BACKGROUND OF THE INVENTION 0001 1. Field of the Invention 0002 The present invention relates to a power control circuit for use in a vending machine and, more particularly, to such a power control circuit, which drives the bill accepter of the vending machine into the power-saving stand-by mode when the bill accepter receiving no bill. 0003 2. Description of the Related Art 0004 In public places, a variety of automatic vending machines may be installed to provide candy, ticket, changes, etc., when a coin or bill is dropped in. A big vending machine comprises a bill accepter and a number of vending main units. Conventional vending machines are commonly designed to consume city power supply directly. When installed, the bill accepter is constantly maintained turned on. Because the bill accepter is constantly maintained turned on, much electricity is consumed when the vending machine runs idle. 0005 Therefore, it is desirable to provide a power control circuit for use in a vending machine, which eliminates the aforesaid drawbacks.

SUMMARY OF THE INVENTION 0006 The present invention has been accomplished under the circumstances in view. It is therefore the main object of the present invention to provide a power control circuit for use in a vending machine, which automatically turns the bill accepter from the working mode to the stand-by mode when vending machine receiving no bill, or from the stand-by mode to the working mode when the vending machine receiving a bill. According to one embodiment of the present invention, the power control circuit comprises a pulse signal generator installed in the bill inlet of the bill accepter of the vending machine and adapted to generate a triggering signal upon insertion of a bill into the bill inlet of the bill accepter, a driver, and a trigger, which controls the driver to drive the bill accepter between the power-saving stand-by mode and the work mode subject to the presence of the pulse signal from the pulse signal generator. According to an alternate form of the present invention, the power control circuit comprises a trigger adapted to generate a triggering signal, and a driver adapted to receive the triggering signal from the trigger. The driver connects power supply to the bill accepter when receiving the triggering signal from the trigger, or disconnects power supply from the bill accepter when receiving no signal from the trigger.

BRIEF DESCRIPTION OF THE DRAWINGS 0007 FIG. 1 is a circuit block diagram showing the system arrangement under the first trigger mode according to the present invention. 0008 FIG. 2 is a circuit block diagram showing the system arrangement under the second trigger mode according to the present invention. 0009 FIG. 3 is a circuit block diagram of the power control circuit according to the present invention. 0010 FIG. 4 is an operation flow of the present invention when started (I). 0011 FIG. 4A is an operation flow of the present invention when started (II). 0012 FIG. 5 is a stand-by mode operation flow chart according to the present invention. 0013 FIG. 6 is a bill rejection mode operation flow chart according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 0014 Referring to FIGS. 1 and 3, a power control circuit 10 constructed according to the first trigger mode of the present invention is installed in a vending machine and electrically connected between the bill accepter 20 and vending main units 30 of the vending machine, comprising a pulse signal generator 13, a trigger 11, and a driver 12. The pulse signal generator 13 is installed in the inlet of the bill accepter 20. The PIN OUT of the trigger 11 is connected to the vending main units 30. 0015 After a predetermined length of time in which the inlet of the bill accepter 20 received no bill, the bill accepter 20 triggers a D-type flip-flop (U1) 111 to draw PIN6 from high potential to low potential, thereby causing PIN5 to be zeroed. At this time, a N-channel field effect transistor (Q2) 121 of the driver 12 is caused to turn off a P-channel field effect transistor (Q3) 122, stopping main power supply from passing to the bill accepter 20, and therefore the bill accepter 20 directly enters the power-saving stand-by mode and outputs an enable signal EN to a N-channel field effect transistor (Q1) 112 of the trigger 11 to keep PIN OUT in high potential, informing the vending main units 30 of the stand-by mode status of the bill accepter 20. When entered the stand-by mode, an oscillation module 131 of the pulse signal generator 13 drives a LED (light emitting diode) 132 to emit light, which is ten received by a phototransistor 133 to hold Vpt in low potential, waiting for work mode. 0016 When a bill entered the inlet of the bill accepter 20, it blocks the light of the LED 132, thereby causing RC (resistance-capacitance) to be charged to change Vpt from low potential to high potential and to further trigger PIN1 of the D-type flip-flop (U1) 111 and change the status of PIN5 of the D-type flip-flop (U1) 111 from low potential to high potential. When PIN5 of the D-type flip-flop (U1) 111 changed to high potential, the N-channel field effect transistor (Q2) 121 is driven to turn on the P-channel field effect transistor (Q3) 122, enabling main power supply to pass to the bill accepter 20. At this time, the trigger 11 outputs an enable signal to drive the N-channel field effect transistor (Q1) 112, causing PIN OUT to be changed from high potential to low potential. When PIN OUT changed to low potential, the trigger 11 gives a signal to the vending main units 30, informing the vending main units 30 of the work mode status of the bill accepter 20. 0017 FIG. 2 is a circuit block diagram of the second trigger mode according to the present invention. The power control circuit 10 is electrically connected between a bill accepter 20 and a plurality of vending main units 30, comprising a trigger 11, and a driver 12. 0018 Referring to FIGS. 2 and 3 again, when the vending main units 30 not triggered (the respective press-buttons are off), the bill accepter 20 is changed from the work mode to the stand-by mode. The flow of changing from the work mode to the stand-by mode is outlined hereinafter. The diode D detects the potential level of PIN OUT. When high potential of PIN OUT detected, PIN6 of the D-type flip-flop (U1) 111 of the trigger 11 is triggered by means of a low potential, causing PIN5 of the D-type flip-flop (U1) 111 of the trigger 11 to be changed from high potential to low potential. The low potential signal is then passed from PIN5 of the D-type flip-flop (U1) 111 of the trigger 11 through the N-channel field effect transistor (Q2) 121 to the P-channel field effect transistor (Q3) 122, thereby causing the P-channel field effect transistor (Q3) 122 to stop main power supply from passing to the bill accepter 20, and therefore the bill accepter 20 enters the power-saving stand-by mode. 0019 When one vending main unit 30 is triggered (switched on), a pulse is sent through PIN OUT to trigger PIN1 of the D-type flip-flop (U1) 111 of the trigger 11, thereby causing PIN5 of the D-type flip-flop (U1) 111 of the trigger 11 to be changed from low potential to high potential, which high potential is ten sent through the N-channel field effect transistor (Q2) 121 of the driver 12 to the P-channel field effect transistor (Q3) 122, thereby causing the P-channel field effect transistor (Q3) 122 to be turned on to let main power supply pass to the bill accepter 20, and therefore the bill accepter 20 enters the work mode. 0020 FIGS. 4 and 4A show the operation flows of the present invention. When the bill accepter started, it runs subject to the steps as follows: 0021 401 Power supply turned on; 0022 402 System initialization; 0023 403 Determine if the system functions normal or not And then proceed to step 404 if positive, or step 409 if negative; 0024 404 Determine if bill accepter has been jammed or not And then proceed to step 405 if jammed, or step 407 if not jammed; 0025 405 Send working messaging to vending main unit, and then proceed to step 406; 0026 406 Enter troubleshooting mode (see FIG. 6); 0027 407 Send working messaging to vending main unit, and then proceed to step 408; 0028 408 Enter stand-by mode (see FIG. 5); 0029 409 Determine whether vending main unit has been connected And then proceed to step 412 if connected, or step 410 if not connected; 0030 410 Determine if to change stand-by mode to work mode or not And then proceed to step 412 is positive, or step 411 if negative; 0031 411 Be ready to enter stand-by mode, and then proceed to step 409; 0032 412 Wait for insertion of bill, and then proceed to step 413; 0033 413 Determine whether there is any bill to be accepted And then proceed to step 415 if positive, or step 414 if negative; 0034 414 Be ready to enter power-saving mode, and the proceed to step 413; 0035 415 Accept inserted bill, and the proceed to step 416; 0036 416 Determine whether inserted bill has been delivered into position And then proceed to step 418 from S2 if positive, or step 417 if negative; 0037 417 Enter bill rejection mode (see FIG. 6); 0038 418 Determine whether vending main unit has been connected And then proceed to step 419 if positive, or step 425 if negative; 0039 419 Determine if vending main unit has been allowed to accept bill or not And then proceed to step 420 if positive, or step 428 if negative; 0040 420 Inform vending main unit of the value of bill, and then proceed to step 421; 0041 421 Determine whether vending main unit has been informed to wait for transaction And then proceed to step 422 if positive, or enter step 426 from S3; 0042 422 Determine whether vending main unit has informed to accept bill or not And then proceed to step 423 if positive, or step 428 if negative; 0043 423 Send bill to money box, and then proceed to step 424; 0044 424 Inform vending main unit of completion of bill acceptance procedure, and then enter step 412 from S1; 0045 425 Determine whether waiting time is up And then proceed to step 428 if positive, or step 418 if negative; 0046 426 Determine whether to wait for the connection of vending main unit or not And then enter step 421 from S4 if positive, or proceed to step 427 if negative; 0047 427 Determine whether communication time is over And then proceed to step 428 if over, or enter step 421 from S4 if not over; 0048 428 Enter bill rejection mode (see FIG. 6). 0049 FIG. 5 illustrates the flow of the stand-by mod. When the bill accepter entering the stand-by mode, it runs subject to the steps as follows: 0050 501 Start stand-by mode; 0051 502 Determine whether vending main unit has sent enable command or not And then proceed to step 503 if positive, or step 505 if negative; 0052 503 Determine whether vending main unit has stopped communication And then proceed to step 504 if positive, or step 507 if negative; 0053 504 Determine if communication ended And then proceed to step 506 if communication ended, or step 507 if not; 0054 505 Determine whether bill accepter has power-saving mode And then proceed to step 506 if positive, or step 504 if negative; 0055 506 Enter stand-by mode; 0056 507 Leave from stand-by mode. 0057 Referring to FIG. 4, which illustrates the operation flow of the present invention when the bill accepter started, and FIG. 6, which illustrates the operation flow of the bill rejection mode. When entered the bill rejection mode, it runs subject to the steps as follows: 0058 601 Start bill rejection mode; 0059 602 Determine if bill has been rejected or not And then enter step 412 from S1, or proceed to step 603; 0060 603 Eliminate bill jam problem, and then proceed to step 604; 0061 604 Determine whether bill is still jammed And then proceed to step 605 if positive, or step 606 if negative; 0062 605 Be ready to enter stand-by mode; 0063 606 Determine if bill jam problem can be eliminated or not And then proceed to step 605 if bill jam problem cannot be eliminated, or step 607 if bill jam problem can be eliminated; 0064 607 Eliminate bill jam problem; 0065 608 Determine whether bill rejection is done And then enter step 412 from S1 if positive, or proceed to step 606 if negative. 0066 As indicated above, when the bill accepter 20 or one vending main unit 30 generated a trigger signal, the bill accepter 20 immediately returns from the stand-by mode to the work mode. When runs idle, the power control circuit 10 cuts off power supply from the bill accepter 20, keeping the bill accepter 20 in the power-saving stand-by mode. 0067 A prototype of power control circuit for use in a vending machine has been constructed with the features of the annexed drawings of FIGS. 1-6. The power control circuit for use in a vending machine functions smoothly to provide all of the features discussed earlier. 0068 Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims.