Abstract:
The present invention relates to a blower dryer appliance typically used for drying and styling hair. When electrically activated, these appliances virtually always route electrical power to the fan or blower motor prior to or simultaneously with the heating element(s). Semiconducting switching devices used for regulating, controlling and/or switching electrical power generate waste heat that must be dissipated. Typically, heat is conducted and/or channeled away from the semiconducting switching device through a heat sink which is thermodynamic-mechanically coupled to the device. The greater the coverage area of the heat sink, the more waste heat can be dissipated depending on the ability of the heat sink to make contact with cooler, ambient air. This adds costs to the dryer/blower for engineering the heat sink, cost of the sink itself, and necessary design changes in the dryer/blower for accommodating the sink. The presently disclosed invention utilizes the inherent characteristics of the dryer/blower for channeling and reusing waste heat generated from an active switching device by positioning the active device in the air path of the blower. Relocating the heat generation portion of the control circuitry to the air path has three major benefits: greater cooling effect for the switching transistor and therefore more efficient transistor conduction and switching operation; utilizing smaller and less costly heat sinks; and the cumulative effect of combining the waste heat generated by the switch to the intentional heat effect generated by heating element(s).

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     The present application is a continuation in part of and claims priority from the following co-pending U.S. patent applications: 
     U.S. patent application entitled “Portable Hair Dryer” having application Ser. No. 10/117,776 filed on Apr. 4, 2002, currently pending, which is a divisional of Ser. No. 09/662,860, now U.S. Pat. No. 6,449,870 entitled “Portable Hair Dryer” and filed on Sep. 15, 2000. The above-identified applications are incorporated by reference herein in their entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is generally related to a combination dryer and blower appliance. More specifically, the present invention is related to control circuitry for controlling the electrical components of a dryer/blower. 
     2. Description of Related Art 
     There are many different types of hair dryers/blowers. For instance, typical hair dryers are shown in U.S. Pat. Nos. 4,195,217; 5,555,637; and 5,701,681. All of them, however, have AC cords attached and are not portable and self-contained. U.S. Pat. No. 6,449,870 entitled “Portable Hair Dryer” and by the inventor of the present invention discloses a portable dryer/blower appliance which uses an optional battery for its power supply. 
     Typically, prior art appliances of the type identified above have made use of a mechanical contact switch or switches for controlling the electrical power to the heating element(s) and blower motor. In general, these switches are fairly efficient as they do not generate any appreciable waste heat while conducting electricity. Any minimal waste heat that is generated by the switch while it is conducting is of such low intensity that it can easily be dissipated through the body of the dryer/blower without the need for extensively modifying the appliance, or even considering the switch heat in the initial design stages. 
     As mentioned, switches in prior art appliances typically consist of only the mechanical contact type due to several factors, the preeminent factor being the manufacturing costs associated with direct current (DC) operation. However, dryer/blower appliances have been recently introduced which use active devices for their switching capabilities, such as CMOS transistors and the like. Typically, this requires that the electrical power be converted from alternating current (AC) to DC, or alternatively, to elaborate mirror circuits for controlling the respective positive and negative portions of the AC power cycle. 
     Power transistors, unlike mechanical contact switches, can generate substantially more waste heat that must be dissipated (depending on the characteristics of the particular transistor type). Failure to properly channel the waste heat away from the device will often degrade its performance, making it less conductive, resulting in more waste heat which is not channeled away from the device, more inefficiency, and eventually causing the device to fail due to overheating (this is referred to as the “heat avalanche effect”). Additionally, certain semiconductor switching devices generate proportionally more heat as a result of changing states from insulator to conductor than from conducting electricity alone. Therefore, again depending on the characteristics of the individual transistor type selected for use, pulsing circuits using these devices potentially generate even more waste heat than devices employed for merely switching the electrical power to the electrical components of the dryer/blower “on” and “off.” 
     SUMMARY OF THE INVENTION 
     The present invention relates to a blower dryer appliance typically used for drying and styling hair. When electrically activated, these appliances virtually always route electrical power to the fan or blower motor prior to or simultaneously with the heating element(s). Semiconducting switching devices are used for regulating, controlling and/or switching electrical power generated from waste heat that must be dissipated. Typically, heat is conducted and/or channeled away from the semiconducting switching device through a heat sink which is thermodynamically and mechanically coupled to the device. The greater the coverage area of the heat sink, the more waste heat can be dissipated depending on the ability of the heat sink to make contact with cooler, ambient air. This adds costs to the dryer/blower for engineering the heat sink, cost of the sink itself, and necessary design changes dryer/blower for accommodating the sink. The presently disclosed invention utilizes the inherent characteristics of the dryer/blower for channeling and reusing waste heat generated from an active switching device by positioning the active device in the air path of the blower. Relocating the heat generation portion of the control circuitry to the air path has three major benefits: greater cooling effect for the switching transistor and therefore more efficient transistor conduction and switching operation; utilizing smaller and less costly heat sinks; and the cumulative effect of combining the waste heat generated by the switch to the intentional heat effect generated by the heating element(s). 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the present invention are set forth in the appended claims. However, the invention itself, as well as a preferred mode of use, further objectives and advantages thereof, will be best understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings wherein: 
     FIG. 1 is a perspective view of the novel hair dryer/blower in accordance with an exemplary embodiment of the present invention; 
     FIG. 2 is a schematic representation of a converter for supplying either AC or DC power to the battery for charging thereof and is a perspective view of the novel battery that can be attached to the dryer/blower as shown in FIG. 1 in accordance with an exemplary embodiment of the present invention; 
     FIG. 3A is a block diagram of the control circuit for controlling the power to the blower fan and to the heating element in accordance with an exemplary embodiment of the present invention; 
     FIG. 3B is a circuit illustrating a one-circuit embodiment for quickly heating the heating element and then supplying pulsed current or voltage to maintain the heat while dissipating waste heat into the air path in accordance with an exemplary embodiment of the present invention; and 
     FIG. 3C illustrates the details of the pulsing circuit illustrated in FIG. 3B with the active device of the circuit located remotely from the circuit for dissipating waste heat into the air path in accordance with an exemplary embodiment of the present invention. 
    
    
     Other features of the present invention will be apparent from the accompanying drawings and from the following detailed description. 
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 is a perspective view of novel dryer and dryer appliance  10  useful for drying hair and the like, including elongated hollow body portion  12 , handle portion  14  and battery base portion  16 . It will be noted that mass center line  18  of each of elongated hollow body portion  12 , handle  14 , and battery base  16  are all in alignment, thus allowing unit  10  to be balanced and enabling the hair dryer/blower to stand alone on base  16 . In addition, by the alignment of the mass center lines of elongated hollow body portion  12 , handle  14  and base  16 , and proper weight distribution of hollow body portion  12  and base  16 , as can be done by those skilled in the art, balance is provided to enable the unit to be used with minimum strain on the arm and hand of the user. 
     Elongated hollow body portion  12  has one or more heating element(s)  20 , blower motor  22  and circuit  24 . Circuitry  24  may be of one or more types of circuitry including pulsing circuitry as disclosed in U.S. Pat. No. 6,449,870 entitled “Portable Hair Dryer” and incorporated by reference herein in its entirety. Circuitry  24  will also be described in somewhat more detail hereafter. Elongated hollow body portion  12  also has posterior end  26  and anterior or front end  28 . Notice that air flow path  25  results from blower motor  22  being switched “on” which includes cool air  21  being drawn in at posterior end  26  and warm air  23  being exhausted at front end  28 . Notice also that circuit component  66 A and  66 B are positioned in cool air  21  portion of air flow path  25 , either before blower  22 , i.e., circuit component  66 A, or subsequent to blower  22 , i.e., circuit component  66 B, in air path  25 . Circuit component  66 A and  66 B is further electrically coupled to circuit  24  as will be described below. 
     Handle  14  also has switch control pedestal  30  and mechanism  32 , well known in the art, for locking battery/base unit  16  to handle  14 . Switch pedestal  30  includes diode light  34 , usually green in color, but may be of any desired color. Switch  36  (S1) controls power only to the blower motor and switch  38  (S2) controls power to both the blower motor and the heating element. Manual control switch  40 , which will be explained in detail hereafter, has multiple positions such as low, medium and high that can be selected by the user to designate the heat desired to be produced by heating element  20 . The weight of base  16  is in balance with the weight of elongated body portion  12 . Such balance can be easily achieved by those skilled in the art. 
     Note in FIG. 2 that plug-in unit  54  could generate either AC or DC power output voltage on jacks  56  and  58 . If the battery unit has its own rectifier unit, then jacks  56  and  58  in FIG. 2 may generate AC voltage. If a type of battery unit is selected that does not have a rectifier, then plug-in unit  54  may be an AC to DC converter and jacks  56  and  58  would generate DC voltage, or alternatively, a rectifier included in dryer and dryer appliance  10 . As mentioned herein, typical prior art dryer/blower switches consist of only the mechanical contact type devices usually capable of switching either AC or DC power. Utilizing AC power was generally considered far more economical because the components of the appliance lent themselves to operation from AC power, usually available from an AC wall outlet. Thus, expensive power rectifying circuits were avoided, and so the manufacturing costs associated with direct current (DC) operation were lowered. However, dryer/blower appliances have been recently introduced which use active devices for their switching capabilities, for one reason or another (for example U.S. Pat. No. 6,449,870 for pulsing power to the heating element), which utilize semiconducting switching devices such as CMOS transistors and the like. Typically, the electrical power typically should be converted from alternating current (AC) to DC, or alternatively, the AC power should be divided into its respective positive and negative portions and each portion controlled by mirrored control circuits. Here it should be understood that exemplary embodiments of the present invention will be described herein with regard to the pulsing circuit disclosed in the U.S. Pat. No. 6,449,870. Those of ordinary skill in the art will readily recognize that the concepts and principles described herein could be applied to types of control circuitry other than pulsing circuits that control and influence electrical power in a variety of dryer/blower appliances. Furthermore, with the teaching of the present invention, the ordinary skilled artisan could easily modify those types of appliances with the presently described invention as taught herein. 
     FIG. 3A discloses the basic electrical circuit for controlling power to the blower fan and to the heating element in accordance with an exemplary embodiment of the present invention. Basic circuit  62  includes the battery portion, if so configured, with the battery cells therein and, if desired, the rectifier unit. Optionally, it may also have a jack for connecting a charger thereto. When the unit is plugged into a power source, the power is immediately supplied to LED  34  which indicates that the battery has sufficient power to operate the unit. When switch button  36  (S1) is depressed, fan motor or blower  22  is operated alone. When switch  38  (S2) is closed, two sets of contacts are closed: one coupling power to fan  22  and the other coupling power to heating element  20  through pulsing circuit  64 , if desired. The pulsing circuit  64  will be described hereafter. Alternatively, electrical power may be routed directly to circuit  64  and switch  36  (S1) and switch  38  (S2) is coupled to a micro current for controlling “switching voltages” circuit  64  (not shown). In accordance with that exemplary embodiment of the present invention, circuit  64  would control the power to heater  20  and fan  22  rather than to mechanical switches  36  (S1) and  38  (S2). 
     With regard to the pulsing circuit embodiment, circuit  64  is shown in detail in FIG.  3 B. When the unit is first turned on and switch  38  (S2) is depressed, both the heating element and the blower motor are energized and it is desired that the heating element heat as quickly as possible. Thus, as shown in FIG. 3B, when switch  38  is closed, conductor  39  is coupled directly to the input of transistor  66 . The temperature of heating element  20  is monitored by a temperature sensor, such as a thermocouple or thermistor. Temperature sensor  68  is coupled to comparator  70 . Another voltage reference  72  is coupled to the other input of the comparator representing the proper or maximum heating temperature of element  20 . Since there is no heat at first, there is no output from comparator  70 . That lack of signal is detected by inverting diode  73  which generates an output signal on line  76  that is coupled to base  78  of power transistor  66  causing it to conduct. Thus, full voltage is applied to heating element  20  to provide maximum heating in minimum time. As soon as the element is heated to the desired temperature, and that is sensed by sensor  68 , an output signal is generated by comparator  70  that causes inverting diode  73  to remove its signal on output line  76 , thus removing the continuous signal from base  78  of transistor  66 . At this time, pulsing circuit  80 , which is isolated from inverting diode  73  by isolating diode  82 , provides pulses to the base  78  of transistor  66  to maintain the heat attained by heating element  20  without having a continuous voltage applied thereto. 
     However, rather than supporting transistor  66  locally on circuit  64 , the transistor is located remote from the circuit. It is expected that transistor  66  will generate a substantial amount of waste heat during its operation. This heat, if not channeled away from circuit  64 , will degrade the performances of both transistor  66  and other heat sensitive components on located on circuit  64 . Therefore, transistor  66  is relocated from circuit  64  proximate to air path  25 . In so doing, cool air drawn into air path  25  by blower  22  surrounds transistor  66  and takes on waste heat dissipated from transistor  66  and continues on as warm air  23 . Thus, the operational life and efficiency of transistor  66  are increased, and the waste heat is added to air path  25  for use in drying, thereby lowering the heating burden on heat element  20 . Optionally, heat sink  67  may be thermodynamically and mechanically coupled to transistor  66  which is consistent with a manner known to those of ordinary skill in the relevant art. 
     Returning to FIG. 1, notice that the transistor/optional heat sink component is depicted in one of two possible positions in air path  25 , either before (component  66 A), or after (component  66 B) blower  22 , but always being positioned in the air stream before heat element  20 . In either of these locations, the heat generated by component  66 A/ 66 B is not merely exhausted into the ambient air, but is recycled as useful heat for supplementing the heat generated by heat element  20 . The best location for the transistor/optional heat sink component will most likely be a function of the particular dryer/blower design, but vibration, electrical interference and cooling capacity should all be considered in selecting the precise location for the transistor/optional heat sink component. It is also expected that in certain situations, such as in an AC controlled embodiment, multiple transistor/optional heat sink components equivalent to one or both of component  66 A/ 66 B will be present, such as in AC operational control. 
     Pulsing circuit  64  is shown in detail in FIG.  4 B. When the unit is first turned on and switch  36  (S 1 ) is depressed, the heating element is energized and it is desired that the heating element heat as quickly as possible. Thus, as shown in FIG. 4B, when switch  38  is closed, conductor  39  is coupled directly to the input of transistor  66 . The temperature of heating element  20  is monitored by a temperature sensor, such as a thermocouple or thermistor. Temperature sensor  68  is coupled to comparator  70 . Another voltage reference  72  is coupled to the other input of the comparator representing the proper or maximum heating temperature of element  20 . Since there is no heat at first, there is no output from comparator  70 . That lack of signal is detected by inverting diode  73  which generates an output signal on line  76  that is coupled to base  78  of power transistor  66  causing it to conduct. Transistor  66  is turned on by the signal on output line  76 . Thus, full voltage is applied to heating element  20  to provide maximum heating in minimum time. As soon as the element is heated to the desired temperature and is sensed by sensor  68 , an output signal is generated by comparator  70  that causes inverting diode  73  to remove its signal on output line  76 , thus removing the continuous signal from the base  78  of transistor  66 . At this time, pulser circuit  80 , which is isolated from inverting diode  73  by isolating diode  82 , provides pulses to base  78  of transistor  66  to maintain the heat attained by heating element  20  without having a continuous voltage applied thereto. 
     Pulser circuit  80  is shown in detail in FIG. 3C in accordance with one exemplary embodiment of the present invention. Oscillator  84  applies pulses to circuit  86  that could be a shift register, a timer, a counter, or a divider circuit as shown in U.S. Pat. No. 4,571,588, which is incorporated herein by reference in its entirety. The duty cycle is the percentage of time a unit is used or the ratio of operation time to shutdown time. If a device capable of only fixed length pulses is used for controlling the duty cycle, then the ratio can be adjusted only by designating more or less pulses as operation pulses. If, however, the period of the pulses can also be altered, then the duty cycle can be altered by either increasing the ratio of the operation pulses to shutdown pulses, or by lengthening the duration of the operation pulses in the cycle. Thus, selecting a device having output pulse width modulation capability allows for adjusting the duration of the operation period as well as the ratio of operation periods. Many types of times and shift registers known in the art have pulse width modulation capabilities. In accordance with one exemplary embodiment, circuit  86  may be a 4-bit shift register as depicted in FIG.  3 C. Input switch  40  is used for selecting select low, medium and high heat causing a selected bit from one stage of circuit  86  to be connected to base  78  of transistor  66  thus causing transistor  66  to be pulsed on and off at a given rate. An example is illustrated in FIG. 5D of the U.S. Pat. No. 4,571,588 and is not reproduced herein. 
     While the present invention has been described with reference to an exemplary DC-powered dryer/blower appliance which utilizes pulsing circuitry for minimizing power consumption, one of ordinary skill level in the relevant art would readily understand that the principles and concepts discussed herein are equally relevant for other types of appliances. One such appliance is an AC-powered dryer/blower appliance, as alluded to above, in which circuit component  66 A, and/or, circuit component  66 B may be comprised, at least partially, of heat generating solid state devices, e.g. thyristors, sometimes referred to as silicon controlled rectifiers (SRCs), more modern gate turn off (GTO) thyristors and triacs, a complementary thyristor structure suitable to control AC power, which are all well known and their uses are well understood by those of ordinary skill in the relevant art. In accordance with an exemplary embodiment of the present invention, circuit  24  provides gate control, for turning “on” and “off” the heat generating devices of circuit component  66 A, and/or, circuit component  66 B, e.g. for sending a positive pulse current to a GTO thyristor for “on” condition and a negative pulse current to GTO thyristor gate circuit for “off” condition. The techniques described herein with regard to the present invention may be incorporated in the AC active switching device of such an AC powered appliance. Additionally, and as alluded to above, the techniques described herein with regard to the present invention may be incorporated in the DC active switching device for a DC powered appliance, such as a battery operated portable dryer/blower appliance. 
     The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.