unit 10 does not detect a power outage of the first power supply P1, which is the normal power supply, the first lighting circuit unit 3 lights up the light source 2 with power supplied from the first power supply P1, and the second lighting circuit unit 4 stops operating. More specifically, if the power outage detection unit 10 does not detect a power outage of the first power supply P1, the first control unit 8 operates the first lighting circuit unit 3 to light up the light source 2, and the second control unit 9 stops the operation of the second lighting circuit unit 4. In addition, the third control unit 11 controls the first switch element SW1 to turn off and the second switch element SW2 to turn on. When the first switch element SW1 is off and the second switch element SW2 is on, the current flowing to the light source 2 flows through the first resistor R1 and the second switch element SW2, and the differential voltage ΔV1 across the first resistor R1 is input to the first current detection unit 6. The first current detection unit 6 outputs a first detection signal S1 based on the differential voltage ΔV1 to the first control unit 8, and the first control unit 8 performs constant current control of the first lighting circuit unit 3 based on the first detection signal S1 so that the output current matches the first target value. In this case, current flows through the second switch element SW2, which has a lower on-resistance than the second resistor R2, and does not flow through the second resistor R2, which has a higher resistance than the first resistor R1. Therefore, power loss can be reduced compared to the case where current flows through both the first resistor R1 and the second resistor R2.

[0076] When the power outage detection unit 10 detects a power outage in the first power supply P1, which is the normal power supply, the first lighting circuit unit 3 stops operating due to the power outage in the first power supply P1, and the second lighting circuit unit 4 lights up the light source 2 with power supplied from the second power supply P2. More specifically, when the power outage detection unit 10 detects a power outage in the first power supply P1, the second control unit 9 operates the second lighting circuit unit 4, and the second lighting circuit unit 4 lights up the light source 2 with power supplied from the second power supply P2. In addition, the third control unit 11 controls the first switch element SW1 to be turned on and the second switch element SW2 to be turned off. When the first switch element SW1 is turned on and the second switch element SW2 is turned off, the current flowing to the light source 2 flows through the first switch element SW1 and the second resistor R2, and the voltage V2 at the connection point PT1 between the first resistor R1 and the second resistor R2 is input to the second current detection unit 7. The second current detection unit 7 outputs a second detection signal S2 based on the voltage V2 to the second control unit 9, and the second control unit 9 performs constant current control of the second lighting circuit unit 4 based on the second detection signal S2 so that the output current matches the second target value. In this case, the current flowing to the light source 2 does not flow through the first resistor R1, but flows through the first switch element SW1, which has a lower on-resistance than the first resistor R1. Therefore, power loss can be reduced compared to the case where current flows through both the first resistor R1 and the second resistor R2, and the consumption of the second power supply P2 can be suppressed.

[0077] (4-4) Modification 4 In the above embodiment, the first power supply P1 was the normal power supply and the second power supply P2 was the emergency power supply. However, in the lighting device 1 of the modified example 4, the second power supply P2 is the normal power supply and the first power supply P1 is the emergency power supply.

[0078] If the second power supply P2, which is the normal power supply, is not experiencing a power outage, the second lighting circuit unit 4 lights the light source 2 using the power supplied from the second power supply P2, which is the normal power supply. At this time, the voltage V2 of the low-side second resistor R2 is input to the second current detection unit 7, and a second detection signal S2 based on the voltage V2 is output to the second control unit 9, and the second control unit 9 performs constant current control of the second lighting circuit unit 4 based on the second detection signal S2.

[0079] If the second power supply P2, which is the normal power supply, experiences a power outage, the first lighting circuit unit 3 lights the light source 2 using power supplied from the first power supply P1, which is the emergency power supply. At this time, the differential voltage ΔV1 across the first resistor R1 is input to the first current detection unit 6, and a first detection signal S1 based on the differential voltage ΔV1 is output to the first control unit 8. The first control unit 8 then performs constant current control of the first lighting circuit unit 3 based on the first detection signal S1.

[0080] In the event of an emergency such as a power outage of the second power supply P2, which is the normal power supply, the first lighting circuit unit 3, the first current detection unit 6, and the first control unit 8 will operate using power supplied from the first power supply P1, which is the emergency power supply.

[0081] (4-5) Other variations In the above embodiment, the light source 2 is, for example, an LED 21, but it may also be an organic EL or the like.

[0082] In the above embodiment, the emergency lighting fixture A1 is an exit sign, but it may also be an emergency light. In the above embodiment, the first lighting circuit 3 and the second lighting circuit 4 light up the same light source 2, but the light source lit by the first lighting circuit 3 and the light source lit by the second lighting circuit 4 may be different light sources.

[0083] (Embodiment 2) Figure 7 shows a circuit diagram of the lighting device 1 according to Embodiment 2.

[0084] The lighting device 1 of Embodiment 2 differs from Embodiment 1 in that the differential voltage ΔV2 across the second resistor R2 is input to the second current detection unit 7, and the second current detection unit 7 outputs a second detection signal S2 indicating the magnitude of the current flowing through the light source 2. Note that the configuration other than the second current detection unit 7 is the same as that of the lighting device 1 of Embodiment 1, so the same reference numerals are used for common components and their descriptions are omitted.

[0085] The second current detection unit 7 is a differential amplifier circuit, for example, using an operational amplifier. The differential voltage ΔV2 across the second resistor R2 is input to the second current detection unit 7. The second current detection unit 7 outputs a second detection signal S2, which is an amplified version of the differential voltage ΔV2, to the second control unit 9.

[0086] Since the second current detection unit 7 detects the differential voltage ΔV2 across the second resistor R2, it can detect the current flowing through the light source 2 with greater accuracy compared to detecting the voltage V2 at the connection point PT1 between the first resistor R1 and the second resistor R2. The second control unit 9 performs constant current control of the current flowing from the second lighting circuit unit 4 to the light source 2 based on the second detection signal S2 from the second current detection unit 7, thus enabling more precise control of the current flowing through the light source 2.

[0087] The configuration described in Embodiment 2 can be applied in appropriate combination with the configuration described in Embodiment 1 (including modified versions). In other words, even in modified versions 1 to 4 of Embodiment 1, the second current detection unit 7 may be configured to detect the differential voltage ΔV2 across the second resistor R2, and the current flowing through the light source 2 can be detected with high accuracy.

[0088] (summary) As described above, the lighting device (1) of the first embodiment comprises a first lighting circuit section (3), a second lighting circuit section (4), a first resistor (R1), a second resistor (R2), a first current detection section (6), a first control section (8), a second current detection section (7), and a second control section (9). The first lighting circuit section (3) lights up the light source (2) with power supplied from a first power supply (P1). The second lighting circuit section (4) lights up the light source (2) with power supplied from a second power supply (P2). The first end of the first resistor (R1) is connected to the light source (2). The second resistor (R2) is connected between the second end of the first resistor (R1) and the reference potential (GND). The first current detection unit (6) receives the differential voltage (ΔV1) across the first resistor (R1) and outputs a first detection signal (S1) indicating the magnitude of the current flowing through the light source (2). Based on the first detection signal (S1), the first control unit (8) performs constant current control so that the current flowing from the first lighting circuit unit (3) to the light source (2) becomes a first target value. The second current detection unit (7) receives the voltage (V2) at the connection point (PT1) of the first resistor (R1) and the second resistor (R2) relative to a reference potential (GND) and outputs a second detection signal (S2) indicating the magnitude of the current flowing through the light source (2). Based on the second detection signal (S2), the second control unit (9) performs constant current control so that the current flowing from the second lighting circuit unit (4) to the light source (2) becomes a second target value. One of the first power supply (P1) and the second power supply (P2) is the normal power supply. The other of the first power source (P1) and the second power source (P2) is an emergency power source for supplying power in the event of an emergency with the normal power supply.

[0089] According to this embodiment, the error in the current flowing through the light source (2) relative to the target value can be reduced.

[0090] The lighting device (1) of the second embodiment includes a first lighting circuit (3), a second lighting circuit (4), a first resistor (R1), a second resistor (R2), a first current detection unit (6), a first control unit (8), a second current detection unit (7), and a second control unit (9). The first lighting circuit (3) lights up the light source (2) with power supplied from a first power supply (P1). The second lighting circuit (4) lights up the light source (2) with power supplied from a second power supply (P2). The first resistor (R1) has its first end connected to the light source (2). The second resistor (R2) is connected between the second end of the first resistor (R1) and a reference potential (GND). The first current detection unit (6) receives the differential voltage (ΔV1) across the first resistor (R1) and outputs a first detection signal (S1) indicating the magnitude of the current flowing through the light source (2). The first control unit (8) performs constant current control based on the first detection signal (S1) so that the current flowing from the first lighting circuit (3) to the light source (2) becomes a first target value. The second current detection unit (7) receives the differential voltage (ΔV2) across the second resistor (R2) as input and outputs a second detection signal (S2) indicating the magnitude of the current flowing to the light source (2). The second control unit (9) performs constant current control based on the second detection signal (S2) so that the current flowing from the second lighting circuit (4) to the light source (2) becomes a second target value. One of the first power supply (P1) and the second power supply (P2) is the normal power supply. The other of the first power supply (P1) and the second power supply (P2) is an emergency power supply for supplying power in the event of an emergency with the normal power supply.

[0091] According to this embodiment, the error in the current flowing through the light source (2) relative to the target value can be reduced.

[0092] The lighting device (1) of the third embodiment further comprises a switch element (SW1) connected in parallel with the first resistor (R1) in the first or second embodiment. The switch element (SW1) is off in the first state in which the first lighting circuit (3) lights the light source (2), and is on in the second state in which the second lighting circuit (4) lights the light source (2).

[0093] According to this embodiment, in the second state, current flows through the switch element (SW1) and the second resistor (R2), so power loss can be reduced compared to the case where current flows through the first resistor (R1) and the second resistor (R2).

[0094] The lighting device (1) of the fourth embodiment further comprises a switch element (SW2) connected in parallel with the second resistor (R2) in the first or second embodiment. The switch element (SW2) is turned on in the first state in which the first lighting circuit (3) lights the light source (2), and is turned off in the second state in which the second lighting circuit (4) lights the light source (2).

[0095] According to this embodiment, in the first state, current flows through the first resistor (R1) and the switching element (SW2), so power loss can be reduced compared to the case where current flows through the first resistor (R1) and the second resistor (R2).

[0096] The lighting device (1) of the fifth embodiment further comprises, in the first or second embodiment, a first switch element (SW1) connected in parallel with a first resistor (R1) and a second switch element (SW2) connected in parallel with a second resistor (R2). The first switch element (SW1) is off in the first state when the first lighting circuit (3) lights the light source (2), and is on in the second state when the second lighting circuit (4) lights the light source (2). The second switch element (SW2) is on in the first state and off in the second state.

[0097] According to this embodiment, in the first state, current flows through the first resistor (R1) and the switching element (SW2), so power loss can be reduced compared to the case where current flows through the first resistor (R1) and the second resistor (R2). Also, in the second state, current flows through the switching element (SW1) and the second resistor (R2), so power loss can be reduced compared to the case where current flows through the first resistor (R1) and the second resistor (R2).

[0098] The emergency lighting fixture (A1) of the sixth embodiment comprises a lighting device (1) of any of the first to fifth embodiments, a light source (2), an emergency power supply, and a body (A10). The body (A10) houses the lighting device (1), the light source (2), and the emergency power supply.

[0099] According to this embodiment, by providing a lighting device (1) that can be miniaturized, the emergency lighting fixture (A1) can be made smaller.

[0100] The configurations relating to the third to fifth aspects are not essential to the lighting device (1) relating to the first or second aspect, and can be omitted as appropriate. [Explanation of Symbols]

[0101] 1. Lighting device 2 light source 3 1st lighting circuit section 4 Second lighting circuit section 6. First current detection unit 7. Second current detection unit 8. First Control Unit 9. Second Control Unit A1 Emergency lighting fixtures A10 body GND reference potential P1 1st power supply P2 2nd power supply PT1 connection point R1 is the first resistor. R2 2nd resistor S1 First detection signal S2 Second detection signal SW1 Switch element (first switch element) SW2 Switch element (second switch element) V2 Voltage ΔV1 Differential voltage across the first resistor ΔV2 Differential voltage across the second resistor

Claims

1. A first resistor having its first end connected to a light source, A second resistor connected between the second terminal of the first resistor and the reference potential, A series circuit of the light source, the first resistor, and the second resistor is connected between the output terminals, and a first lighting circuit unit is provided that uses power supplied from the first power supply to flow current through the series circuit of the light source, the first resistor, and the second resistor to light up the light source. A series circuit of the light source, the first resistor, and the second resistor is connected between the output terminals, and a second lighting circuit unit is provided that uses power supplied from the second power supply to flow current through the series circuit of the light source, the first resistor, and the second resistor to light up the light source. A first current detection unit receives the differential voltage across the first resistor and outputs a first detection signal indicating the magnitude of the current flowing through the light source, A first control unit performs constant current control based on the first detection signal so that the current flowing from the first lighting circuit to the light source becomes a first target value, A second current detection unit receives the differential voltage across the second resistor and outputs a second detection signal indicating the magnitude of the current flowing through the light source, The system includes a second control unit that performs constant current control based on the second detection signal so that the current flowing from the second lighting circuit to the light source becomes a second target value, The first power supply is a normal power supply, The second power supply is an emergency power supply for supplying power in the event of an emergency with the normal power supply. The second target value is smaller than the first target value. Lighting device.

2. The lighting device according to Claim 1, The aforementioned light source, The aforementioned emergency power supply, A casing housing the aforementioned lighting device, the aforementioned light source, and the aforementioned emergency power supply, Equipped with, Emergency lighting equipment.

Images