JP5409316B2 - Surge suppression circuit and lighting device - Google Patents

Description

  The present invention relates to a surge suppression circuit and a lighting device that suppress external surges, for example.

  When external energy such as an external surge (for example, lightning) is applied to the lighting device regardless of the circuit operation, discharge occurs between any lands on the circuit board or between the element and the case. May occur. If there is an element with a low withstand voltage in the vicinity of the discharge location, this element may be damaged.

  Here, in order to prevent the occurrence of this problem, for example, as in Patent Document 1, a land is provided in a pattern in which one pole of a power source is connected and a pattern in which the case and the circuit board are connected at the same potential. There is a structure that discharges external surges between lands.

Japanese Utility Model Publication No. 6-52182

When a land is simply provided on one pole side of the power source and the side where the case and the circuit board are connected at the same potential as in Patent Document 1, an external surge is generated between the other pole of the power source and the ground. If it occurs, the energy cannot be sufficiently suppressed and the circuit element fails.
In addition, if the lands cannot be arranged at appropriate intervals due to conditions such as case dimensions, circuit board pattern, and resist, even if the voltage between the lands reaches the voltage that you want to discharge, there is no discharge between the lands. The device fails.

  An object of the present invention is to prevent a circuit element from failing even if an external surge occurs on either pole side of a power supply when, for example, a discharge land cannot be disposed at an appropriate position on both pole sides of the power supply. To do.

  A surge suppression circuit according to the present invention is a surge suppression circuit mounted on a circuit board having wiring, and is connected to a first pole of an AC power source to flow a current from the AC power source and a second diode of the AC power source. A rectifier circuit having a second diode connected to two poles and flowing a current from the AC power source, a capacitor connected in parallel to the first diode, a second pole of the AC power source and the second diode A second pole-side land provided in the wiring to be connected and a ground-side land provided in the wiring to be connected to the ground.

  According to the present invention, for example, when a discharge land cannot be disposed at an appropriate position on both pole sides of a power supply, it is possible to prevent a circuit element from malfunctioning even if an external surge occurs on either pole side of the power supply.

FIG. 3 is a circuit configuration diagram of lighting device 100 according to the first embodiment. FIG. 3 is an external view showing a circuit board 190 housed in a case 200 in the first embodiment. FIG. 3 shows a pattern of a circuit board 190 in the first embodiment. FIG. 3 is a diagram illustrating a surge current flow when an external surge is applied to the H side of the commercial power supply 101 in the first embodiment. FIG. 3 is a diagram illustrating a surge current flow when an external surge is applied to the N side of the commercial power supply 101 in the first embodiment. 4 is another example of a circuit configuration diagram of lighting device 100 according to Embodiment 1. FIG. FIG. 5 is a circuit configuration diagram of lighting device 100 according to Embodiment 2. The figure which shows the flow of a surge current when the external surge is applied to the H side of the commercial power source 101 in the second embodiment. The figure which shows the flow of a surge electric current when an external surge is applied to the N side of the commercial power supply 101 in Embodiment 2. FIG. 10 is another example of a circuit configuration diagram of the lighting device 100 according to Embodiment 2. FIG.

Embodiment 1 FIG.
Discharge lands are provided at appropriate intervals in the pattern connected to one pole of the power supply and the pattern connected to the case, and in parallel with the diode that conducts current from the other pole of the power supply among the diodes constituting the rectifier circuit. An external surge suppression circuit provided with a capacitor for suppressing external surge will be described.
An external surge is an overvoltage generated in an electric circuit by a large external energy such as a terminal.

FIG. 1 is a circuit configuration diagram of a lighting device 100 according to the first embodiment.
The configuration of the external surge suppression circuit in the first embodiment will be described below with reference to FIG.

  The lighting device 100 is an example of an electric appliance that uses an external surge suppression circuit. You may use the external surge suppression circuit demonstrated below for electric appliances other than the lighting device 100. FIG.

The lighting device 100 includes a power rectifier circuit 110, a light source lighting circuit 120, and a light source unit 130.
The power supply rectifier circuit 110 is a diode bridge that converts the alternating current into a direct current (pulsating current) by full-wave rectifying the alternating current supplied from the commercial power supply 101. However, the power supply rectifier circuit 110 may not be a diode bridge but may be another rectifier circuit using a diode (for example, a two-phase full-wave rectifier circuit).
The light source lighting circuit 120 is a circuit that controls the direct current obtained by the power supply rectifier circuit 110 and supplies the direct current obtained by the control to the light source unit 130 to light the light source. For example, the light source lighting circuit 120 includes a chopper circuit, and controls a direct current by the chopper circuit to obtain a voltage suitable for the light source.
The light source unit 130 includes a connection terminal to which a light source (for example, an LED lamp) is connected.

Hereinafter, one pole (line) side of the commercial power source 101 is referred to as “H (hot) side”, and the other pole side of the commercial power source 101 is referred to as “N (neutral) side”.
A terminal connected to the H side of the commercial power supply 101 and a terminal connected to the N side of the commercial power supply 101 are illustrated by double circles.

Among the four diodes constituting the power supply rectifier circuit 110, the diode 111 is connected between the H side of the commercial power supply 101 and the light source lighting circuit 120 and allows the current from the H side of the commercial power supply 101 to flow to the light source lighting circuit 120. Connect an external surge suppression capacitor in parallel.
Hereinafter, the capacitor for suppressing external surge is referred to as “external surge suppressing capacitor 191”.

In addition, a discharge land is provided in each of the wiring connected to the N side of the commercial power supply 101 and the wiring connected to the electrical connection portion of the case (hereinafter referred to as “case connection portion 192”).
Hereinafter, the land provided on the wiring connected to the N side of the commercial power supply 101 is referred to as “power supply N-side discharge land 194”, and the land provided on the wiring connected to the case connection portion 192 is referred to as “case connection portion discharge land 193”.

The wiring corresponds to a copper foil (conductor) that forms a pattern in a circuit board (also referred to as a printed board) described later.
The pattern is obtained by covering the wiring of the circuit board with a resist (protective film).
The land is a portion where the resist is not applied and the wiring is exposed.

  The external surge suppression circuit of the lighting device 100 is mounted on a circuit board, and the circuit board is housed in a case.

FIG. 2 is an external view showing circuit board 190 housed in case 200 in the first embodiment.
The circuit board 190 accommodated in the case 200 will be described below with reference to FIG.
FIG. 2A is a plan view showing an end portion of the circuit board 190 accommodated in the case 200, and FIG. 2B is a side view showing the circuit board 190 accommodated in the case 200. FIG.

  The case 200 includes a case bottom 210 to which a circuit board 190 on which an external surge suppression circuit is mounted is fixed, and a case top 220 that covers the circuit board 190.

A metal piece is provided on the circuit board 190 as the case connecting portion 192.
The case connecting portion 192 provided on the circuit board 190 and the screw connecting portion 230 provided on the case bottom 210 are fixed with the screws 231 to make the circuit board 190 and the case bottom 210 conductive.
The case bottom 210 is connected to the ground, and the case connecting portion 192 of the circuit board 190 has the same potential as the ground.

FIG. 3 is a diagram showing a pattern of the circuit board 190 in the first embodiment.
The positional relationship between the case connection portion discharge land 193 and the power supply N side discharge land 194 will be described below with reference to FIG.
In FIG. 3, the pattern portion of the circuit board 190 is represented by hatching.

The case connection portion discharge land 193 is provided on the pattern Pc to which the case connection portion 192 is connected, and the power supply N side discharge land 194 is provided on the pattern Pn to which the N side pole of the commercial power supply 101 is connected.
As a position where the case connection portion discharge land 193 and the power supply N side discharge land 194 are provided, the interval (insulation distance) between the case connection portion discharge land 193 and the power supply N side discharge land 194 is 2.5 mm or more and 3.0 mm or less. Select a position.

Further, the insulation distance between the different polarities (where a potential difference occurs) other than between the case connection portion discharge land 193 and the power supply N side discharge land 194 is determined by the interval between the case connection portion discharge land 193 and the power supply N side discharge land 194. Enlarge. For example, 6.0 mm or more is preferable.
The difference between the poles other than between the case connection portion discharge land 193 and the power supply N side discharge land 194 is, for example, an electronic component, a lead wire, or a land (case connection portion discharge land 193, power source N on the circuit board 190). The side discharge land 194 is excluded). Hereinafter, electronic components, lead wires, and lands (excluding the case connection portion discharge land 193 and the power supply N side discharge land 194) are referred to as “charging portions”.
Further, for example, between the different poles other than between the case connection portion discharge land 193 and the power supply N side discharge land 194 is one pole side (point A in FIG. 1) and the other pole side of the rectifier circuit (FIG. 1). Between the charging part connected to point C) and between the one pole side of the rectifier circuit and the other pole side of the rectifier circuit.

FIG. 4 is a diagram showing a surge current flow when an external surge is applied to the H side of the commercial power supply 101 in the first embodiment.
FIG. 5 is a diagram showing the flow of surge current when an external surge is applied to the N side of the commercial power supply 101 in the first embodiment.
The flow of surge current when an external surge occurs will be described below based on FIG. 4 and FIG.

As shown in FIG. 4, when an external surge is applied between the H side of the commercial power supply 101 and the external surge suppression capacitor 191 (earth), the surge current flows as shown by arrows (1) and (2). .
First, most of the surge current instantaneously flows to the external surge suppression capacitor 191 (arrow (1)). For this reason, a large current does not flow through the power rectifier circuit 110, and the power rectifier circuit 110 does not fail due to the surge current.
Further, the surge current is suppressed (attenuated) by the case connection portion 192, and the current suppressed by the external surge suppression capacitor 191 flows through the light source lighting circuit 120 located behind (after rectification, downstream) of the power supply rectifier circuit 110 ( Arrow (1)). For this reason, the light source lighting circuit 120 does not fail due to the surge current.
Then, the surge current reaches the power supply N side discharge land 194 via the light source lighting circuit 120 and is discharged to the case connection portion discharge land 193 (arrow (2)). That is, the surge current does not flow in the circuit of the lighting device 100. Thereby, failure of the circuit element which comprises the lighting device 100 can be prevented.

In the absence of the external surge suppression capacitor 191, the surge current flows through the diode 111 of the power supply rectifier circuit 110, causing the power supply rectifier circuit 110 (111) to fail.
Further, the surge current is not suppressed and flows through the light source lighting circuit 120, causing the circuit elements of the light source lighting circuit 120 to fail.

As shown in FIG. 5, when an external surge is applied between the N side of the commercial power supply 101 and the case connection portion 192, the surge current is discharged between the power supply N side discharge land 194 and the case connection portion discharge land 193. (Arrow (1)).
That is, surge current does not flow in the circuit. Thereby, failure of the circuit element which comprises the lighting device 100 can be prevented.

  Next, the insulation distance between the discharge lands (193, 194) will be described.

The maximum voltage of a commercial power supply (power supplied from an electric power company) is generally 254 V (volt). When the commercial power supply voltage is 254 V, a maximum of 360 V (peak voltage) is between the commercial power supply and the ground. Applied.
In a state where this peak voltage (360 V) is applied, the minimum value of the insulation distance at which no discharge occurs between the discharge lands is “2.5 mm”.
In other words, if the insulation distance between the discharge lands is 2.5 mm or more, it is possible to prevent discharge between the discharge lands when no external surge is generated.

On the other hand, when an external surge exceeding 6 kV (kilovolt) occurs, if no discharge occurs between the discharge lands, many electronic components will fail. In a typical failure, the diode bridge constituting the rectifier circuit is short-circuit broken, and the fuse of the lighting device is disconnected. Although it is possible to increase the durability against an external surge using an electronic component having a high allowable voltage, the cost of the component becomes high.
Therefore, the insulation distance between discharge lands where discharge occurs when an external surge of 6 kV is applied to the electric circuit was measured by experiment. As a result, it was confirmed that discharge occurred between the discharge lands when the distance between the discharge lands was 3.0 mm or less. The voltage of the external surge that causes discharge between the discharge lands when the distance between the discharge lands was 3.1 mm was 7 kV.

  Therefore, the insulation distance between the discharge lands is preferably 2.5 mm or more and 3.0 mm or less.

In the above (for example, FIG. 1), the discharge land on the power supply side is provided on the N side of the commercial power supply 101.
This is because the pattern layout of the circuit board 190 is on the N-side pattern of the commercial power supply 101 in order to set the distance between the case connection portion discharge land 193 and the discharge land on the power supply side to 2.5 mm or more and 3.0 mm or less. This is because the pattern layout requires a discharge land on the power supply side (see FIG. 3).
An external surge suppression capacitor 191 is provided on the H side where the distance from the case connection portion discharge land 193 is 2.5 mm or more and 3.0 mm or less and the discharge land cannot be provided.

  That is, when the pattern layout of the circuit board 190 is a pattern layout in which the discharge land on the power supply side needs to be provided on the H side pattern of the commercial power supply 101, the discharge land on the side where the external surge suppression capacitor 191 is provided and the discharge land on the power supply side are arranged. It replaces the installation side.

  The pattern layout is an arrangement of a plurality of partial patterns that constitute the entire pattern of the circuit board 190.

FIG. 6 illustrates a circuit configuration of the lighting device 100 in which the side on which the external surge suppression capacitor 191 is provided and the side on which the power supply side discharge land is provided are interchanged.
In FIG. 6, the external surge suppression capacitor 191 is connected between the N side of the commercial power supply 101 and the light source lighting circuit 120, and is connected in parallel to the diode 112 that flows current from the N side of the commercial power supply 101 to the light source lighting circuit 120. Connected.
The discharge land on the power supply side (power supply H side discharge land 195) is provided on the wiring connected to the H side of the commercial power supply 101.

  The case connection portion 192 is an example of a portion (a portion having the same potential as the ground) connected to the ground. The case connection portion discharge land 193 may be provided on a wire other than the wire connected to the external surge suppression capacitor 191 as long as the wire is connected to the ground.

  Note that the minimum value suitable for the insulation distance (spatial distance or creepage distance) between the discharge lands varies depending on the voltage of the commercial power supply. For example, when the commercial power supply is 200 VAC, the insulation distance between the discharge lands is 2.0 mm or more. When the commercial power source is AC 100V, the insulation distance between the discharge lands may be 1.0 mm or more.

Embodiment 2. FIG.
An embodiment in which an external surge suppression capacitor is provided on both polar sides of the commercial power source 101 and a discharge land on the power source side is provided on both polar sides of the commercial power source 101 will be described.
Hereinafter, items different from the first embodiment will be mainly described. Matters whose description is omitted are the same as those in the first embodiment.

FIG. 7 is a circuit configuration diagram of lighting device 100 according to the second embodiment.
The configuration of the external surge suppression circuit in the second embodiment will be described below with reference to FIG.

  The external surge suppression capacitors (191a, 191b) are connected in parallel to the diode 111 and the diode 112 of the diodes constituting the power supply rectifier circuit 110, respectively.

  Further, discharge lands (194, 195) are provided on both pole sides (N side, H side) of the commercial power source 101.

The insulation distance between the case connection portion discharge land 193 and the power supply N side discharge land 194 and the insulation distance between the case connection portion discharge land 193 and the power supply H side discharge land 195 are both 2.5 mm or more and 3.0 mm or less. It is shorter than the insulation distance between other different poles on 190.
The insulation distance between the case connection portion discharge land 193 and the power supply N side discharge land 194 and the insulation distance between the case connection portion discharge land 193 and the power supply H side discharge land 195 may not be the same.

FIG. 8 is a diagram showing a surge current flow when an external surge is applied to the H side of the commercial power supply 101 in the second embodiment.
The flow of surge current when an external surge is applied between the H side of the commercial power supply 101 and the external surge suppression capacitor 191 will be described below with reference to FIG.

When the voltage of the external surge is larger than the distance between the case connection portion discharge land 193 and the power supply H side discharge land 195, the surge current is discharged between the case connection portion discharge land 193 and the power supply H side discharge land 195 ( Arrow (3)).
When the voltage of the external surge is small with respect to the distance between the case connection portion discharge land 193 and the power supply H side discharge land 195, the surge current is not discharged between the case connection portion discharge land 193 and the power supply H side discharge land 195. The surge current is suppressed by flowing through the external surge suppression capacitor 191a, reaches the power supply N side discharge land 194 via the external surge suppression capacitor 191b, and is discharged from the power supply N side discharge land 194 to the case connection portion discharge land 193 ( Arrows (1) (2)). The distance between the case connection portion discharge land 193 and the power supply N side discharge land 194 is shorter than the distance between the case connection portion discharge land 193 and the power supply H side discharge land 195.

FIG. 9 is a diagram showing a surge current flow when an external surge is applied to the N side of the commercial power supply 101 in the second embodiment.
The flow of surge current when an external surge is applied between the N side of the commercial power supply 101 and the external surge suppression capacitor 191 will be described below with reference to FIG.

When the voltage of the external surge is larger than the distance between the case connection portion discharge land 193 and the power supply N side discharge land 194, the surge current is discharged between the case connection portion discharge land 193 and the power supply N side discharge land 194 ( Arrow (1)).
When the voltage of the external surge is smaller than the distance between the case connection portion discharge land 193 and the power supply N side discharge land 194, no discharge occurs between the case connection portion discharge land 193 and the power supply N side discharge land 194. The surge current is suppressed by flowing through the external surge suppression capacitor 191b, reaches the power supply H side discharge land 195 via the external surge suppression capacitor 191a, and is discharged from the power supply H side discharge land 195 to the case connection portion discharge land 193 ( Arrows (2) (3)). The distance between the case connection portion discharge land 193 and the power supply H side discharge land 195 is shorter than the distance between the case connection portion discharge land 193 and the power supply N side discharge land 194.

FIG. 10 is another example of a circuit configuration diagram of lighting device 100 according to the second embodiment.
As shown in FIG. 10, a plurality of case connection portion discharge lands (193a, 193b) may be provided.
The case connection portion discharge land 193a is provided in a portion facing the power supply H side discharge land 195 in the pattern in which the case connection portion 192 is provided, and the case connection portion discharge land 193b is provided in the pattern in which the case connection portion 192 is provided. Provided in a portion facing the N-side discharge land 194.
The plurality of case connection part discharge lands (193a, 193b) may be provided in different patterns among the plurality of partial patterns constituting the entire pattern of the circuit board 190. The partial pattern in which the case connection portion discharge land is provided is connected to the ground.
By providing a case connection portion discharge land for each discharge land on the power supply side, it becomes easy to discharge an external surge between the discharge lands.

  DESCRIPTION OF SYMBOLS 100 Lighting device, 101 Commercial power supply, 110 Power supply rectifier circuit, 111, 112, 113, 114 Diode, 120 Light source lighting circuit, 130 Light source part, 190 Circuit board, 191, 191a, 191b External surge suppression capacitor, 192, 192a, 192b Case connection part, 193, 193a, 193b Case connection part discharge land, 194 Power supply N side discharge land, 195 Power supply H side discharge land, 200 case, 210 Case bottom, 220 Case top, 230 Screw connection part, 231 screw

Claims (10)

A surge suppression circuit mounted on a circuit board having wiring,
A rectifier circuit having a first diode connected to the first pole of the AC power supply and flowing current from the AC power supply and a second diode connected to the second pole of the AC power supply and supplied current from the AC power supply; ,
A capacitor connected in parallel to the first diode;
A second pole-side land provided in a wiring connecting the second pole of the AC power source and the second diode;
A surge suppression circuit comprising: a ground side land provided in a wiring connected to the ground. The surge suppression circuit according to claim 1, wherein an insulation distance between the second pole side land and the ground side land is 3.0 mm or less. The surge suppression circuit includes the capacitor as a first capacitor,
The surge suppression circuit further includes:
A second capacitor connected in parallel to the second diode;
The surge suppression circuit according to claim 1, further comprising a first pole-side land provided in a wiring connecting the first pole of the AC power source and the first diode. The surge suppression circuit includes the capacitor as a first capacitor, and includes a first ground side land and a second ground side land as the ground side land,
The surge suppression circuit further includes:
A second capacitor connected in parallel to the second diode;
The surge suppression circuit according to claim 1, further comprising a first pole-side land provided in a wiring connecting the first pole of the AC power source and the first diode. The insulation distance between the first pole-side land and the first earth-side land and the insulation distance between the second pole-side land and the second earth-side land are 3.0 mm or less. Item 5. The surge suppression circuit according to Item 4.   The surge suppression circuit according to claim 2 or 5, wherein the insulation distance is 1.0 mm or more.   The surge suppression circuit according to claim 2, wherein the insulation distance is 2.0 mm or more.   6. The surge suppression circuit according to claim 2, wherein the insulation distance is 2.5 mm or more. The surge suppression circuit includes a case connecting portion that is connected to a case that is a case that houses the circuit board and is connected to the ground,
The surge suppression circuit according to any one of claims 1 to 8, wherein the ground side land is provided in a wiring connected to the case connection portion. The surge suppression circuit according to any one of claims 1 to 9,
A lighting device comprising: a lighting circuit that controls a current rectified by the rectifier circuit and lights a light source with the controlled current.

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