JPH0630221B2 - Fluorescent leak detection method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leak detection method for fluorescent lamps, and more particularly to a leak detection method suitable for manufacturing compact fluorescent lamps.

2. Description of the Related Art Recently, various types of compact fluorescent lamps have been put into practical use. One of them is the fluorescent lamp shown in FIG.

This is a straight-tube fluorescent tube 21, 2 with both ends sealed.
2 and 23 and 24 are connected to each other on one end side thereof, and the fluorescent tubes 22 and 23 are connected to each other on the other end side thereof, and further, the other end sides of the fluorescent tubes 21 and 24 are connected to each other. Each of them is provided with an electrode to form an arc tube having one discharge path, and the base 2 is attached to the other end of the arc tube.
5 is attached.

This fluorescent lamp is manufactured, for example, as follows. First, four fluorescent tubes of the same size are prepared. Two of them have electrodes attached to one end, and the other two have no electrodes. A fluorescent tube having an electrode and a fluorescent tube not having an electrode are paired, and each pair is arranged in parallel and connected at the other end side for communication. Further, these two pairs are arranged in parallel, and the fluorescent tubes having no electrodes are connected for communication at one end side. Then, mercury and an inert gas are sealed and sealed in the tube, the base is attached, and the electrode and the base are connected.

Problems to be Solved by the Invention Needless to say, such a fluorescent lamp in which four fluorescent tubes are connected in communication with each other is, of course, a fluorescent lamp in which two fluorescent tubes are connected in communication at one end side of the fluorescent lamp. Compared to the fluorescent lamp described above, not only are there many sealing points but also a communication connection portion for the fluorescent tube is provided, so that a leak defect is likely to occur in the manufacturing process.

The factors are as follows.

(1) A crack or chip in the arc tube of a size that can be easily seen by the operator, which is present in the field of view, (2)
Although there are cracks and cracks in the arc tube of a size that can be easily seen by the operator, those that are outside the field of view, (3) Small cracks and cracks that are extremely difficult for the operator to visually recognize, (4) Poor welding of the sealing portion, (5) cracking of the arc tube and leakage after the exhaust process, and (6) poor welding of the bridge portion.

Of these, the factor (1) can be determined relatively easily by the monitoring operator, so that a defective arc tube can be removed from the manufacturing process whenever it occurs. However, with respect to the other factors (2) to (6), it is very difficult for the observer to visually distinguish them, and leak defects are mostly found in the inspection process.

When a leak occurs in the light emission amount for some reason in the manufacturing process, the defective arc tube is surely and how quickly it is found, and it is eliminated outside the process to improve the yield and reduce the cost. Will be important above. In particular, in the fluorescent lamp with the structure shown in the figure, it is extremely unlikely that two sets of two fluorescent tubes connected in communication are defective products. In order to reduce the manufacturing cost, it is necessary to eliminate the waste of materials and the waste of processing.

In view of the above problems, the present invention aims to provide a method capable of reliably and easily detecting a leak defect of an arc tube and easily applied to an automated manufacturing line.

Means for Solving the Problems A leak detection method for a fluorescent lamp according to the present invention is to introduce a gas into a gas bridge circuit whose one side is a light emitting tube to be inspected, and to detect a pressure difference between the connecting midpoints. In the leak detection method for a fluorescent lamp, which detects the presence or absence of a leak in the arc tube to be tested, the pressure difference detection unit is operated by a cylinder portion in which a permanent magnet is movably housed and a magnetic force. A reed switch, which is connected to both ends of the reed switch with a control device for determining the quality of the light emitting tube to be inspected. The permanent magnet is moved, and the reed switch is operated by the magnetic force of the permanent magnet to operate the control device.

With this structure, when the arc tube to be tested is a non-defective product, the permanent magnet moves within the cylinder portion in which the permanent magnet is movably housed, and the magnetic force of this permanent magnet can operate the reed switch.

Embodiment Hereinafter, an embodiment of the present invention will be described with reference to the drawings showing the configuration of an apparatus.

As shown in FIG. 1, this device includes an electromagnetic valve 1 for supplying a gas having a predetermined pressure only at the time of inspection, a power supply device 2 for operating the electromagnetic valve 1, and an arc tube 3 to be inspected. Leak detection device 4 for detecting the presence or absence of a leak
And a gas filled nozzle 6 for connecting the thin tube 5 of the arc tube 3 to be detected to the leak detection device 4.

The leak detection device 4 constitutes a gas type Wheatstone bridge circuit having the light emitting tube 3 to be inspected as one side, and valves 7, 8 whose fluid resistance value is set to a predetermined value,
A bulb 9 serving as a variable resistance on the opposite side of the arc tube 3 to be inspected, a cylinder portion 10 inserted and connected between the connection intermediate points b and a serving as an output end of the bridge circuit, and the cylinder portion 10
It is housed movably inside and is a permanent magnet (not shown)
And a reed switch 12 that opens when the float 11 is on the connection midpoint a side and closes when the float 11 moves to the connection midpoint b side. The cylinder portion 10, the float 11, and the reed switch 12 constitute a pressure difference detection unit 13.

The cylinder portion 10 is made of a non-magnetic material such as glass, and is arranged such that its central axis is in the vertical direction.

The gas-filled nozzle 6 is provided with a spring mechanism (not shown) for press-contacting the thin tube 5 so that the gas does not leak from this connection portion when the test arc tube 3 is connected to the thin tube 5.

The gas used here may be an inert gas such as nitrogen or argon, or air.

In this device, when the arc tube is not connected, the gas injection nozzle 6 is in an open state, and the resistance value on the opposite side of the bulb 9 is zero. Therefore, the pressure at the connection midpoint a side is substantially atmospheric pressure. be equivalent to. Therefore, the float 11 is still positioned on the connection midpoint a side, and the reed switch 1
2 is off.

When the light emitting tube 3 to be inspected, which is formed by connecting two fluorescent tubes in communication at one end side, comes to a predetermined inspection position and the gas injection nozzle 6 is connected to the thin tube 5, the power supply device 2 operates. Then, the electromagnetic valve 1 is opened, and a gas such as an inert gas such as argon or air is supplied to the leak detection device 4. In this case, when the arc tube is a non-defective product, the pressure on the side of the connection midpoint a increases and the float 11 moves to the side of the midpoint b. The reed switch 12 is turned on by the magnetic force of the permanent magnet of the float 11, and the control device 14 connected to the reed switch 12 determines that the arc tube 3 to be tested is a good product. As a result, the arc tube is sent to the next step.

However, when a leak occurs in the arc tube 3, gas is supplied to the leak detection device 4 through the electromagnetic valve 1. The pressure at the connection midpoint a side does not rise sufficiently. Therefore, the float 11 of the pressure difference detection unit 13 continues to be located on the connection midpoint a side, or the amount of movement is small even if it moves, and the connection midpoint b side, that is, the reed switch 12 is located.
It doesn't reach the part of. Therefore, the reed switch 12 remains off. Therefore, the control device 14 detects that the reed switch 12 is in the off state and generates an output signal indicating that the arc tube under test at this time is a defective fluorescent tube. A defective product removing device (not shown) is arranged in the manufacturing line after the inspection process, and it is operated by this output signal, thereby eliminating the leaking arc tube from the process.

According to this method, since the leak is detected by using the bridge circuit, even if the pressure of the used gas fluctuates, it is canceled between the connection midpoints of the bridge circuit, so that the leak failure of the arc tube is surely ensured. It can also be detected very easily. Therefore, even if it is performed in an unmanned manufacturing line, the reliability of leak detection is very high. If it is carried out after the communication connecting step of the fluorescent tubes, it is possible to determine whether or not the connected state is perfect, and it is possible to prevent defective products from being sent to the subsequent step.

Although the valve is used as the fluid resistance element forming the bridge circuit together with the arc tube to be inspected in the above embodiment, the present invention is not limited to this, and the valve is provided in a fluid pipeline or a pipeline having a predetermined resistance value. Needless to say, it may be a narrowing part.

Advantageous Effects of Invention The leak detection method for a fluorescent lamp of the present invention introduces gas into a gas bridge circuit having one side as a test arc tube, and based on the operation of a pressure difference detection unit connected between the connection midpoints. In the leak detection method for a fluorescent lamp that detects the presence or absence of a leak in the arc tube to be tested, the pressure difference detection unit includes a cylinder unit in which a permanent magnet is movably accommodated, and a reed switch operated by magnetic force, Furthermore, a control device for determining the quality of the light emitting tube to be tested is connected to both ends of the reed switch, and when the light emitting tube to be tested is a non-defective product, the permanent magnet is moved in the cylinder by the pressure in the cylinder portion, Since the reed switch is operated by the magnetic force of the permanent magnet to operate the control device, even if the pressure of the gas used varies, Since this is offset between the connection midpoints, it is possible to reliably and easily determine whether or not a leak has occurred at the sealed portion of the fluorescent tube, the communication connection portion, or the like.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of an apparatus embodying an embodiment of the method of the present invention, and FIG. 2 is a perspective view showing an example of a compact fluorescent lamp. 1 ... Electromagnetic valve, 2 ... Power supply device, 3 ... Arc tube to be tested, 4 ... Leak detection device, 5 ... Thin tube, 13 ... Pressure difference detection unit.

Claims (1)

[Claims] 1. A gas is introduced into a gas bridge circuit whose one side is an arc tube to be inspected, and whether or not there is a leak in the arc tube to be inspected based on the operation of a pressure difference detection unit connected between the connection midpoints. In the method of detecting a leak of a fluorescent lamp, the pressure difference detection unit includes a cylinder unit in which a permanent magnet is movably housed, and a reed switch operated by magnetic force, and the reed switch is provided with the reed switch at both ends thereof. A control device for determining the quality of the light-emitting tube is connected, and when the light-emitting tube to be tested is non-defective, the pressure inside the cylinder moves the permanent magnet in the cylinder, and the magnetic force of the permanent magnet causes the reed switch. Is operated to operate the control device.