JP2000020852A - Photoelectric smoke sensor and method for adjusting sensitivity and method for compensating temperature - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily adjust the sensitivity of a photoelectric smoke sensor, and to easily compensate (control) the temperature characteristics of the photoelectric smoke sensor at the time of manufacturing the photoelectric smoke sensor. SOLUTION: A physical variable detecting part 21 is provided with a light emitting circuit 31 and a light receiving circuit 32 which receives scattered light, due to smoke, of the light emitted from the light emitting circuit 31. In this case, the light emitting circuit 31 is constituted by connecting a switching element and a load resistance with a light emitting element, and when the switching element is a bi-polar transistor, the base voltage is controlled based on control from a CPU 24, and when the switching element is a field effect transistor, the gate voltage is controlled based on control from the CPU 24 so that emission currents can be adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photoelectric smoke detector, a sensitivity adjustment method and a temperature compensation method.

[0002]

2. Description of the Related Art Hitherto, in order to set the sensitivity of a sensor, a volume is adjusted or a circuit constant (for example, a resistance) is selected for each sensor.

The sensitivity of the sensor has a temperature characteristic,
When high-precision detection is required, the temperature characteristics have been corrected using a thermistor or the like to perform temperature compensation.

[0004]

As described above, conventionally, in order to set the sensitivity of a sensor, it is necessary to adjust the volume or select a circuit constant for each sensor. The setting procedure was complicated.

Conventionally, when high-precision detection is required, it is necessary to correct the temperature characteristics using a thermistor or the like in order to perform temperature compensation, which causes a problem that the number of parts and cost increase. Was.

SUMMARY OF THE INVENTION The present invention provides a method for easily adjusting the sensitivity of a photoelectric smoke detector and easily compensating (controlling) the temperature characteristics of the photoelectric smoke detector, particularly in the manufacture of a photoelectric smoke detector. It is an object to provide a possible photoelectric smoke detector, a sensitivity adjustment method and a temperature compensation method.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a physical quantity detecting section for detecting a smoke density as a physical quantity and converting it into an electric signal (analog signal); An A / D converter for converting an analog signal output from the unit into a digital signal, a CPU for controlling the entire sensor, a non-volatile memory, and a transmission line between a predetermined device connected to the transmission line. At least a communication unit that performs transmission via
A light-emitting circuit and a light-receiving circuit that receives scattered light due to smoke or the like of light emitted from the light-emitting circuit are provided, and the light-emitting circuit is configured by connecting a switching element and a load resistor to a light-emitting element, When the switching element is a bipolar transistor, the base voltage is controlled based on the control from the CPU. When the switching element is a field effect transistor, the gate voltage is controlled by the CPU. By controlling based on
It is characterized in that the emission current can be adjusted.

According to a second aspect of the present invention, there is provided a physical quantity detecting section for detecting smoke density as a physical quantity and converting the same into an electric signal (analog signal), and converting an analog signal output from the physical quantity detecting section into a digital signal. An A / D converter, a CPU for controlling the entire sensor, a non-volatile memory, and a communication unit for performing transmission via a transmission line between a predetermined device connected to the transmission line. The physical quantity detection unit is provided with a light emitting circuit and a light receiving circuit that receives scattered light due to smoke or the like of light emitted from the light emitting circuit, and the light emitting circuit includes a light emitting element, a switching element, a load resistance, and the like. Are connected, the load resistance is variable,
The emission current can be adjusted by controlling the resistance value of the load resistor based on control from the CPU.

According to a third aspect of the present invention, there is provided a sensitivity adjusting method for adjusting the sensitivity of the photoelectric smoke sensor according to the first or second aspect, wherein the method comprises the steps of: With the predetermined device, the emission characteristics of the sensor with respect to the smoke density were measured using the emission current of the sensor as a parameter, and the emission current that gave the maximum output value within the range not saturated at the maximum used smoke density was determined and determined. It is characterized in that the detector sensitivity is adjusted so that the light emitting circuit is controlled by the light emitting current.

According to a fourth aspect of the present invention, in the sensitivity adjusting method according to the third aspect, the emission current determined by an external predetermined device is stored in a non-volatile memory of the sensor, and is stored in the non-volatile memory. The stored emission current is
It is characterized by being referred to by the CPU and used for controlling the light emission current.

According to a fifth aspect of the present invention, there is provided a temperature compensation method for compensating the temperature characteristic of the sensitivity of the photoelectric smoke sensor according to the first or second aspect, wherein a bipolar transistor is used as a switching element. When the sensor is manufactured, the emitter voltage value at each of the plurality of base voltage values is measured by an external predetermined device at the time of manufacture of the sensor, and the base voltage corresponding to the emitter voltage that reduces the temperature characteristic from the measured emitter voltage value is measured. By calculating a voltage value and operating the switching element with the base voltage value, the temperature characteristic of the sensor sensitivity is compensated.

According to a sixth aspect of the present invention, in the temperature compensation method according to the fifth aspect, the base voltage value determined by an external predetermined device is stored in a non-volatile memory of the sensor. Is characterized in that a temperature characteristic of a sensor sensitivity is compensated by applying a base voltage stored in a nonvolatile memory to a base of a bipolar transistor.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration example of a photoelectric smoke detector according to the present invention. Referring to FIG. 1, the sensor 2 includes a physical quantity detection unit 21 that detects smoke density as a physical quantity and converts the smoke density into an electric signal (analog signal), and converts an analog signal output from the physical quantity detection unit 21 into a predetermined cycle. A / D converter 22 that samples and converts it into a digital signal
A CPU 24 for controlling the entire sensor such as an abnormality (for example, fire) determination; a ROM 25 storing a control program of the CPU 24; a RAM 26 used as various work areas, etc .; A communication unit that performs transmission via the transmission path 3 between the non-volatile memory 27 in which the information is stored and a predetermined device (for example, a receiver or an adjustment jig) connected to the transmission path 3
(Communication interface unit) 29.

In the example shown in FIG. 1, when the photoelectric smoke detector 2 is manufactured, a predetermined device 1 is connected to the transmission line 3 in order to adjust its sensitivity and to compensate (control) its temperature characteristics. Shows a state where the adjustment jig is connected.

In the sensor 2 shown in FIG. 1, the physical quantity detector 21 is provided with a light emitting circuit 31 and a light receiving circuit 32 for receiving light scattered by smoke emitted from the light emitting circuit 31 or the like. .

FIG. 2 is a diagram showing a configuration example of the light emitting circuit 31 and the light receiving circuit 32. The light emitting circuit 31 emits light from the light emitting element 33 such as a light emitting diode and the light emitting current of the light emitting element 33 based on a command from the CPU 24. Emission current control unit 34 to be controlled
And The light receiving circuit 32 uses a light receiving element 35 that receives light and converts the light into an electric signal. The output (analog signal) from the light receiving element 35 is converted into a digital signal by the A / D converter 22. Then, it is sent to the CPU 24.

FIGS. 3A and 3B are diagrams showing an example of the configuration of the emission current control unit 34. FIG. FIG. 3A shows an example of a configuration in which a bipolar transistor is used, and FIG. 3B shows an example of a configuration in which an FET (field effect transistor) is used. The light emitting circuit 31 is generally configured by connecting a switching element (for example, a transistor) 41 and a load resistor 42 to a light emitting element 33. When the switching element 41 is a bipolar transistor, its base voltage V _B
Is controlled by the current control circuit 43 based on the control from the CPU 24, and the switching element 41
If it is ET (field effect transistor), by controlling the current control circuit 43 based on the gate voltage V _G to the control from the CPU 24, it can be adjusted emission current I _L. Alternatively, the load resistor 42 and a variable, the resistance value of the load resistor 42 and controls the current control circuit 43 under the control of the CPU 24, can be adjusted emission current I _L.

More specifically, in the case of the configuration shown in FIG. 3A (in the case of using a bipolar transistor),
The emission current _IL is obtained by the following equation.

[0019]

## EQU1 ## I _L = V _E / R _L = (V _B -V _BE ) / R _L

Here, V _E is the emitter voltage, V _B is the base voltage, V _BE is the base-emitter voltage, and _RL is the resistance of the load resistor 42. As can be seen from Equation 1, the light emission current I _L can be adjusted by variably controlling V _B or R _L.

[0021] Figure 4 is a current control circuit 4 for variably controlling V _B
FIG. 5 is a diagram illustrating a specific example of a current control circuit 43 that variably controls R _L.

The light emitting current I _L defines the amount of light emitted from the light emitting element 33. The larger the light emitting current I _L is set, the larger the amount of light emitted from the light emitting element 33 becomes.

FIG. 6 shows that the light emission currents (light emission amounts) I _L are I _L1 , I _L2 , I _L3 , I _L4 , I _L5 , I _L6 , I _L7 , I _{L8, respectively.}
FIG. 6 is a diagram illustrating characteristics of the physical quantity detection unit 21 when the setting is set to. That is, the light emission current (light emission amount) of the light emitting circuit 31
When light is emitted by the light emission amount of the light emitting element 33 by setting the I _L to a predetermined one, shows the relationship between the output from the light receiving element 35 of the light receiving circuit 32 for the smoke density (% / m) (analog value) ing. As can be seen from FIG. 6, the light emission current (light emission amount) I
Changing _L changes the smoke density-analog value characteristic.

In the example of FIG. 6, it is assumed that the detector can be used up to a smoke density of 15% / m. In I _L5 ~I _L8 15% /
The analog value at m is the capability of the A / D converter 22 (“FF”)
And the light emission current (light emission amount) I _{L that} is optimal to use is the remaining light emission current (light emission amount) I _{L1 to} I _L4.
Will be selected in the range. As the amount of light emission increases, the resolution of one step of the analog value increases, which is suitable for high-accuracy (high sensitivity) detection. Therefore, in this example, the light-emitting current _IL4 with the largest amount of light emission is preferably used.

As described above, in the example of FIG.
As the light emission current (emission amount) I _L is I _L4, well being controlled by the current control circuit 43, in the present invention, such a sensitivity adjustment procedure at the time of manufacture of the sensor, FIG. 1 As shown, the adjustment can be performed using an adjustment jig 1 as an external predetermined device.

FIG. 7 is a flowchart showing a processing operation procedure of the adjusting jig 1 when adjusting the sensitivity of the photoelectric smoke detector 2. Referring to FIG. 7, during manufacturing, first,
Free environment photoelectric smoke detector 2 is smoke (smoke concentration environment 0% / m) placed, in this state, the jig 1 to sensor 2, all the light emission current (emission amount) I _L Send instructions in sequence. Specifically, for example, the emission current _IL is sequentially changed to I _L1 ,
A command to send I _L2 , I _L3 , I _L4 , I _L5 , I _L6 , I _L7 , I _L8 is sent. Upon receiving this command from the jig 1, the CPU 24 of the sensor 2 sets the light emission current control unit 34 to I _L1 , I _L2 ,
I _L3 , I _L4 , I _L5 , I _L6 , I _L7 , I _L8 are controlled to control the light emitting element 33 to I _L1 , I _L2 , I _L3 , I _L4 , I _L5 , I _L
Light emission is sequentially performed with light emission currents (light emission amounts) of _L6 , _IL7 , and _IL8 . In the light receiving element 35, the light emitting current from the light emitting element 33
(Emission) I _L1 , I _L2 , I _L3 , I _L4 , I _L5 , I _L6 , I _L7 ,
The scattered light due to the light emission at _IL8 is sequentially received and output as an analog signal. Light emission current (light emission amount) I _L1 , I
The analog signal from the light receiving element 35 output corresponding to each of _L2 , I _L3 , I _L4 , I _L5 , I _L6 , I _L7 , and I _L8 is converted into a digital signal by the A / D conversion unit 22, CP
After being given to U24, it is sent to jig 1 and taken into jig 1. Thus, in the jig 1, when the photoelectric smoke detector 2 is placed in an environment where there is no smoke (an environment where the smoke density is 0% / m), all the emission currents (light emission amounts) I _L1 , I _{L L2} , I _L3 , I
_The output of the light receiving circuit at _L4 , _IL5 , _IL6 , _IL7 , _IL8 can be measured (step S1).

Next, the photoelectric smoke detector 2 is set to smoke of a predetermined density.
(Smoke for adjustment) is placed in an environment (in a smoke box for sensitivity adjustment with a smoke density of, for example, 10% / m). In this state, the jig 1 sends all the light emission currents (light emission) to the sensor 2. The command for the quantity) I _L is sent sequentially. Specifically, for example, the light emission current I _L to successively _{I L1, I L2, I L3} , I L4, I L5, I L6, I L7, I L8
Is sent. When this command is received from jig 1,
The CPU 24 of the sensor 2 sets the emission current control unit 34 to I _L1 ,
The light emitting element 33 is controlled to be I _L2 , I _L3 , I _L4 , I _L5 , I _L6 , I _L7 , I _L8, and the light emitting element 33 is set to I _L1 , I _L2 , I _L3 , I _L4 ,
_{I L5, I L6, I L7} , the light emission current (emission amount) of I _L8 in to sequentially emit light. In the light receiving element 35, the light emission current (light emission amount) I _L1 , I _L2 , I _L3 , I _L4 , I _L5 , I _L6 , I _L from the light emitting element 33
_The scattered light due to the light emission at _L7 and _IL8 is sequentially received and output as analog signals. Light emission current (light emission amount)
An analog signal from the light receiving element 35 output corresponding to each of I _L1 , I _L2 , I _L3 , I _L4 , I _L5 , I _L6 , I _L7 , and I _L8 is converted into a digital signal by the A / D converter 22. Converted,
After being given to the CPU 24, it is sent to the jig 1 and taken into the jig 1. Thus, in the jig 1, when the photoelectric smoke detector 2 is placed in an environment where smoke of a predetermined concentration (smoke for adjustment) is present, all the light emission currents (light emission amounts) I _L1 , I _L2 , I _L3 ,
It is possible to measure the light receiving circuit output at _{I L4, I L5, I L6} , I L7, I L8 ( step S2).

As described above, in the jig 1, when the photoelectric smoke detector 2 is placed in an environment where there is no smoke (environment where the smoke density is 0% / m), the photoelectric smoke detector 2 is placed at a predetermined density. All light emission currents (light emission amounts) I _L1 , I _L2 , I when placed in an environment where smoke (smoke for adjustment) is present (in a smoke box for sensitivity adjustment with a smoke density of 10% / m)
The light receiving circuit outputs at _L3 , I _L4 , I _L5 , I _L6 , I _L7 , and I _L8 were obtained, and based on these data, the jig 1 inside the jig 1 as shown in FIG. Is measured. That is, the light emission current (light emission amount) of the light emitting circuit 31 is changed to I _L1 , I _L2 , I _L3 , I _L4 , I _L5 , I _L , respectively.
_When the light-emitting element 33 emits light at the light emission amount by setting the light-emitting element 33 to _L6 , _IL7 , and _IL8 , the output (analog value) of the light-receiving circuit 32 with respect to the smoke density (% / m) is obtained. The relationship has been measured.

Next, in the jig 1, from the measurement results of FIG. 8, all the light emission currents (light emission amounts) I _L1 , I _L2 , I _L3 , I _L4 ,
The light receiving circuit output for the maximum used smoke density (15% / m in the example of FIG. 8) at I _L5 , I _L6 , I _L7 , and I _L8 is calculated (step S3). In the example of FIG. 8, the light emission current (light emission amount) I _L1 ,
I _L2, I _L3, the maximum light receiving circuit outputs for use the smoke density (15% / m) in the _{I L4, I L5, I L6} , I L7, I L8, O
_M1 , _OM2 , _OM3 , _OM4 , _OM5 , ... are calculated.

As described above, the light emission current (light emission amount) I _L1 ,
_{I L2, I L3, I L4} , I L5, I L6, I L7, when calculating the light receiving circuit outputs to the maximum use smoke density (15% / m) in the I _L8, the jig 1, maximum use smoke density receiving circuit output for (15% / m) is not saturated (in the example of FIG. 8, does not exceed "FF") maximum emission current (emission amount) is determined I _L (step S4). In the example of FIG. 8, the maximum smoke density (15% /
m), the light emission current (light emission amount) at which the output of the light receiving circuit does not saturate (does not exceed “FF”) is I _{L1 to} I _L4 .
Of these, the emission current that gives the maximum light receiving circuit output _OM4
(Light emission amount) I _L4 is determined as the maximum light emission current (light emission amount).

Thus, the maximum light emission current (light emission amount)
When I _L4 is determined, the jig 1 _adjusts the calibrated smoke density at the determined light emission current (light emission amount) I _L4 (10% / m in the example of FIG. 8).
Calculating the light receiving circuit output O ₄ for (step S5).

The jig 1 determines the light emission current (light emission amount) I _L4 and the light receiving circuit output O ₄ for the calibrated smoke density (10% / m) at the determined light emission current (light emission amount) I _L4. Is transmitted to the sensor 2, and these are stored in the nonvolatile memory 2 of the sensor 2.
7 (step S6). Thereby, the detector 2
After that, the CPU 24 of the sensor 2
The determined light emission current (light emission amount) I _L4 stored in the nonvolatile memory 27 and the light receiving circuit output O ₄ for the calibrated smoke density (10% / m) at the determined light emission current (light emission amount) I _L4 are used. Control the light emission current control unit 34 (current control circuit 43),
The sensitivity characteristic of the physical quantity detection unit 21 is set. More specifically, the sensitivity-adjusted sensor 2 is turned on when the power is turned on.
The light emission current (light emission amount) stored in the nonvolatile memory 27 is read, and the light emission amount is determined. In the above example, the emission current
Since the (light emission amount) I _L4 is stored, the light emitting operation is performed with the light emission amount I _L4 . In this state, the analog value read from the light receiving circuit 32 is converted into smoke density using the calibration data O ₄ stored in the nonvolatile memory 27.

As described above, the sensitivity of the sensor 2 is adjusted by the jig 1. As can be seen from the above description, since a series of sensitivity adjustment operations are performed by software processing (software processing in the jig 1), a conventional technique in which an operator adjusts the volume and adjusts the sensitivity of the sensor. Significant labor savings are possible as compared to the adjustment method.

[0034] Note that (if that is the arrangement example of FIG. 3 (a)) when the bipolar transistor is used in the switching element, when the V _B sufficiently larger than V _BE, the temperature of the light emission current I _L depends The sensitivity of the sensor can be adjusted by controlling the light emission current by the CPU 24. Further, if the FET is used for the switching element (the case of the configuration example of FIG. 3 (b)), the temperature dependence of the V _GS is small, without a gate voltage V _G is sufficiently greater than V _GS, Similar effects can be obtained. However, in this case, a temperature characteristic of sensitivity is generated, and other temperature compensating means is required.

Since the light emitting / receiving element has a temperature characteristic (temperature dependency), it is necessary to control the temperature characteristic of the sensor sensitivity. In the present invention, the temperature characteristic of the switching element 41 is utilized. I do it. The control of the temperature characteristics of the sensor sensitivity can also be performed using the jig 1. Next, such control of the temperature characteristic of the sensor sensitivity will be described in detail. As the switching element 41 having the temperature characteristic, there is a bipolar transistor.
Let 1 be a bipolar transistor.

[0036] In this case, in the present invention, in order to compensate for the temperature characteristics of the sensor sensitivity, so that to adjust the emitter voltage V _E of the switching element 41 (a bipolar transistor).

The temperature characteristic of the sensitivity of the sensor generally has a high sensitivity at a low temperature and a low sensitivity at a high temperature, due to the characteristics of the light emitting and receiving elements and the like. Now, when temperature compensation is not performed as the sensor 2, in the range of −10 to 50 ° C.,
It is assumed that the temperature characteristic is ± 20% with reference to 20 ° C. This temperature characteristic is based on the light receiving element 35 and the light emitting element 33.
Greatly affects the temperature characteristic of the light emitting device. When the temperature rises, the light emission amount of the light emitting element 33 decreases, so that the smoke density instruction value of the sensor decreases. For example, as shown in FIG.
Correct value in ° C (correct detector indicating smoke concentration 10% /
m) when used in an environment of −10 ° C., the true value of smoke density of 10% / m becomes 12% / m. When used in an environment of 50 ° C., the true value of smoke density of 10% / m becomes 10% / m. 8% / m. When a bipolar transistor having a temperature characteristic is used for the switching element 41, in order to compensate for such a temperature characteristic of the sensor sensitivity, in the present invention,
And so as to adjust the emitter voltage V _E of the bipolar transistor.

Now, the switching element 4 of the light emitting circuit 31
1 has a Darlington transistor (the temperature characteristic of V _BE is about-
If two 2 mV / ° C. transistors (bipolar transistors are used) are used, the temperature characteristic of V _BE is about −4.
mV / ° C. The current I _L (20 ° C.) flowing through the light emitting element 33 at 20 ° C. is obtained by the following equation.

[0039]

## EQU2 ## I _L (20 ° C.) = V _E (20 ° C.) / R _L = (V _B −V
_BE (20 ° C)) / R _L

At this time, the emission current I _L (50 ° C.) at 50 ° C. is increased by 20% in order to compensate for the above temperature characteristics. The emission current I _L (50 ° C.) at 50 ° C. is obtained by the following equation. Here, the temperature characteristics of V _B and R _L are sufficiently smaller than the temperature characteristics of V _{BE and} are ignored.

[0041]

I _L (50 ° C.) = V _E (50 ° C.) / _RL = (V _B −V _BE (50 ° C.)) / R _L = [V _B − (V _BE (20 ° C.) + ΔV _BE ( 50-20 ° C))) / R _L

Here, ΔV _BE (50-20 ° C.) is a temperature change of V _{BE when} the temperature changes from 20 ° C. to 50 ° C., and is −4 mV /
It has a rate of change of ° C. In this case, ΔV _BE (5
0-20 ° C) is 0.12V.

Assuming that I _L (50 ° C.) is compensated for by 20% of I _L (20 ° C.), the following equation holds.

[0044]

I _L (20 ° C.) × 1.2 = I _L (50 ° C.) (V _B −V _BE (20 ° C.)) × 1.2 = V _B −V _BE (50 ° C.) = V _B − _{(V BE (20 ℃) +} ΔV BE (50-20 ℃)) V E (20 ℃) × 1.2 = V E (20 ℃) + 0.12V V E (20 ℃) × 0.2 = 0.12V V _E (20 ° C.) = (0.12 / 0.2) V = 0.6V

From equation (4), V _E at 20 ° C. is 0.6 V
, The emission current I _L (50 ° C.) at 50 ° C. becomes 20
%, And it can be seen that the temperature characteristic of the sensor can be offset by -20%. Further, when the V _E at 20 ° C. to 0.6V, even at -10 ° C. emission current I _L (-
10 ° C.) is reduced by 20%, which can be offset with the temperature characteristic of the sensor of 20%. Thus, the emitter voltage V _E
To 0.6V and temperature-compensated detector indicated smoke density
(Light receiving circuit output) is as shown in FIG.

FIG. 11 is a diagram showing a configuration example of the sensor 2 for realizing the compensation of the temperature characteristic of the sensor sensitivity as described above. In this case, also in this case, the entire configuration of the sensor 2 is as follows.
The configuration shown in FIG. 1 may be used. Referring to FIG. 11, this detector 2
Then, the switching element 41 (bipolar transistor)
The emitter voltage V _E at 20 ° C. as described above (for example, 0.6V) to the control, the switching element 4
A base voltage (V _B ) control means 45 for controlling the base voltage V _B of 1 (bipolar transistor) is provided. That, CPU 24 of the sensor 2, under instruction from the adjustment jig 1 reads the emitter voltage V _E when changing the base voltage V _B to the various, applied to the jig 1, the jig In 1, a base voltage value V _B corresponding to an emitter voltage value V _E (0.6 V in the above example) for minimizing the temperature characteristic (temperature dependency) is determined from these measurement data, and this base voltage value is determined. It gives V _B to sensor 2, sensor 2
Is stored in the non-volatile memory 27.
When the base voltage value V _B is set in the nonvolatile memory 27 in this way, the CPU 24 sets the base voltage V _B of the switching element 41 to the nonvolatile memory 27.
Is controlled by the base voltage (V _B ) control means 45 so that the base voltage value is stored in the base voltage value V _B. by this,
The switching element 41 has an emitter voltage _VE of 0.6
V can be set. The value of this way, the normal V _E is 0.
By adjusting the V _B so as to 6V, it is possible to compensate for the temperature characteristics of the sensor sensitivity. Incidentally, the base voltage (V _B) control means 45, for example, the configuration similar to that of FIG. 4, and, by the function of monitoring the emitter voltage V _E, can be realized.

FIG. 12 is a flowchart showing a processing operation procedure of the adjusting jig 1 when compensating for the temperature characteristic of the sensitivity of the photoelectric smoke detector 2. Referring to FIG. 12, at the time of manufacture, first of all, when the command for sequentially changing the base voltage V _B to measure the emitter voltage V _E is transmitted to the detector 2 from the jig 1, sensor 2 CPU24 of, sequentially changing the base voltage V _B, to measure the emitter voltage V _E at that time, transmitting the emitter voltage values measured in correspondence with the respective base voltages to jig 1 (step S11).

In the jig 1, of the measured emitter voltage values, the emitter voltage value (0.6
Determine the base voltage V _B corresponding to the nearest emitter voltage) to V (step S12).

In this way, when the base voltage value V _B corresponding to the emitter voltage value (emitter voltage value closest to 0.6 V) for reducing the temperature characteristics is determined, the jig 1
Transmits the determined base voltage value V _B to the sensor 2 and stores it in the nonvolatile memory 27 of the sensor 2 (step S13). Thereby, the CPU 24 of the sensor 2
The base voltage (V _B ) control means 45 controls the base of the switching element 41 to apply the voltage of the base voltage value V _B stored in the non-volatile memory 27, whereby the emitter voltage V _{E of the} switching element 41 is controlled. Can be set to 0.6V. In this manner, the value of V _E at the normal time to adjust the V _B so as to 0.6V, it is possible to compensate for the temperature characteristics of the sensor sensitivity.

After the compensation process of the temperature characteristic of the sensor sensitivity is performed in this way, the sensitivity adjustment process as shown in FIG. 7 is performed (step S14). In this case, since the compensation processing of the temperature characteristic of the sensor sensitivity is performed, the sensitivity adjustment can be performed in the sensitivity adjustment processing while minimizing the influence of the fluctuation due to the temperature.

[0051] Incidentally, the temperature compensation process, more specifically, as the base voltage V _B, assuming the base voltage value V _B0 ~V _B7 of 8 stages for example, each of the base voltage V _B0
The emitter voltages V _{E0 to} V _E7 are measured for V _B7 to V _B7 . At this time, the measurement of the emitter voltages V _{E0 to} V _E7 is performed by the CPU.
No other measuring device is required since the measurement can be performed at 24.

Next, from the measured V _{E0 to} V _E7 , the temperature characteristics
Determining the base voltage V _B corresponding to the emitter voltage for less (temperature dependence). In the above example, V _E is 0.6
A base voltage value V _B that is closest to V is determined. Then, the determined base voltage V _B is stored in the nonvolatile memory 27, performs the sensitivity adjustment procedure.

As described above, in the temperature compensation process and the sensitivity adjustment process of the sensor sensitivity, the sensitivity adjustment jig 1 is prepared, and the operation of the sensor 2, the calculation process, and the setting to the nonvolatile memory are performed by the jig 1. And within the detector 2
CPU 24 (software processing) under the control of the temperature characteristics, the sensitivity adjustment control is performed, in the detector 2, may without any providing a special measuring instrument or the like (for example, to observe the V _E in such a voltmeter You don't have to.) That is, according to the present invention, it is possible to perform the temperature characteristic compensation and the sensitivity adjustment of the sensor sensitivity without complicating the configuration of the photoelectric smoke sensor 2 (without increasing the size).

In the above description, the CPU 24 uses the data stored in the nonvolatile memory 27 to perform sensitivity adjustment control,
Although the temperature compensation control is performed, the data stored in the nonvolatile memory 27 is actually loaded into the RAM 26, and the CPU 24 uses the data loaded into the RAM 24 to perform sensitivity adjustment control and temperature compensation control. Is to be performed. At this time, storing the data determined from the jig 1 in the non-volatile memory 27 instead of the RAM 24 first prevents the data loaded in the RAM 26 from being lost when the power is turned off. This is to prevent it. That is, the data determined from the jig 1 is stored in the RAM
24, instead of being stored in the non-volatile memory 27 first, when the power is turned off, when the power is turned on, or at the time of resetting,
This is because data stored in the non-volatile memory 27 without being lost can be loaded into the RAM 26, set, and used.

That is, the sensor 2 reads data stored in the non-volatile memory 27 at the time of power-on or reset, and loads the data into the work area on the RAM 26. Even if the data on the RAM 26 is lost due to the interruption, the data stored in the non-volatile memory 27 is stored in the non-volatile memory 27.
By loading the data into the RAM 26, the sensor 2 can be operated with the same data as before the power was turned off.

Further, for example, when writing data to the nonvolatile memory 27, a writing flag indicating that writing is in progress is set, and the data is repeatedly and sequentially written to a plurality of areas of the nonvolatile memory 27, and the written contents are verified. ,
If it is normal, the operation of resetting the writing flag is performed for a plurality of areas of the nonvolatile memory 27. When the power is turned on, the writing flag is checked. Control may be performed such that data written in another area of the memory 27 is adopted. When such control is performed, even if the power is shut off while data is being written to the nonvolatile memory 27, correct data is identified by checking the writing flag and used. be able to.

[0057]

As described above, according to the first, second, third, and fourth aspects of the present invention, the light emission current is controlled by the CPU. There is no need to adjust the volume or select a resistor, and it is possible to save labor in manufacturing.

According to the first, second, fifth, and sixth aspects of the present invention, the temperature characteristics of the sensor sensitivity can be compensated for without using a component such as a thermistor.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a photoelectric smoke detector according to the present invention.

FIG. 2 is a diagram illustrating a configuration example of a light emitting circuit and a light receiving circuit.

FIG. 3 is a diagram illustrating a configuration example of a light emission current control unit.

[4] The V _B is a diagram showing a specific example of the current control circuit for variably controlling.

FIG. 5 is a diagram illustrating a specific example of a current control circuit that variably controls R _L.

FIG. 6 shows that light emission current (light emission amount) I _L is I _L1 and I _L1 , respectively.
It is a figure which shows the characteristic of the physical-quantity detection part when it is set to _L2 , _IL3 , _IL4 , _IL5 , _IL6 , _IL7 , _IL8 .

FIG. 7 is a flowchart illustrating a processing operation procedure of the adjustment jig when adjusting the sensitivity of the photoelectric smoke detector.

8 is a diagram for explaining the process to determine the optimal emission current (emission amount) I _L.

FIG. 9 is a diagram illustrating an example of a temperature characteristic of a sensor sensitivity.

FIG. 10 is a diagram illustrating an example of compensation for the temperature characteristic of the sensor sensitivity.

FIG. 11 is a diagram illustrating a configuration example of a sensor for realizing compensation of the temperature characteristic of the sensor sensitivity.

FIG. 12 is a flowchart illustrating a processing operation procedure of the adjusting jig when compensating for the temperature characteristic of the sensitivity of the photoelectric smoke detector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Predetermined apparatus (receiver or jig) 2 Sensor 3 Transmission path 21 Physical quantity detection part 22 A / D conversion part 24 CPU 25 ROM 26 RAM 27 Non-volatile memory 29 Communication part 31 Light emitting circuit 32 Light receiving circuit 33 Light emitting element 34 Light emitting Current control unit 35 Light receiving element 41 Switching element 42 Load resistance 43 Current control circuit 45 Base voltage control means

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G059 AA05 CC19 DD16 EE02 MM09 MM10 MM14 5C085 AA03 AB01 AC13 BA33 CA07 DA04 DA16 DA18 EA38

Claims (6)

[Claims] An electric signal obtained by detecting smoke density as a physical quantity.
(Analog signal) a physical quantity detector, an A / D converter for converting an analog signal output from the physical quantity detector into a digital signal, and a CPU for controlling the entire sensor
And a non-volatile memory, and at least a communication unit that performs transmission via the transmission line between a predetermined device connected to the transmission line, and the physical quantity detection unit includes a light emitting circuit and a light emitting circuit. A light receiving circuit for receiving scattered light due to smoke of emitted light or the like is provided. The light emitting circuit is configured by connecting a switching element and a load resistor to the light emitting element, and the switching element is a bipolar transistor. In this case, the base voltage is controlled based on the control from the CPU, and when the switching element is a field effect transistor, the gate voltage is controlled by the CPU.
A photoelectric smoke detector characterized in that the light emission current can be adjusted by controlling based on the control from (1). 2. An electric signal obtained by detecting smoke density as a physical quantity.
(Analog signal) a physical quantity detector, an A / D converter for converting an analog signal output from the physical quantity detector into a digital signal, and a CPU for controlling the entire sensor
And a non-volatile memory, and at least a communication unit that performs transmission via the transmission line between a predetermined device connected to the transmission line, and the physical quantity detection unit includes a light emitting circuit and a light emitting circuit. A light receiving circuit for receiving scattered light due to smoke of emitted light or the like is provided, and the light emitting circuit is configured by connecting a switching element and a load resistor to the light emitting element. Load resistance value of CPU
A photoelectric smoke detector characterized in that the light emission current can be adjusted by controlling based on the control from (1). 3. A sensitivity adjusting method for adjusting the sensitivity of a photoelectric smoke sensor according to claim 1 or 2, wherein the sensor is manufactured by a predetermined device outside the sensor when the sensor is manufactured. With the light emission current of the sensor as a parameter, the output characteristic of the detector with respect to smoke density is measured, and the light emission current that gives the maximum output value within a range that does not saturate at the maximum used smoke density is determined. A sensitivity adjustment method comprising: 4. The sensitivity adjusting method according to claim 3, wherein
The light emission current determined by an external predetermined device is stored in a non-volatile memory of the sensor, and the light emission current stored in the non-volatile memory is hereinafter referred to by the CPU and used for controlling the light emission current. A sensitivity adjustment method characterized in that: 5. A temperature compensation method for compensating temperature characteristics of sensitivity of a photoelectric smoke sensor according to claim 1 or 2, wherein a bipolar transistor is used as the switching element. At the time of manufacture of the device, the emitter voltage value at each of the plurality of base voltage values is measured by an external predetermined device, and a base voltage value corresponding to the emitter voltage for reducing the temperature characteristic is determined from the measured emitter voltage value. A temperature compensation method comprising: compensating a temperature characteristic of a sensor sensitivity by operating a switching element with a voltage value. 6. The temperature compensation method according to claim 5, wherein
The base voltage value determined by an external predetermined device is
Stored in the non-volatile memory of the sensor,
A temperature compensation method wherein a PU compensates for temperature characteristics of sensor sensitivity by applying a base voltage stored in a non-volatile memory to a base of a bipolar transistor.