JPH01314532A - Dust detector control circuit - Google Patents

Abstract

PURPOSE:To prevent display element from mal-lighting at the start-up of a power source by connecting an emitter of a transistor and a corrector in parallel with a resistor of an integrating circuit, and by connecting No.2 condenser between the base of the transistor and an earth. CONSTITUTION:In an integrating circuit 9 consisting of a resistor 7 and No.1 condenser 8, a transistor 14 is connected in parallel with the resistor 7, and No.2 condenser 15 is connected between the base of the transistor and an earth. At the start-up of a power source, a base electric current flows from an emitter of the transistor 14 toward the base to charge No.2 condenser 15, and a collector electric current flows in proportion to the base electric current between the emitter of the transistor 14 and a collector until the voltage of the base and the emitter drops to less than 0.7V to charge a condenser 8 quickly, so that voltage VC is raised sharply. Therefore, a display element 11 is prevented from mal-lighting because the voltage VC that is input to a comparison circuit 10 is usually raised ahead of the rise of a reference voltage VE.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a dust detection control circuit for detecting dust in a dust collection hose of a vacuum cleaner or the like.

2. Description of the Related Art FIG. 4 shows the configuration of a conventional dust detection control circuit for detecting dust passing through the hose of a vacuum cleaner.

In FIG. 4, reference numerals 21 and 22 indicate a light emitting element and a light receiving element which are arranged facing each other so as to face inside the hose 23. The light emitting element 21 and the light receiving element 22 constitute a dust sensor 24.

The dust sensor 24 transmits light from the light emitting element 21 to the light receiving element 22.
This method utilizes the fact that the output voltage of the light-receiving element 22 changes depending on the amount of light received, and the output voltage V shows the waveform shown in FIG. 6 as dust passes through the hose 23.

When this output voltage V is inputted to the inverting amplifier circuit 26, the output voltage VB has a waveform shown in FIG. 6B.

Furthermore, when the output voltage V of the inverting amplifier circuit 26 is inputted to the integrating circuit 29 composed of a resistor 27 and a capacitor 28 via the diode 26, the output voltage v0 becomes as shown in FIG.
The waveform will be

Then, the output voltage v0 from the integrating circuit 29 is converted to the comparing circuit 3.
0, the comparator circuit 30 outputs the voltage v0 applied by that person.
outputs the H1 signal when the voltage becomes lower than the reference voltage v8,
Also, the voltage V. is the second reference voltage vI'(vl'> v
x”) and fx to output the KLO signal,
The output voltage vl) has a waveform as shown in Fig. 6.

Since this output voltage V is a binary output of Hl and Lo, it is connected to the display element 31 to cause the light emitting element 31 to blink.

In other words, when dust passes through the hose 23, the display element 31
lights up to notify the user of the presence of dust.

However, since the passage time of dust is short, the display element 31 flickers, so the capacitor 28 in the integrating circuit 29 is discharged based on the output voltage V, which is first detected by the dust sensor 24, and vo returns to the original voltage. Time display element 31 until it returns to
It was configured to light up.

Also, the above time is 1 to 48 degrees. and V,
In order to prevent current from flowing from the power supply when the voltage falls at 9 o'clock, the resistor 27 has a high resistance of 1 to 4.7 MΩ, and in order to sharpen the relationship between the discharge current of the capacitor 28 and the terminal voltage, the capacitance is 11 IF. It was configured as

Problems to be Solved by the Invention In the circuit having such a conventional configuration, there was a problem in that the display element 31 erroneously lights up when the power is turned on.

This is the positive terminal voltage V among the input terminals of the comparator circuit 30,
rises at the same rate as the voltage rises, whereas the rise of the - side terminal VC is delayed due to the influence of the resistor 27 and capacitor 28 of the integrating circuit 30 (FIG. 3, dotted line).

Therefore, the + side output terminal voltage v of the comparator circuit 30 increases for X time shown in FIG. 3, and the output voltage V.

becomes l(HIt.

Therefore, when the voltage rises, the display element 31 is erroneously lit even though no dust has passed through it.

In view of the above problems, it is an object of the present invention to prevent erroneous lighting of display elements even when power is turned on.

Means for Solving the Problems In order to achieve the above objects, the present invention includes a dust sensor that detects dust passing through a horn, an amplifier circuit that amplifies the output of the dust sensor, a resistor, and a first capacitor. an integrating circuit configured to integrate a signal from the amplifier circuit;
Comparing means for comparing the signal from the integrating circuit with a reference value, and a display element for displaying the output of the comparing circuit, and the emitter and collector of a transistor are connected in parallel with the resistor of the integrating circuit, and the transistor In this configuration, a second capacitor is connected between the base of the circuit and ground.

Effect With the above configuration, when the power is turned on, while charging the second capacitor from the base of the transistor toward the emitter, the collector current L7 is caused to flow according to the magnitude of the base current L7 to shorten the charging time of the capacitor. This corrects the delay time of the rise of the integrating circuit.

EXAMPLE Below, an example of a dust detection control circuit according to the present invention is shown in FIG.

In FIG. 1, reference numeral 1.2 denotes a light emitting element and a light receiving element which are arranged in facing grooves facing inside the hose 4. The light emitting element 1 and the light receiving element 2 constitute a dust sensor 3.

The output voltage V of the dust sensor 4 shows the waveform shown in FIG. 2 because dust passes through the hose 3.

When the output voltage V is inputted to the inverting amplifier circuit 6, the output voltage V has the waveform shown in FIG. 2B.

Further, when the output voltage V is inputted via the diode e to the integrating circuit 9 composed of the resistor 7 and the first capacitor 8, the output voltage vc has the waveform shown in FIG. 2G.

When the output voltage va is input to the comparison circuit 1o, it is compared with the reference voltages v, , v,' and outputs the waveform of the output voltage vD shown in Fig. 5.

Since the output voltage v, ) is a binary output of Hi and Lo, it is connected to the display element 11 to cause the display element 11 to blink.

In other words, when dust passes through the hose 3, the display element 11 lights up to notify the user of the presence of dust.

When the power is turned on, a base current flows from the emitter of the transistor 14 to the base. This is charged to the second capacitor 16, and the base.

Transistor 1 until the emitter voltage is below 0.7v.
A collector current proportional to the base current is caused to flow between the emitter and collector of the capacitor 8, quickly charging the capacitor 8, and rapidly raising the voltage v0 (FIG. 3, solid line).

Note that under normal conditions, charging of the second capacitor 16 is completed;
The transistor is turned off.

Further, the constants of the resistor 7 and the first capacitor 8 are 1 to 4.7 MΩ and 11 IF, as described in the prior art.

Effects of the Invention As described above, according to the present invention, since the charging speed of the integrating circuit when the power supply is turned on is accelerated by the transistor, it is possible to prevent the display element from being erroneously lit when the power supply is turned on.
This is to reliably notify the user that dust has passed through the hose.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the dust detection control circuit according to the present invention, FIG. 2 is a voltage waveform diagram at each connection point in FIG. 1, and FIG. 3 is a graph showing characteristics at power-on. Fourth
The figure is a circuit diagram showing a conventional dust detection control circuit, and FIG. 5 is a voltage waveform diagram at each connection point in FIG. 4. 3...Dust sensor, 4...Hose, 5
...Inverting amplifier circuit, 9... Integrating circuit,
1o... Comparison circuit, 11... Display element, 14... Transistor, 16... Second capacitor. Name of agent: Patent attorney Toshio Nakao and 1 other person4
ゝ″″9:=Mini-rejection dimension ” to (Nakiri-!
! \)
＼No-sect 2

Claims (1)

[Claims] a dust sensor that detects dust passing through the hose; an amplification circuit that amplifies the output of the dust sensor; an integration circuit that includes a resistor and a first capacitor and integrates the signal from the amplification circuit; Comparing means for comparing the signal from the circuit with a reference value, and a display element for displaying the output of the comparing circuit, and the emitter and collector of the transistor are connected in parallel with the resistor of the integrating circuit, and the base of the transistor and A dust detection control circuit characterized in that a second capacitor is connected between ground.