GB2220478A - An improved automatic electric lamp - Google Patents

Abstract

An automatic electric lamp has a switch (SW) in its circuit, whereby the lamp may be operated as an automatic lamp with adjustable brightness, or may be operated as an ordinary lamp also with adjustable brightness. In view of the conventional automatic electric lamp having a drawback of blinking upon being turned on, the circuit of this automatic electric lamp has a blinking-proof circuit, whereby the lamp does not blink upon being turned on. The lamp has an infra-red sensor for sensing human body radiation, and an ambient light sensor (CdS). When the infra-red sensor is triggered, the blinking-proof circuit grounds one end of a resistor (R23) to reduce the sensitivity of the ambient light sensor. The lamp brightness is adjusted using a variable resistor (VR4) which changes the conducting angle of a silicon bilateral switch (ST1). <IMAGE>

Description

"AN IMPROVED AUTOMATIC ELECTRIC LAMP" The present invention provides an improved automatic electric lamp, which is particularly aimed to improve the circuit of the conventional automatic electric lamp so as to make the lamp more practical in use.

In the conventional automatic electric lamps, an infrared sensor is generally used to detect a person approaching the sensing range, and a Cds is also used for detecting the brightness of ambient light so as to form an automatically triggered illuminating device to prevent the user from groping a switch in the dark, and forgetting to turn off the lamp switch; however, the conventional automatic electric lamp still has some drawbacks as follows: (1). The infrared sensor has a limited detecting range, and the place of using that infrared sensor is also limited considerably.It may conveniently be installed in a portal or a bothroom that has a small space, where person usually stays a very short time, but it is not practical to install such a sensor in a living room, or bedroom, where some persons may often walk around; for instance, a person may walk from the living room to kitch or bedroom. The time for a person staying in those places might be rather short, but it is un-necessary to turn off the light therein in terms of practical requirement; in other words, when an automatic electric lamp is installed in such place,the lamp would be truned off automatically upon a person walking away from the effective range of the sensor, and it would cause inconvenience to the user.

When there are some persons to stay in the living room watching television program or talking, it is deemed un-necessary to use an automatic lamp only for wasting purpose.

(2). When a conventional automatic electric lamp is turned on, the Cds therein is usually affected by the variation of brightness to have an intermittent blinking phenomenon. In order to overcome that blinking phenomenon, the Cds should be installed in such a manner that it must be at a position not whithin the bulb illuminating range; in that case, the installing position of the Cds will be limited, i.e., the best position for sensing the light would be impossible, and then the sensitivity of the Cds would be affected. Moreover, after the conventional automatic lamp being turned on, the sensor still has input signal, upon the counting time being expired, because of the delay circuit; as a result, the lamp would have a blink, which would cause more or less inconveniences to the user.

(3). When a conventional automatic lamp is turned on, it will reach its full brightness immediately without having any adjustment. As our living standards have been elevated with each passing day, everything is required to provide a complete and best quality, and therefore the drawback of the conventional automatic lamp as mentioned above must be improved.

In view of the aforesaid problem, the inventor has set a prime object for the present invention, i.e., to improve the circuit of the conventional automatic lamp by adding a switching circuit therein, whereby the lamp can provide two operational modes, i.e., (1) it may be set as an automatic lamp with gradual adjustment in brightness, (2) it may be set as an ordinary lamp still with gradual adjustment in grightness.

Another object of the present invention is to provide a blinking-proof circuit to overcome the blink phenomenon of the conventional automatic lamp upon being turned on; the position of the cds may be changed, if necessary, so as to obtain the best sensing result.

A further object of the present invention is to provide a circuit, which can use a power supply of llOV or 220V merely by changing the value of resestor R22, and it is deemed a practical feature.

A still further object of the present invention is to provide a silicon bilateral switch STl that has contact point; that switch has a considerable serviceable life without trouble, and therefore it is deemed a practical design.

An embodiment of the present invention will be described below in detail by way of example with reference to the accompanying drawing, in which: FIG. 1 illustrates a sensing and control circuit according to the present invention.

Referring to FIG.1, there is shown a complete circuit according to the present invention, of which both the well-known and newly designed portions are described in detail as follows: Well-known portion: A thermoelectric type of infrared sensor, being used for picking up signal: The sensor has a convergent lens for converging the infrared rays radiated from a person's body; then, the infrared rays picked up are converted into a voltage signal to be coupled to an IC (integrated circuit).

An IC: It is a control circuit for controlling an illuminating device. The positive terminal (+) of 1Cla is connected and driven with the sensor for amplifying the signal via ICla. Capacitor Cl is a filter capacitor.

The ICla, R2, R3, C2, and C3 are connected together to form a non-inverting AC amplifier, whereby the un-necessary frequencies are cut off, and only the required frequency band is to be amplified. The amplified signal is to be coupled, via C4 and R4, to the negative terminal of IClb for further amplification and filtering through an inverting AC amplifier, which comprises IClb, resistors R4, RS, VRl, C4 and C7; the un-necessary frequencies will also be cut off, and only the necessary frequency is to be amplified.

The semi-variable resistor VRl is used for adjusting the amplification factor of ICib. The output signal of ICib further pass through an amplitude limiting-comprartor comprising IClc, ICld, R6, R7, R8 and R9 so as to determine whether the transistor TRl should be triggered and grounded; in other words, when the input signal voltage level is lower than the reference voltage on the negative terminal of IClc, the output of IClc will be in "LOW" state; otherwise, the output of IClc will be in "HIGH" state. The condition of ICld is just contrary to that of IClc.When the unput level of ICld is higher then the level on the negative terminal of IClc, or the level on the positive terminal of ICld, a positive potential will pass through resistors Rl0, Rll, R12 to couple with the base of TRl to have TRI become conducted and grounded; in that case, the potential across R14 will be changed from "HIGH" to "LOW"; the terminal "IN" of IC-2 will be set in "LOW" state. When the reset terminal Cl of IC-2 is in "HIGH" state, the terminal T2 of IC-2 will be in "LOW" state. Since C8 discharges via terminal T2, the output terminal "OUTs' of IC-2 will have a "HIGH" output. The output will pass through Rl8 and R19 to be coupled to the bases of transistors TR2 and TRS respectively; then, TR2 will be grounded, and R21 will also be grounded. In that case, the base of TR3 will lose its positive bias, and therefore TR3 become an open state.

The aforesaid control circuit can automatically stop the operation of the illumination driving circuit when the illuminating soutce being strong enough, i.e., the sensor signal generated by the sensor being unable to drive the illuminating device to light up. The theory is that when the illuminating light is strong enough, the resistance of Cds will be reduced, i.e., its IR drop becoming reduced; then, the base of transistor TR4 would have a bias to cause TR4 to become grounded, and simultaneously one end of resistors RiO and Ril will be grounded to cause the output of IClc and ICld to become interrupted; in that case, transistor TRI would not become conducted because of having no positive bias.Therefore, when the illuminating light is strong enough, the illuminating device will not be turned on even if a person's body enters within the range of the sensor of the present invention.

In addition to the obvious techniques, the novel features of the present invention are described as follows: (1). By means of a switch, the automatic lamp may be remained as an automatic electric lamp "A", or changed into an ordinary electric lamp "D". The design theory thereof is that when the switch is set at position "A", the potential of resistor 21 is controlled with transistor TR2. When TR2 being in not conducting state, a positive voltage will present on the base of TR3 via R20 and R2l to cause TR3 to become conducted and grounded; as a result, capacitor Cil will also be grounded to cause D3 to have no bias, becoming not conducted; as a result, the silicon bilateral switch STl will be cut off to cause the lamp to be turned off.In that cause, the lamp is operated as an automatic lamp. The LED will be sighted up to indicate the operation mode of the lamp. When the switch is set at position "D", the resistor R21 will be grounded, and the lamp will be operated as an ordinary electric lamp without having any automatic feature.

(2). The brightness of the lamp may be adjusted gradually no matter it being operated in an automatic or ordinary mode; the design theory thereof is that when transistor TR3 is in open circuit state, the capacitor Cli is no more in grounded state. Capacitor Cli will be charged with a voltage via VR4 and R25; when the voltage on the capacitor is higher than the trigger voltage of the bilateral diode D3, D3 will become conducting, and the silicon bilateral switch STl will be triggered to cinduct, and the power will flow through STl to light up the lamp. The diodes D4 to D7 form a -bridge type of full-wave rectification circuit so as to have both of the half-cuples of A.C. power across Cii controlled by transistor TR3.

In the event of varying the value of the semi-variable resistor VR4, the conducting time of D3 will also be changed, and the conducting angle of the silicon bilateral switch STl will also be varied.

In that case, the current value passing through STl will be different, and the brightness of the lamp will also be affected. If a regulator is used to adjust the value of VR4, the grightness of lamp can be adjusted gradually R26 and C12 in the circuit are used for preventing the silicon bilateral switch STl from being up-intentional touch, i.e., to insure the stability thereof.

(3). The design of a blinking-proof circuit: By means of that design, lamp being operated in an automatic lamp mode would not blink; otherwise, the lamp would blink because that, when a person enter into the sensing range, the sensor will generate a signal to trigger the circuit to turn on the lamp; simultaneously, when the lamp throws light on the Cds, the resistance value of Cds will be reduced to cause transistor TR4 to become conducted and grounded. The output of IClc and ICld will be cutoff; IC-2 will also have no output; TR2 will not be in conducting state; then, the positive potential will pass through R20 and R21 to reach the base of TR3; TR3 will be in conducting state, and Cli will be in short state to cause the silicon bilateral switch to become non-conductive, and therefore the lamp will be turned off.After the lamp being turned off, the resistance value of Cds will be increased because of having no sufficient light rays in the vicinity thereof; in that case, IClc and ICld will again have output to turn on the lamp; consequently, the aforesaid condition would happen repeatedly to cause the blinking state of lamp. In the conventional automatic lamp, when the lamp is turned on, the tuning circuit thereof will be triggered, and the discharging time will be set by means of a variable resistor. After the discharging time set being expired, and if the sensor still having an input signal (i.e., a person's body still being within the range of the sensor), the lamp will have a blink, which will take palce repeatedly as long as a person staying within the range of the sensor; that phenomenon would cause a user feeling uncomfortable.

In view of the aforesaid drawbacks, the inventor has developed a blinking-proof circuit incorporated in the present invention; when a person's body enters into the range of the sensor, the circuit will be triggered to cause the terminal "OUT" of IC-2 to have a "HIGH1, output, which will pass through resistor RiB to reach the base of transistor TR5 to cause TR5 to be grounded; one end of R23 will be grounded to cause the resistance value of Cds to vary, and transistor TR4 will not be grounded.According to the aforesaid circuit designed, two functions can be obtained, i.e., (1) during the lamp being lighted up, the resistance value of Cds will vary to cause TR4 not to be grounded; the lamp would not be turned off, or would not blink. (2) during the period from the lamp being lighted up to turned off, the delay circuit can only count repeatedly without causing the lamp to blink quickly after each count time expired; therefore, the whole device would have no any defect.

In addition to the aforesaid circuit, the present invention is also furnished with (1) a delay circuit, of which the delay time may be varied upon the value of the semi-variable resistor VR2 being changed so as to maintain the lamp in lighting-up.state for a given period of time in case of a person entering into the sensing range for a very short time; (2) a delayed starting circuit, which is used to prevent the circuit and sensor from initial unstable and mis-sensing operation upon the power supply being turned on; 13) both ends of the power line being connected in parallel with a surge absorber ZNR for absorbing surge waves and other signals to prevent from interference. The resistor R22 is a voltage-dropping resistor; the voltage of power supply after being dropped will pass through diode D2 to become a DC (direct current). Diode Dl is used for stabilizing the voltage across it.

Capacitors C5 and ClO are filtering capacitors to filter the undesirable signals so as to provide a pure DC. IC3 is a voltage-stabilizing IC for maintaining the power supply in a constant stable condition to prevent from any wrongful operation.

Claims (4)

1. l. An improved automatic electric lamp, which being able to operate as an automatic lamp and an ordinary lamp by means of switching in its circuit; and said circuit being connected in series with a blinking-proof circuit to prevent said lamp from blinking upon said lamp being turned on; and when a resistor R21 in said circuit being grounded, said automatic lamp being changed into an ordinary lamp; and said circuit being furnished with a brightness adjusting means for adjusting the brightness of said automatic lamp and said ordinary lamp.
2. 2. A blinking-proof circuit as claimed in claim l, of which the feature is that when a person enters the sensing range of the sensor, the terminal "OUT" of IC-2 in said circuit will have a "HAVE" output to pass through resistor RiB to reach the base of transistor TR5 to cause said TR5 to be grounded, and one end of resistor R23 being also grounded to cause the value of Cds to be varied, and therefore transistor TR4 being in non-conducting state and being not grounded.
3. 3. A brightness-adjusting means as claimed in claim 1, of which the resistance value of a semi-variable resistor VR4 can be adjusted for gradually adjusting the brightness of said lamp; ;and the theory of said brightness adjustment is that when transistor TR3 is in open circuit state, capacitor Cli will not be grounded, and voltage passing through semi-variable resistor VR4 and resistor R25 to charge capacitor Cull; and when the voltage exceeding the conducting voltage of diode D3, D3 will become conductive, and a silicon bilateral switch STl will have a triggering voltage to become conductive, and then the power supply passing through said STl to turn on the lamp; and if the resistance value of said semi-variable resistor VR4 being changed, the conducting time of said diode D3 will be changed to vary the conducting angle of said STI, and then the voltage across said STl will also be different to cause the lamp to have different brightness.
4. 4. An electric lamp substantially as herein described with reference to and as illustrated in the accompanying drawing.