Abstract:
A charging circuit includes a negative temperature coefficient resistor element serving to verify the temperature of a rechargeable battery cell, such that once the cell is charged to saturation and the temperature of the cell rises to a predetermined level, the negative temperature resistor element will reduce its resistance in response, and in turn cause the charging circuit to automatically switch to a small current charging status, the charging status being maintained once the resistance of the negative temperature coefficient resistor element again starts to increase should the temperature of the cell that is being charged decrease, or should voltage fluctuation remain within a predetermined power supply voltage level, the charging circuit being arranged to reset itself once the rechargeable cell is removed or the power supply suspended.

Description:
BACKGROUND OF THE INVENTION 
     (a) Field of the Invention 
     A Charging Circuit suitable for Broad Voltage Changing Range and of the type of temperature detection automatic cutoff and of Transient Status Maintaining, composed of Transient Maintaining Ckt. suitable for Broad Voltage Range and Negative Temperature Coefficient Resistor Elements serving to verify the temperature of rechargeable cells, such that once the cell is charged to saturation and the temperature of the rechargeable cell rises to a predetermined level, the Negative Temperature Resistor Element will reduce its resistance in response, and that in turn will cutoff the Ckt. automatically, switch to a small current charging status, and the charging status will be maintained once the resistance of the Negative Temp. Coefficient Resistor Element reverts to increase should the temp. of the cell that is being charged go down, or should voltage fluctuation remain within a predetermined power supply voltage level, and the Circuit will reset itself once the rechargeable cell is removed or the power supply suspended. 
     (b) Description of the Prior Art 
     As is well known in the profession, conventionally a Charging Ckt. of the Automatic Cutoff and Transient Status Maintaining Type relies on Voltage or Current Detector composed of electronic elements to charge Rechargeable Cells incorporating Temp. Control Switches which, on sensing that there is a rising in temp. as a result of the rechargeable cell reaching saturation, will cause the charging unit to turn to feed a smaller current to the rechargeable cell, whereby the charging function is maintained all the while, a major shortcoming with such conventional Charging Ckt. of the Automatic Cutoff and Transient Status Maintaining Type is that it involves lots of electronic components built on a complicated structure necessitating expensive costs, and most regrettably, low reliability. 
     SUMMARY OF THE INVENTION 
     The primary object of the invention is to provide a Charging Ckt. suitable for Broad Voltage Changing Range and of the type of Temperature Detection Automatic Cutoff and of the Type of Transient status Maintaining which is able to control a thyrister to cut off the Main Charging Current once the saturation temperature of the rechargeable cell rises to a predetermined level that is sensed on a negative temp. coefficient resistor element which is coupled directly or indirectly to the same rechargeable cell, structurally the invention comprises: 
     Charging power supply: which can be any of a pure D.C., half-wave D.C., Full-Wave D.C., Intermittent Pulsating D.C., or rippled D.C. type; or alternatively one of a stabilized source or one variable source of which voltage variation is restricted within a predetermined ranging; 
     Rechargeable Cell: A Secondary Rechargeable Cell to be matched to a Thermo-control Switch and characterized by a rise in temperature concurrent with saturation; 
     Transient status Maintaining Ckt. fit for a Broad Voltage Ranging; composed of solid state electronic or electric components to be controlled as a function of negative temperature coefficient resistive elements incorporated on the rechargeable cell itself and serving to detect the instantaneous temp. of the same rechargeable cell, such that once at any given instant the charging action taking place on the rechargeable cell brings the temp. up to the point of approaching the saturation temp. the resistance on the part of the negative temp. coefficient resistor will reduce in response, and that eventually putting the Control Thyrister SCR open, meantime a Topping Charge of a smaller magnitude will pass a shunt bypass in parallel across the Anode A and Cathode K of said Thyrister, whereby a continued charging function is maintained concurrent with a continuous charging capability suitable for operation with a Transient Status Maintaining Ckt. under a Broad Voltage Changing Range clear and free of interferences until and unless the power supply is cutoff, or the rechargeable cell removed, whereupon the Transient Status Maintaining Ckt. will reset itself forthwith. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic diagram of an Automatic Cutoff Charging Circuit embodied with a Rechargeable Cell and the Negative Temperature Coefficient Resistive Element integral therewith, prosecuted according to the invention; 
     FIG. 2 is an illustration showing the addition of a Reflow Diode to the circuit shown in FIG. 1 to consummate the Automatic Emergency Power Supply Function. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, an illustration of the invention embodied to be an Automatic Cutoff Charging Circuit integral with a Rechargeable Cell and the Negative Temperature Coefficient Resistive Element, suitable for broad range voltage variation and capable of maintaining a Transient Status, whereof the power supply can be one of a Pure D.C., half-wave D.C., Full-wave D.C., Intermittent Pulsating D.C., or still a rippled D.C. source; or alternatively one of a stabilized source or still one variable source of which voltage variation is restricted within a predetermined ranging; whereas said Automatic Cutoff and Transient Status Maintaining Type Charging Circuit permissive of Temperature Detection within a Broad Range of Voltage Variation is composed entirely or selectively of all or part of parts and components listed below: 
     A.C. Transformer T 100 : whereby A.C. power is delivered to the primary side, and the same is to be output from the secondary side, the A.C. Transformer may be employed selectively per circuitry requirements or it may be dispensed with by having A.C. Current input direct instead; 
     A.C. Limiting Impedance Z 100 : constituted of impedance element which is either capacitive or inductive or resistive, serving to prevent the load side from being shorted. Or alternatively composed of two or more of afore-mentioned impedance elements, as a composite A.C. Limiting Impedance Component, for serial connection way between the A.C. Power Supply and Rectifier BR 100 , theA.C. Limiting Impedance Z 100  being an optional installation; 
     D.C. Limiting Impedance Z 100 ′: an optional Unit, which, in the form of a resistor or active crystal in combination with a drive ckt. may be connected in series way between the D.C. source and the Load side where the power supply is a D.C. system or the working current is of a D.C. form rectified from an A.C. source, so that an A.C. Limiting Impedance Z 100  is not connected serially on the A.C. side, in respect of which installation is dictated by the need; 
     Zener Effect Element VZ 1000 : being an optional element comprising a Zener Diode or a forward bias to be provided by a diode assembly serving a voltage stabilization purpose; 
     Rechargeable Cell B 101 : comprising such rechargeable cells characterized by a rise in temperature once reaching saturation, and in forward series with Blocking Diode CR 102  and Thyrister SCR 101 ; 
     Display and Protection Ckt.: way between the Rechargeable Cell B 101  and the Blocking Diode CR 102 , and way between the Thyrister SCR 101  Series Ckt. and the power supply on which a charging operation relies there may be optionally provided in parallel a Limiting Resistor R 101  with a Light Emitting 
     Diode LED 101 , to account for a Display, this in forward series with Anode A and Cathode K of Thyrister SCR and Rechargeable Cell B 101 , led to the Power Supply; said Limiting Resistor R 101 , Light Emitting Diode LED 101  and Overload Protector F 101  being replaceable with a Filament Bulb L 101 , this Display and Protection Ckt. being and optional device in respect of which installation is dictated by the need; 
     Voltage splitting Resistor R 102 , in series with Trigger Capacitor C 101 , with one pin thereof connected to the positive polarity of the power supply; while the other pin of the Trigger Capacitor C 101  is in series with the crystal side of Photo-coupler PC 101 , thence in conduction with the Trigger Grid G of Thyrister SCR 101 ; the positive polarity of the Thyrister SCR 101  passing to the positive polarity of power supply; where needed or justified, a splitting Resistor R 100  maybe installed in parallel with the junction point where the output terminal of Photo-Coupler PC 101  meets the Trigger Capacitor C 101 , on one point, and with Cathode K, on the other point, to regulate the Thyrister Performance Stability as well as the Trigger Sensitivity; 
     Photo-coupler PC 101 : whereof the input side consists of a photo-emitting diode against which a complementary photo-sensitive crystal constitutes the output side, the input side being controlled as a function of the negative temperature coefficient resistor that is coupled to the rechargeable cell, the output side being in series with the Gate of the Thyrister SCR 101 ; 
     Negative Temp. Coefficient Resistor Element NTC 101 : composed of negative temp. coefficient resistor, may be coupled directly or indirectly with Charging Battery B 101  to have its resistance decreased in response to a rise in the temp. of the charging battery; 
     As means of display LED 102  and a zener diode ZD 101  in series with LED 102  forms voltage limiting and current splitting capabilities, in parallel across the junction points of voltage dividing resistor R 102  and Capacitor C 101  and the negative polarity of power supply to produce voltage limiting and bypass current splitting capabilities, so that the capacitor across both ends is protected intact from interferences due to any fluctuation in power supply voltage while current flowing through ZD 101 , (or further through a selectively provided LED  102  in series with ZD 101 ) serves the purpose of supplementary charge (Topping Charge) with respect to the Rechargeable Battery B 101  following the closure of Thyrister SCR  101 , this Display &amp; Protection Ckt. is an optional provision; 
     Bypass current splitting resistor R 103 : serving as a discharging resistor for Capacitor C 101  on shutdown or when the rechargeable Battery is removed, and which may be provided in parallel way between the Anode A and the Cathode K of the Thyrister SCR 101  optionally where the topping current as required is larger, so as to assist in maintaining a relatively larger charging current, this Bypass current splitting resistor R 103  is an optional provision; 
     Discharging Diode CR 101 : in parallel across the Cathode K and the Gate G of the Thyrister SCR 101 , whose polarity layout is such that on removal of the Rechargeable Battery B 101  it makes possible the formation of a discharging Ckt. together with capacitor C 101  and the Bypass Splitting Resistor R 103 ; 
     Voltage Stabilization Power Supply: composed of a Blocking Diode CR 102  in forward connection with the output end of the charging power supply, then in parallel with the other terminal of the power supply just in order for serial connection with Active Resistor R 110  and the Zener Diode ZD 110 ; both ends of the Zener Diode VZ 110  being output terminals for voltage stabilized power supply; or alternatively composed of other solid state or electromechanical voltage stabilization Ckt., in respect of which the bypass splitting resistor R 103  is an optional provision; 
     Voltage Division Ckt.: composed of the Current Limiting Resistor R 112  in series with the output of the Photo-coupler PC 101 , then in parallel with the Negative Temp. Coefficient Resistor, then altogether in series with Voltage Divider Resistor R 111 , for parallel with the Voltage Stabilization Power Supply, in respect of which the bypass splitting resistor R 103  is an optional provision. 
     What follows is a description of the operation principle of the circuitry illustrated in FIG.  1 : 
     To start charging of a rechargeable battery, instantaneous charging current way from R 102  to Capacitor C 101  triggers the Gate G of Thyrister SCR 101  to conduction so that the circuit begins charging Battery B 101  with normal charging current, when Battery B 101  approaches saturation to bring about a rise in temp., the resistance of the negative temp. coefficient resistor directly of indirectly coupled thereto will decrease, and that in turn brings about a decrease of the voltage across the two terminals of said resistor, such that, by and by the LED on the input side of the Photocoupler PC 101  turns off, the output side cutoff, the thyrister SCR 101  suspended from conduction, whereby voltage occasioned by the charging current passing the bypass resistor R 103  and R 102  is the same as voltage occasioned by current passing LED 102  having a current splitting effect and passing the Zener Diode ZD 110 , as well as an optionally provided Photo-emitting Diode LED 102  mathematically, unaffected by any fluctuation in the power supply voltage; 
     When the negative temp. coefficient resistor undergoes a decrease in temp. so that its resistance reverts to increase, whether this occurs during a Topping Charge or Resetting, potential by the capacitor C 101  will remain unchanged so long as the power supply voltage anytime active falls within a set ranging, as that is a situation whereby no current passes the Thyrister SCR 101  to trigger the Gate G, so the Thyrister SCR 101  will continue to maintain an open state; 
     When the charging is terminated, Battery B 101  is removed, or when the A.C. power input is cut off, potential theretofore stored in the capacitor C 101  will be triggered to discharge by way of bypass current splitting resistor R 103  and the Discharge Diode CR 101 , so that the circuit is reset, to a ready-to-be-triggered state; 
     Moreover, in the foregoing embodiment it is further feasible to install a Reflow Diode FD 201 , serving to allow supply of power way from the Charging Battery to the load driven by the positive/negative output terminals of the principal D.C. Power Source in case of power failure; 
     In FIG. 2 is shown an example of circuitry featuring Emergency Automatic Power Supply by the incorporation of a Reflow Diode FD 201  into the circuit that is shown in FIG. 1, said example comprises essentially: 
     Reflow Diode FD 201 : being reversely paralleled way between the Rechargeable Battery B 101 , positive polarity, and the D.C. Power Supply, positive polarity too; 
     Load: being paralleled way between the negative polarity of the Rechargeable Battery B 101  and the positive polarity of the Power Supply, normally driven by potential from power supply, forms instead a power supply loop together with Reflow Diode FD 201  when power supply is suspended. 
     Stabilization Capacitor C 101 : in parallel with the load to stabilize switching process, in respect of which the capacitance may be determined optionally or omitted altogether. 
     In the embodiments described in reference to both FIG.  1  and FIG. 2, following applications are open to option without effecting any change in circuitry rationale: 
     (1) Arrangement of polarity and serial rapports for components in the Ckt. where needed in coordination with the polarity rapports respecting power supply and circuitry; 
     (2) Having the positive polarity of Rechargeable Battery B 101  connected with the positive polarity of power supply as needed, and the negative polarity K of Thyrister SCR 101  associated with the negative polarity of the cathode K; or alternatively having the positive polarity A of the thyrister SCR 101  connected with the positive polarity of power supply, but the negative polarity of the Rechargeable Battery B 101  with the negative polarity of power supply; 
     (3) Having elements of charging Ckts. (negative temp. coefficient resistors) produced and assembled to the charging device where justified by a need, or alternatively having elements of charging Ckts. and rechargeable cells produced and assembled together, or still having part of Ckt. elements installed in the charging unit, others installed in the Rechargeable Cell, to be interconnected mutually by conductor means or contacts, plug/socket sets. 
     In summation, in this invention, a charging circuit suitable for broad voltage changing range and of the type of temperature detection automatic cutoff and of the type of transient status maintaining, by detecting battery charging saturation and a temperature rising condition by means of negative temperature coefficient resistor elements installed in the charging battery, it will switch to an automatic Topping Charge status in the event the battery has reached saturation as a result of charging, meantime restrict interference on the capacitor due to any fluctuation in power supply voltage, while current flowing past voltage divider resistor R 102  and current flowing past Zener Diode ZD 101  as well as an optionally provided photo-emitting diode LED 102 , in series connection, serve as Topping Charge for the Rechargeable Cell, a further advantage lies in the provision of a reflow diode to make for an emergency automatic power supply Ckt. Overall, the structure is simple but highly effectual.