Lighting fixture

Abstract

To solve the problem in which there is a lighting method in which even small brightness fluctuations caused by switching between two dimming modes of one for high current and the other for minute current become an issue in LED dimming control.SOLUTION: By including an LED drive circuit control IC that outputs LED drive signals in response to dimming input, an IC that reads the dimming input and the output of the LED drive circuit control IC and outputs correction signals accordingly, and an LED drive circuit, the fluctuations during mode switching is reduced.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a lighting device using LEDs.

Background Art

[0002] In recent years, lighting fixtures in many spaces have mainly become LED lighting, and not only is it simply a matter of replacing them with LED lighting, but there are also an increasing number of situations where the quality of light of LED lighting is being pursued. In particular, in situations where lighting fixtures are used as part of spatial staging, such as indirect lighting, since the quality of light is required in the first place, this is particularly prominent.

[0003] Furthermore, generalization has progressed, and there is a strong demand for LED lighting that can be used directly with commercial power supplies. Among the electronic components that drive LEDs, many products that assume the use of commercial power supplies have been put into practical use and sold.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] An object of the present invention is to provide an LED lighting device having a uniform dimming level in dimming. In particular, it relates to an LED lighting device in which a plurality of fixtures called linear types are continuously installed. Such a linear LED lighting device, in the case of handling a single unit like an LED bulb, even a subtle difference that is not noticeable will be easily noticed by humans when they are arranged side by side in a uniform manner at zero distance and adjacent to each other.

Means for Solving the Problems

[0006] In order to solve the above problems, a lighting device according to an aspect of the present invention includes an LED drive circuit control IC that switches between two or more drive methods according to a dimming input and outputs an LED drive output, an IC that reads the dimming input and the output of the LED drive circuit control IC and outputs a correction output according thereto, and an LED drive circuit.

Effect of the Invention

[0007] According to the present invention, it is possible to obtain a lighting device capable of performing uniform dimming in the entire dimming range, particularly in a lighting scene including a dimming operation in which the brightness is 5% or less.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiment for Carrying Out the Invention

[0009] First, the LED drive circuit control IC used in the aspect of the present invention will be described. In recent years, a constant current is often adopted as the LED drive method. This is because it is not affected by variations due to the forward voltage or changes during operation, and the LED can be lit at the target brightness by driving it with the set current.

[0010] As described above, due to the generalization of LEDs and the increasing demand for performance, in addition to driving with a commercial power supply, LED drive circuit control ICs corresponding to dimming are on the market. These LED drive circuit control ICs generally control an LED drive circuit that can output a switching current for driving an LED.

[0011] In the dimming operation of a lighting fixture, there may be a requirement for a very small output, such as 5% or less, and even 1% or less. Since the operating current values have a significant difference, it is difficult to uniformly control and handle using a simple circuit configuration with general elements. To address this, such control ICs for LED drive circuits generally have two current control modes, such as a current continuous mode control method that stably outputs at high output and a current discontinuous mode control method that stably outputs at low output.

[0012] Figure 2 is a diagram showing the variation in output current with respect to the dimming input of such a control IC for an LED drive circuit. 200, 210, and 220 respectively indicate the outputs at the maximum current, typical, and minimum current. Also, 201, 211, and 221 indicate the switching points of the two current control modes described above. Generally, since the output characteristics change when the control method switches, strict control of the switching point is required to make the characteristics completely homogeneous, but this is difficult.

[0013] Figure 2 is a conceptual diagram of the behavior of light when the entire inner surface is a diffusing surface. Among the light emitted from the LED, the light hitting the inner surface of the cylindrical body will all be diffused on the inner surface. As a result, the inside of the cylindrical body emits light evenly, and the inside of the cylindrical body is visually recognized as a large light-emitting surface.

[0014] Since the brightness of the LED is proportional to the current value, as shown in Figure 2, the variation in the switching point of the current control mode will directly lead to a difference in brightness due to a subtle difference in current values in the dimming state. When used singly, such as in an LED bulb, since the emissions are separated from each other, the human eye does not notice the fine difference in brightness and there is no problem. However, in the case of arranging multiple LED lighting fixtures continuously, such as when installing lighting fixtures in a line, the difference in brightness is only emphasized and felt as a problem when the emissions of multiple LED lighting fixtures are adjacent.

[0015] Figure 1 is a block diagram showing the basic configuration of the present invention. The control means 101 for the LED drive circuit is supplied with a dimming current from the dimming circuit 102 and controls the current flowing into the LED drive circuit 103. The correction means 104 detects the dimming current supplied to the control means 101 for the LED drive circuit and the current flowing through the LED drive circuit 103, and outputs a correction output according to the set value. Thereby, it is possible to suppress variations in the performance of the control means 101 for the LED drive circuit that occur during dimming.

[0016] Figure 3 is a circuit diagram showing one aspect of the present invention. Parts that do not contribute to the invention are omitted. This circuit is an LED lighting circuit that is dimmed by a current controlled by a phase control dimmer. 301 is a control IC for the LED drive circuit. 302 is a control IC for correction. 303 is a general full-wave rectifier filter circuit. 304 is an LED drive circuit using a general DCDC converter using a MOSFET.

[0017] The filter circuit 303 is a general full-wave rectifier filter circuit. The LED drive circuit 304 is a constant current drive circuit for LEDs using a general DCDC converter using a MOSFET. Regarding the detailed operation, since it is a general configuration and operation, it is omitted here, but the MOSFET is switched by the PWM signal of the control IC for the LED drive circuit to supply a lighting current according to the dimming state to the LEDs.

[0018] The phase control current is input to the control IC 301 for the LED drive circuit and the correction control IC 302 through the filter circuit 303. The control IC 301 for the LED drive circuit outputs a switching signal current to the LED drive circuit 304 according to the input.

[0019] The source terminal side of the MOSFET is connected to the current detection terminal 311 of the control IC 301 for the LED drive circuit via a current detection resistor, and is configured to monitor the current flowing through the MOSFET from such a voltage. Further, it is input to the correction control IC 302 via the operational amplifier 313.

[0020] The correction control IC 302 holds a reference value of the output value with respect to the phase control current input via the filter circuit 303, compares it with the current value detected and input from the source terminal side of the MOSFET, and further performs output control to the current detection terminal 311 so as to limit the output of the LED drive circuit 304 with respect to this.

[0021] FIG. 4 is a diagram showing the output current before and after variation correction by the circuit of one aspect of the present invention. The correction control IC 302 performs correction by limiting the switching output of the control IC for the LED drive circuit so that the variation in the current control mode switching timing becomes substantially uniform.

Industrial Applicability

[0022] In this way, with a simple configuration, it is possible to perform uniform dimming control output for a plurality of LED illuminations using a generally distributed control IC for an LED drive circuit. Note that any combination of the above-described components, and those configured by converting the expression of the present invention into an apparatus, method, system, etc. are also effective as aspects of the present invention.

Claims

1. A lighting fixture that receives a dimming current output from a dimmer and lights up at a dimming point, comprising switching control means having two or more dimming control modes for the dimming current, and lighting control means having means for correcting and controlling a switching output when the dimming current decreases to a reference value corresponding to the dimming current to the switching control means.

2. The lighting fixture according to claim 1, wherein the switching control means has at least two dimming modes: a continuous dimming mode and a discontinuous dimming mode.

3. The lighting fixture according to claim 1 or 2, wherein the means for correcting and controlling controls so as to reduce the output current of the switching output.

4. The lighting fixture according to claims 1 to 3, wherein the switching control means has a current detection terminal.

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