JPS61151723A - Sensor - Google Patents

Abstract

PURPOSE:To avoid the effect of a pulse drive circuit onto a high sensitive sensor circuit by driving alternately an object element and a dummy element so as to make the load current in the entire pulse drive circuit constant. CONSTITUTION:A drive circuit has a driver A12 driving a load and a driver B12 driving a slave load through which no current flows when a master load has a current flow. The driver B12 drives a load flowing the same current as that of the master load, e.g., a resistor 11. The sum between a current i1 flowing to the master load and a current i2 flowing to the slave load, i1+i2 is a completely constant current when i2=i1, but in general there is an error nearly 10%. The error is 1/10 in comparison with the ripple due to the master load current, which offers a remarkable improvement.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention is a device having a pulse drive circuit and a high-sensitivity sensor circuit, which prevents pulsation of the power supply voltage due to blinking of the pulse drive circuit. The present invention relates to a sensor device that is not affected by a pulse drive circuit.

[Background of the invention]

FIG. 5 shows a conceptual diagram of a sensor circuit to which the present invention is applied. It is composed of a sensor 1, a high-sensitivity sensor amplifier 5, an LED 2, and a driver circuit 4. High sensitivity sensor amplifier...5 and driver circuit...
・4 is on the board...6 and is not supplied with lightning or power from the power source...5. Here, since the pulse drive circuit reduces its load current to 0N10FF, the power supply
Generate a pull. This situation is shown in Figure 6. By pulse-lighting the main load, for example, LED 2, a current of approximately 100 volts is 0N10FF, which increases the resistance of the power supply conductor. . . 7, inductance . . . 8, a voltage drop with the polarity shown in FIG. 2 occurs when the inductance is ON.

This fluctuation in the power supply voltage affects elements in the high sensitivity sensor circuit that are highly dependent on the power supply surface pressure, causing spike-like noise or live pulls in the output of the high sensitivity sensor.

Although this can be improved to some extent by improving the wiring method, route, and ingenuity, it will not lead to a fundamental improvement.

As a method of solving such a power supply ripple problem, a low-pass filter using a capacitor and a coil or a DC stabilizing circuit is provided at the position of stabilizing circuit 9 in FIG. 5. However, although a low-pass filter using a capacitor and a coil can remove IJ-V pull, it is not effective against DC voltage fluctuations. K, which also eliminates DC voltage fluctuations, had no choice but to provide a DC stabilizing circuit using active elements.

When a DC stabilization circuit using active elements is installed, the voltage drop due to the active element is large, so the original voltage cannot be obtained, and furthermore, the energy lost due to the voltage drop becomes heat generation. A rise in temperature occurs within the device. In addition, the DC stabilization circuit using active elements expands the space inside the device.
There are also many drawbacks, such as increased costs.

Note that related devices of this type include, for example,
JP-A No. 56-24620 is mentioned.

[Purpose of the invention]

The object of the present invention is to provide a device having a pulse drive circuit and a highly sensitive sensor circuit, and to prevent the influence of ripples in the power supply voltage caused by the pulse drive of the pulse drive circuit from affecting the highly sensitive sensor circuit, and to use a low-pass filter in the power supply line. By eliminating ripples in the power supply voltage,
The purpose is to prevent the pulse drive circuit from affecting the high-sensitivity sensor circuit.

[Summary of the invention]

In order to prevent the power supply voltage rise caused by the pulse drive of the pulse drive circuit from affecting the highly sensitive sensor circuit, it is common to use a low-pass filter or a shielding plate. When pulse driving the circuit, by driving multiple identical elements or the target element and dummy element alternately, the load current in the entire pulse driving circuit is kept constant and ripples in the power supply voltage are eliminated. It is something.

[Embodiments of the invention]

FIG. 1 shows an embodiment of a pulse drive driver circuit according to the present invention.

This driver circuit is driver A that drives the main load.
・Driver B...12 is provided, which drives a secondary load through which no current flows when current flows through the main load. The driver A...12 drives the main load LED...2 via the resistor...10.

The driver B...12 drives a load, such as a resistor...11, which can flow approximately the same current as the main load. FIG. 2 shows the state of the current flowing through each driver at this time.

8IG is the clock signal of driver A...12,
is the current flowing to the main load, and i2 is the current flowing to the secondary load. i, +i is the sum of the current flowing through the main load and the current flowing through the secondary load. When the current of the secondary load is the same as the current of the main load, i and +i are completely constant currents, but generally they are not completely the same, and an error of about 10 degrees remains. However, compared to the initial ripple caused by the main load current, it becomes '/1o, which is a very significant improvement.

〔Effect of the invention〕

According to the present invention, in a device having a pulse drive circuit and a high-sensitivity sensor circuit, in order to prevent the pulse drive circuit from affecting the high-sensitivity sensor circuit, a low-pass filter for ripple removal is installed on the power supply line. Since there is no need to use a shielding plate for removing induction, the sensor circuit can be made compact and economical, and the high sensitivity sensor circuit can be prevented from being affected by the pulse drive circuit.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a pulse drive circuit according to an embodiment of the present invention, and FIG. 2 is a timing diagram of current flowing through each driver.
FIG. 5 is a conceptual diagram of a sensor device, FIG. 4 is an operational diagram of the sensor device, and FIG. 5 is a conceptual diagram of a sensor device using a known technique. 1...Sensor, 2...LED, 5...Amplifier for high sensitivity sensor, 4...Driver circuit, 5...Power supply, 6
...Circuit board, 7. Conductor resistance, 8. Conductor inductance, 9. Stabilization circuit, 10. Resistance, 1
1...Resistor, 12...Driver. To /7 I ゛) Representative Patent Attorney Akio Takahashi, Figure 1 Figure 2 Figure VJ3

Claims (1)

[Claims] 1. A drive circuit that drives the main load of the pulse drive circuit in a device in which a pulse drive circuit that drives a large current and a high-sensitivity sensor amplifier circuit are operated by being supplied from the same power source;
It has a secondary drive circuit that supplies the load current to the secondary loads so that the overall load current remains approximately constant when the load current of the primary load is cut off, regardless of the state of the load current of the primary load. A sensor device characterized in that the current of the device is constant.