fig1 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 fig2 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 fig2 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 . fig3 a 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 fig3 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 fig3 b , 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 fig1 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 fig4 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 fig4 b , 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 fig3 c 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 fig3 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 fig5 d 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 .
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 . 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 .