Patent Application
20070266520
Various exemplary embodiments of the invention will be described in detail, with reference to the following figures, wherein:
The various exemplary embodiment of the present invention are directed to a vacuum cleaner that includes a motion detector that is used to activate and deactivate a brush roll disposed within the vacuum cleaner nozzle head. When the vacuum is detected as being in motion, motion detecting logic is used to keep the brush roll running or to initially activate the brush roll. When the vacuum is detected as being stationary, the motion detecting logic is used to deactivate the brush roll. Preferably, the deactivation of the brush roll is delayed for a brief period of time after the vacuum cleaner is detected to be stationary, and the activation of the brush roll is immediate after motion is detected. However, the present invention is not meant to be limited to this embodiment and, alternatively, motion control logic may be used that results in any variation of delayed and immediate activation and deactivation of the brush roll. Further, although the embodiment of the present invention disclosed herein is directed to an upright vacuum cleaner, it should be appreciated that the present invention is not meant to be limited to any particular vacuum cleaner type.
A motion sensor assembly, generally designated by reference number 24, is disposed adjacent to one of the wheels 22. The motion sensor assembly 24 includes a number of detectable indexes 26 disposed equally spaced around the inner circumference of the wheel 22 and a stationary motion detector 28 disposed adjacent to the wheel 22, so that the indexes 26 are consecutively aligned in face-to-face relation to the motion detector 28 as the wheel 22 rotates. The indexes 26 may be, for example, magnetic disks. The motion detector 28 is preferably a Hall-effect sensor element. In other embodiments of the invention, the motion sensor assembly 24 may include alternative sensor components, such as, for example, a brush-contact switch, a magnetic reed switch, an optical switch, or a mechanical switch. Also, depending on the type of motion detector used, the indexes 26 may be gaps, notches, or contacts, or the indexes 26 may be replaced with a single element, such as, for example, a cam lobe. In general, the present invention is not meant to be limited to a particular type of motion detector assembly, and any known or later discovered motion detector is suitable for use with the present invention.
The motion sensor assembly 24 is electrically connected to a control unit 30. The control unit 30 receives signals from the motion sensor assembly 24, and based on the signals controls the operation of the brush roll drive motor 50. As explained in further detail below, the control unit 30 may include circuitry that controls the brush roll drive motor 50 such that the brush roll 40 is driven by the drive motor 50 when the vacuum wheels 22 are in motion and the brush roll 40 is not driven by the drive motor 50 when the vacuum wheels 22 are stationary.
Because it takes time for capacitor C1 to charge or discharge through R2, the voltage on Pin 2 of the XOR gate is delayed for a few milliseconds. The previous logic state of the switch U1 is thus stored in capacitor C1 for a short period of time. Whenever the switch U1 changes from high to low, Pin 1 of the XOR gate immediately goes low but Pin 2 remains high and begins to go low as capacitor C1 discharges through R2. For the short period of time when Pin 2 is high and Pin 1 is low, the output at Pin 3 of the XOR gate goes high briefly until Pin 2 goes low. Similarly, if the switch U1 changes from low to high, Pin 1 of the XOR gate immediately goes high but Pin 2 remains low and begins to go high as capacitor C1 charges through R1 and R2. Again, for the short period of time when Pin 2 is low and Pin 1 is high, the output at Pin 3 of the XOR gate goes high but returns low as capacitor C1 charges and provides logic 1 on Pin 2.
The output at Pin 3 of the XOR gate momentarily pulses from low to high each time the switch U1 either opens or closes. The output of the XOR gate could be used to reset a digital timer, or to reset a timing circuit as shown in the right-hand portion of the circuit 60. Whenever the output of the XOR gate goes high, capacitor C2 is quickly charged up to about 4 volts through diode D1. Diode D1 only conducts when the output of the XOR gate is high but does not conduct if the capacitor is charged and the output of the XOR gate is low. Resistor R3 serves to discharge capacitor C2 very slowly. For example, capacitor C2 may discharge from 4 volts to 1 volt in about 2 seconds. Using a higher capacitance in C2 will provide a longer delay, so that 16 uF will provide about 4.5 seconds to discharge and 50 uF would take over 14 seconds to discharge. Comparator U3 has a reference voltage of +1 volt connected to Pin 2. This reference voltage could come from a voltage divider or other source. Whenever the voltage at Pin 3 of the comparator U3 is higher than the voltage on Pin 2, the output at Pin 1 will go high signaling to turn on the brush roll drive motor 50. If the voltage on Pin 3 of the comparator U3 is less than the voltage on Pin 2 of U3, the output at Pin 3 of the comparator U3 will go low signaling to turn off the brush roll drive motor 50. Resistor R3 and capacitor C2 form an RC timer circuit. The status of the timer is the output of comparator U3 which checks the charge voltage on capacitor C2. Thus, whenever the charge on C2 is greater than 1 volt (the reference voltage) wheel motion was detected recently and the brush roll drive motor 50 can remain on. If the charge on capacitor C2 is less than 1 volt, wheel motion was not detected recently and the brush roll drive motor 50 should be turned off.
Alternatively, the XOR gate function or transitions from one logic state to the other may be sensed using a microcontroller. The microcontroller can check the logic state at the junction of R1 and R2 frequently and a free-running counting-timer can be reset each time the switch U1 changes from high to low or from low to high. If the timer reaches a predetermined terminal count (i.e. a predetermined-amount of time passes without any movement of the wheels 22), the brush roll drive motor 50 is turned off. The brush roll drive motor 50 may be turned on when the timer is reset or has not reached the terminal count.
It should be appreciated that, in other embodiments of the present invention, the motor on/off signal does not need to directly control the brush roll motor. Instead, the signal could merely be a control input that is combined with other signal inputs that indicate other conditions that may supersede the motor on/off signal. For example, a malfunction, such as a jammed roller or broken belt, may be detected, in which case a signal indicating the malfunction may be generated that supersedes any motor on signal generated by the brush roll control device.
While the foregoing invention has been described in some detail for purposes of clarity and understanding, it will be appreciated by one skilled in the art from a reading of the disclosure that various changes in form and detail can be made without departing from the true scope of the invention in the appended claims.
