JPS6331694Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in air filter control devices.

Conventionally, as an air filter device, for example, the first
As shown in the figure, a band-shaped filter 2 is interposed in the air flow passage A in the housing 1, and both ends of the filter 2 are wound around a feed reel 3 and a take-up reel 4, so that each time the filter 2 becomes dirty, There is one in which the filter 2 is moved step by step by rotating the take-up reel 4.

In this type of device, a light source 5 and its light receiving section (for example, CdS) 6 are respectively disposed with a filter 2 in between, as shown in FIG. Controls the progressive movement of. FIG. 3 shows an example of the configuration of the control circuit. This circuit includes a power supply circuit 10 that creates a predetermined DC voltage from an AC power output (AC20V), a light source abnormality detection circuit 20 that detects abnormalities such as disconnection of the light source 5, and a detection circuit that detects a decrease in the light reception level of the light receiving section 6. Received light level detection circuit 3
0 and a winding motor drive circuit 40. The light source abnormality detection circuit 20 detects a disconnection of the light source using resistors R21, R22, a capacitor C21, and a transistor Tr21, and controls the transistor Tr22 on and off using the detection output.When a disconnection occurs, the indicator lamp 7 is turned off.
I'm trying to make it light up. The light receiving level detection circuit 30 has a series circuit of a transistor Tr31 and resistors R31 and R32 connected in parallel with the light receiving section 6, and this circuit detects an increase in the resistance value of the light receiving section due to a decrease in the light receiving level. The transistor Tr32 is controlled to be turned on or off based on the detection output. Note that resistors R33 and R34 are resistance circuits for setting the detection level, and Tr33 is a transistor for temperature compensation. The winding motor drive circuit 40 has a transistor Tr41 that operates according to the on/off state of the transistor Tr32 of the received light level detection circuit 30, and when the transistor Tr41 is turned on, the winding motor (not shown) is activated.
It is designed to energize the drive control relay Ry.

With this configuration, during steady state, the resistance value of the light receiving section 6 is low, so that the transistor Tr31
and Tr32 are turned off, and as a result, the transistor Tr41 of the winding motor drive circuit 40 is turned off, and no current is supplied to the relay Ry, and as a result, the filter 2 is in a stationary state. In this state, contamination of filter 2 progresses,
When the resistance value of the light receiving section 6 increases to a predetermined value or more, the transistors Tr31 and Tr31 of the light receiving level detection circuit 30
Tr32 is turned on, transistor Tr41 of the winding motor drive circuit 40 is turned on,
As a result, the relay Ry is energized, the take-up motor rotates, and the filter 2 moves step by step. Therefore, the filter 2 is used with contamination always below a certain level. If the light source 5 turns off due to a disconnection or the like during operation, the transistors Tr21 and Tr22 of the light source abnormality detection circuit 20 turn off and on, respectively, and as a result, the indicator lamp 7 lights up to notify that the light source 5 is abnormal. be done. Also, at this time, the transistor Tr of the received light level detection circuit 30
32 is on, but its collector current is bypassed via the diode and the transistor Tr22 of the light source abnormality detection circuit 20, so
Transistor Tr4 of the winding motor drive circuit 40
1 is turned off, the relay Ry does not operate, and therefore the filter 2 does not move step by step.

However, such conventional circuits have the following drawbacks. That is, when the power is turned on, if a sufficient amount of light is not obtained due to a delay in the rise of the light source 5, the received light level detection circuit 30 detects this as a decrease in the received light level at the light receiving section 6, and this causes the winding motor drive circuit to 40 operates and winds up the filter 2.
Furthermore, even if a light source 5 with almost no rise delay is used, the light receiving part 6 such as CdS
Generally, it takes time for the resistance value to stabilize, so during this time the relay of the winding motor drive circuit 40 is
Ry will start working once. Then, the relay
Since Ry has a certain mechanical return time (20 to 30 msec), the motor is driven during about 1 second during this time, and the filter 2 is wound up unnecessarily.

The present invention was developed in view of the above circumstances, and its purpose is to prevent the winding motor from driving when the power is turned on, thereby preventing unnecessary winding of the filter. - To provide a filter control device.

An embodiment of the present invention will be described below with reference to FIGS. 4 and 5. FIG. 4 is a circuit diagram of the air filter control device according to this embodiment, and the same parts as in FIG. 3 are designated by the same reference numerals.

This control device includes a power supply circuit 50 that obtains a DC voltage from an AC power output (AC20V), a light source abnormality detection circuit 60 that detects disconnection of the light source 5, and a light reception level that detects the light reception level of the light receiving section (CdS) 6. It has a detection circuit 70 and a winding motor drive circuit 80 that drives and controls the winding motor of the filter 2,
Furthermore, a delay circuit 90 is interposed between the received light level detection circuit 70 and the winding motor drive circuit 80.

The light source abnormality detection circuit 60 includes resistors R61, R
62, R63, R64 and transistor Tr6
1 detects the presence or absence of current flowing through the light source 5, and when the current is cut off, this is regarded as a break in the light source and the transistor Tr62 is turned on, thereby exciting the relay Ry2 and turning on the light source abnormality indicator lamp (not shown). is lit. Further, the light source abnormality detection circuit 60 divides the collector voltage of the transistor Tr61 using resistors R65 and R66, and outputs this as a light source abnormality detection signal to the winding motor drive circuit 80, which will be described later.

On the other hand, the light receiving level detection circuit 70 includes a variable resistance circuit 71 connected in series to the light receiving section 6, and a transistor that is turned on and off depending on the resistance ratio of the variable resistance circuit 71 and the light receiving section 6, and the Zener voltage of the Zener diode ZD. Tr71, the transistor Tr71 detects an increase in resistance due to a decrease in the level of light received by the light receiving section 6, and the detected output operates the transistors Tr72 and Tr73, respectively. The variable resistance circuit 71 has two resistance circuits that can be selectively selected by a switch SW, and the detection level can be changed by selecting one of these resistance circuits.

Further, the winding motor drive circuit 80 has a logic circuit 81 that performs a logical operation on the detection output of the light reception level detection circuit 70 and the abnormality detection output of the light source abnormality detection circuit 60. The winding motor drive relay Ry1 is configured to operate the winding motor drive relay Ry1 by controlling the transistor Tr81 on and off. For example, as shown in FIG. 5, the logic circuit 81 inverts the abnormality detection output of the light source abnormality detection circuit 60 with a NAND circuit NAND1,
The inverted output and the detection output of the light reception level detection circuit 70 are logically operated by a NAND circuit NAND2, and the calculated output is inverted by a NAND circuit NAND3 and then supplied to the transistor Tr81.

Note that 8 in the figure is a regulator that generates a voltage for driving the logic circuit 81 of the light reception level detection circuit 70 and the winding motor drive circuit 80.

Now, the delay circuit 90 includes a capacitor C91,
This capacitor C91 is composed of a charging resistor R91. Then, the detection output of the output transistor Tr73 in the light reception level detection circuit 70 is delayed by a predetermined time and is supplied to the logic circuit 81 of the winding motor drive circuit 80. Here, the delay time is longer than the rise time of the light source and the light receiving section 6, and is set to, for example, about 1 second.

Next, the operation of the device configured as above will be explained. First, during normal operation, the light receiving level of the light receiving section is high and the resistance value is small, so the transistor
Tr71 is on, and transistors Tr72 and Tr7 are on.
3 are on, and the winding motor drive circuit 80 is supplied with a detection output of "0" level. On the other hand, if the light source 5 is not disconnected,
The transistor Tr61 of the light source abnormality detection circuit 60 is turned on, and as a result, the take-up motor drive circuit 80 is supplied with an abnormality detection output of the "0" level. Therefore, the logic circuit 81 outputs a calculation output of "0" level, and as a result, the transistor Tr81 is turned off and the relay Ry is turned off.
1 is not supplied with current and the winding motor is stopped.

By the way, in this state, when the filter 2 becomes dirty and the light reception level of the light receiving section 6 decreases, its resistance value increases and the base voltage of the transistor Tr71 becomes lower than the Zener voltage, the transistor Tr71 is turned off. Moreover, this turns off the transistors Tr72 and Tr73. Therefore, a detection output of "1" level is supplied to the winding motor drive circuit 80, and as a result, the calculation output of the logic circuit 81 becomes "1" level, turning on the transistor 81, which causes the winding motor to The drive relay Ry1 is excited and the motor is driven. Therefore, the filter 2 is moved step by step to a clean position, after which the device returns to its normal operating state.

On the other hand, when the light source 5 is disconnected due to its lifespan or the like, the transistor Tr61 is turned off and an abnormality detection signal of level "1" is supplied to the winding motor drive circuit 80. Therefore, the output of the logic circuit of the winding motor drive circuit 80 is at the "0" level regardless of the detection output of the light reception level detection circuit 70, the transistor Tr81 is turned off, and the current supply to the relay Ry1 is blocked. , As a result, the winding motor is not driven. That is, unnecessary winding of the filter 2 is not performed.

Now, when the power is turned on, the light source 5 and the light receiving section 6
Due to the delay in the rise of , the received light level detection circuit 70
The transistor Tr71 is once turned off, and the transistors Tr72 and Tr73 are turned off, thereby generating a detection output of the "1" level. However, in the device of this embodiment, the detection output is delayed for a certain period of time by the delay circuit 90. Here, this delay time is set longer than the rise time of the light source 5 and the light receiving section 6. Therefore, the received light level detection circuit 7
The detection output of 0 becomes the "0" level until the "1" level is supplied to the winding motor drive circuit 80, and as a result, the detection output of the "1" level is not supplied to the winding motor drive circuit 80. . Therefore, the transistor of the winding motor drive circuit 80
Tr81 maintains the off state, and as a result, the relay
Since Ry1 is not excited, winding of the filter 2 is not performed either.

As described above, according to this embodiment, the detection output of the light receiving level detection circuit 70 is sent for a certain period of time by the delay circuit 90, so that malfunctions due to a delay in the rise of the light source 5 and the light receiving section 6 when the power is turned on are prevented. Therefore, it is possible to prevent the filter 2 from being sent unnecessarily. Therefore, the filter can be used effectively without waste, and operation costs can be reduced.

Note that the present invention is not limited to the above embodiments. For example, a timer consisting of a programmable counter may be used as the delay circuit. In this way, even if it becomes necessary to change the delay time due to replacement of the light source or light receiving section, or due to aging of the rise characteristic, etc., it can be easily handled. In addition, the configurations of the light reception level detection circuit and the winding motor drive circuit can be modified in various ways without departing from the gist of the present invention.

As detailed above, according to the present invention, a delay circuit is provided that stops the operation of the filter winding mechanism for a certain period of time from the time when it is detected that the light reception level of the light receiving section has decreased below a predetermined value. Accordingly, it is possible to provide an air filter control device that can prevent unnecessary winding of the filter by not driving the winding motor when the power is turned on.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an air filter device, FIG. 2 is a sectional view taken along the - arrow in FIG. 1, and FIG. 3 is a circuit configuration diagram of a conventional air filter control device.
Figures 4 and 5 are for explaining one embodiment of the present invention. Figure 4 is a circuit diagram of an air filter control device, and Figure 5 is a circuit diagram showing a part of the same device. be. 2... Filter, 5... Light source, 6... Light receiving section (CdS), 50... Power supply circuit, 60... Light source abnormality detection circuit, 70... Light reception level detection circuit, 80...
Winding motor drive circuit, 90...delay circuit.

Claims (1)

[Scope of utility model registration request] A light source and its light receiving part are arranged with a windable filter in between, and when the light reception level of the light receiving part falls below a predetermined value, it is determined that the degree of contamination of the filter has progressed, and a mechanism winds up the filter. In an air filter control device configured to wind a certain amount of air filter, the winding mechanism stops the filter winding operation for a certain period of time from the time when it is detected that the light reception level of the light receiving section has decreased to a predetermined value or less. An air filter control device characterized by being provided with a circuit.