JPH01209696A - Lamp driver - Google Patents

Abstract

PURPOSE:To make it possible to detect filament breakage of a dc lamp with a high sensitivity by connecting terminals of one side of a 1st, 3rd, and 2nd, 4th switch elements respectively to 1st and 2nd terminals, and connecting the other ends of the 1st, 4th and the 2nd, 3rd switch elements respectively to one end and the other end of a wire. CONSTITUTION:When a 1st control signal A is inputted, a 1st and a 2nd switch elements 1, 2 are turned on. When a 2nd control signal B is inputted, 3rd and a 4th switch elements 3, 4 are turned on. When the 1st control signal A is inputted, a current flows from one end of a wire 9 to its other end. When the 2nd control signal B is inputted, a reverse current flows in the wire 9. As a result, an alternate current flows through the wire 9 and a pickup coil 20 detects the current with a high sensitivity without its core being magnetized with a direct current. This arrangement makes it possible to detect a filament breakage by means of the pickup coil with a high sensitivity.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a lamp driver that lights a DC lamp by turning on and off a current supplied to a DC rung at a predetermined cycle, and particularly relates to a lamp driver that lights a DC lamp by turning on and off a current supplied to a DC rung at a predetermined period. This invention relates to a detectable lamp driver.

[Conventional technology] An example of a conventional lamp driver is shown in FIG.

This driver is constituted by a transistor 3o, the collector of which is connected to the terminal 6o, the emitter to the terminal 50, and the base to the terminal 40. Further, one end of a DC lamp 100 configured by connecting LEDs in parallel is connected to the terminal 60, the other end of the lamp 100 is connected to the positive terminal of the power supply, and the terminal 50 is connected to the ground terminal of the power supply. .

Then, when a pulse as shown in FIG. Duty of pulse applied to
It can be changed by changing the ratio. In addition,
Since the pulse repetition period is very short, to the human eye, the rung appears to be constantly lit without blinking.

[Problems to be Solved by the Invention] As a method for detecting breakage of the lamp 100 using such a lamp driver, it is possible to detect the disconnection between the emitter of the transistor 30 and the terminal 5.
A possible method is to attach the pick-up coil 20 to the wiring that connects the wire and detect whether or not current is flowing through this wiring, or to detect the magnitude of the current to determine if the core is broken.

However, in this method, the current flowing between the emitter of the transistor 30 and the terminal 50 flows only in the direction from the emitter to the terminal 50, so the core of the pickup coil 20 is magnetized with direct current, and the sensitivity of the pickup coil is decreases. Therefore, it is important to detect lamp breakage with sufficient sensitivity.

An object of the present invention is to provide a lamp driver that can solve these problems and detect DC lamp breakage with high sensitivity by preventing the core of the pickup coil from being magnetized by direct current. It is in.

[Means for Solving the L Problem] The present invention provides a lamp driver that lights a DC lamp by supplying a current that turns on and off at a predetermined cycle. and a second switching element, third and fourth switching elements that turn on when the second control signal is input, wiring connecting these switching elements, and detecting the current flowing through this wiring, and detecting the result. and a pickup coil that outputs as a result of detecting core breakage of the DC lamp, one terminal of the first and third switch elements is connected to the first terminal, and one terminal of the second and fourth switch element is connected to the first terminal. is connected to the second terminal, and the first
The other terminal of the fourth switch element is connected to one end of the wiring, and the other terminals of the second and third switch elements are connected to the other end of the wiring.

[Operation] This lamp driver is operated by connecting the first terminal to one end of the DC lamp, the other end of the DC lamp to the positive terminal of the power supply, and the second terminal to the ground terminal of the power supply. It is assumed that the first control signal and the second control signal are input alternately.

At this time, when the first control signal is input, the first and second
On the other hand, when the second control signal is input, the third and fourth switch elements are turned on. Therefore, every time the first or second control signal is input, a current flows through the switch element and the rung lights up.

At this time, when the first control signal is input, a current flows in the wiring from the one end to the other end, and on the other hand, when the second control signal is input, the current flows through the wiring. Conversely, current flows from the other end to the one end.

As a result, an alternating current flows through the wiring, and the pickup coil detects the current with high sensitivity without having its core magnetized in a direct current manner. Therefore, if a DC lamp breaks and the current flowing through the wiring changes, that change will be detected with high sensitivity by the pickup coil, and by monitoring the detection result with a voltmeter, for example, a break in the lamp will be reliably detected. It becomes possible to do so.

[Example of this invention] Next, one embodiment of the present invention will be described.

FIG. 1 is a circuit diagram showing an example of a rung driver according to the present invention.

This lamp driver includes transistors 1 to 4 as switching elements and a pickup coil 20 that detects a current flowing through a wiring 9. And transistor 1
．． The collectors of transistors 3 and 3 are connected to terminal 60, and transistor 2
．． The emitters of transistor 4 and transistor 4 are connected to the terminal 50, the emitter of transistor 1 and the collector of transistor 4 are connected to the left end of wiring 9, and the emitter of transistor 3 and the collector of transistor 2 are connected to the right end of wiring 9, respectively. Further, the base of the transistor 1.2 is connected to the terminal 5, and the base of the transistor 3.4 is connected to the terminal 6.

In contrast to the rung driver configured as described above, this is a lamp to be lit by this lamp driver, and 3
DC rung 100 configured by connecting several LEDs in parallel
is connected between the positive terminal of the power supply and the terminal 60, while the terminal 50 is connected to the ground terminal of the power supply. The output of the pickup coil 20 is also supplied to the rectifier circuit 7,
The output is input to an A/D converter 8.

Next, the operation will be explained. Two-phase pulse control signals A and B as shown in FIG. 2 are input to terminals 5 and 6, respectively.

This causes the transistor 1.2 to output the control signal A to logic "1".
The lamp is turned on for a period of '°, current flows through the transistor 1, the wiring 9, and the transistor 2, and the lamp 100 lights up. On the other hand, the transistors 3 and 4 are turned on while the control signal B is at logic "1", current flows through the transistor 3, the wiring 9, and the transistor 4, and the lamp 100 lights up. That is, a current flows and the lamp 100 lights up during a period in which the control signals A and B are at logic "1". The brightness can be changed by changing the duty ratio of the pulse control signals A and B, as in the conventional case.

As described above, when the transistors 1 to 4 turn on/off, a pulse current flows through the wiring 9, and its direction is from left to right when the control signal A is at logic "1'°, and from left to right when the control signal B is at logic "1'°. ”, from right to left. In other words, an alternating current flows through the wiring 9, and the pickup coil 20 detects this alternating current with high sensitivity without its core being magnetized by direct current. is input to the rectifier circuit 7 as an alternating current voltage.The rectifier circuit 7 rectifies this and inputs it to the A/D converter 8.The A/D converter 8 digitizes the input voltage and converts it into a current flowing through the wiring 9. Output as a number representing the value.

Therefore, the magnitude of the current flowing through the wiring 9 can be known with sufficient sensitivity from the numerical value outputted by the A/D converter 8, and when the current value becomes smaller than a predetermined value, the lamp 100 will break. It can be determined that If the current value of the wiring 9 to each LED is measured in advance, it is also possible to know the number of disconnected LEDs from the measured current value at each time.

Note that the A/D converter 8 outputs t i even when an abnormality occurs in the 1-transistor, not when the lamp 100 is broken.
(Since ti changes, this lamp driver can also detect a failure of the driver itself.

[Effects of the Invention] As explained above, the present invention provides a lamp driver that lights a DC lamp by supplying a current that is turned on and off at a predetermined cycle. The first and second switching elements, the third and fourth switching elements that turn on when the second control signal is input, the wiring that connects these switching elements, and the current flowing through these wiring are detected. and a pickup coil that outputs the result as a DC lamp breakage detection result, one terminal of the first and third switch elements is connected to the first terminal, and one terminal of the second and fourth switch element is connected to the first terminal. The terminal is connected to a second terminal, the other terminal of the first and fourth switch elements is connected to one end of the wiring, and the other terminal of the second and third switch element is connected to the other end of the wiring. characterized by being connected.

Therefore, according to the present invention, it is possible to realize a rung driver that can prevent the core of the pickup coil from being magnetized by direct current and detect core breakage of a DC lamp with high sensitivity.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of a lamp driver according to the present invention, FIG. 2 is a timing chart showing control signals input to the same embodiment, and FIG. 3 is a circuit diagram showing a conventional lamp driver. FIG. 4 is a timing chart showing control signals input to the driver. 1 to 4...Transistor, 5.6, 50.60...Terminal, 9...Wiring, 20...Pickup coil. Patent applicant Nippon Signal Co., Ltd. Figure 1 90 and Figure 2 1

Claims (1)

[Claims] In a lamp driver that lights a DC lamp by supplying a current that turns on and off at a predetermined cycle, (a) first and second switches that turn on when a first control signal is input; The device, the third and fourth switching elements that turn on when the second control signal is input, the wiring that connects these switching elements, and the current flowing through these wiring, and the results are used to turn off the DC lamp. (b) one terminal of the first and third switch elements is connected to the first switch element;
one terminal of the second and fourth switch elements is connected to the second terminal, the other terminal of the first and fourth switch element is connected to one end of the wiring, and the second and the other terminal of the third switch element is connected to the other end of the wiring.