Vacuum cleaner

A vacuum cleaner has a blower motor; a dust detector responsive to a sucked dust particle due to rotation of the blower motor for producing a dust detecting signal when each of the dust particles is detected passing a portion in a suction passage; counter responsive to the dust detection signal for counting the number of the dust interception particles for a given interval; and input power controller responsive to an output signal of the counter for controlling the input power of the blower motor by selecting an input power value from plural preset input power values in accordance with the number. Controlling input power may be performed in accordance with a pulse width indicative of the dust particle size or the counted number may be modified by pulse width. Another embodiment of the vacuum cleaner has plural light emitting diodes for indicating the number counted to show an operator uncleanliness of the floor. The controller includes a microprocessor which can control a thyristor provided in series with the blower motor directly. In a vacuum cleaner where the thyristor is located in the housing, the microprocessor may be located in a handle portion, and a D/A converter and a phase control circuit may be provided in the housing.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to a vacuum cleaner. 
2. Description of the Prior Art 
A vacuum cleaner is known which comprises a dust sensor provided in a 
passage for sucking air and a controlling circuit for controlling the 
suction force in accordance with a detection signal from the dust sensor. 
Such prior art vacuum cleaner is described in U.S. Pat. No. 4,801.082. 
However, in the above-mentioned prior art vacuum cleaner, the suction 
force is changed stepwise between high and low values. Thus, there is a 
drawback that the suction force is not proportionally varied with the 
degree of uncleanliness of the floor, i.e., the amount of dust to be 
sucked so that the suction force increases excessively if uncleanliness 
exceeds a given level. 
SUMMARY OF THE INVENTION 
The present invention has been developed in order to remove the 
above-described drawbacks inherent to the conventional vacuum cleaner. 
According to the present invention there is provided a vacuum cleaner 
comprising: a blower motor; a dust detector responsive to a dust particles 
sucked by to rotation of the blower motor for producing a dust detection 
signal when the dust particles pass through a portion of a suction passage 
a counter responsive to the dust detection signal from the dust detector 
for counting the number of dust particles for a given interval; and an 
input power controller responsive to an output signal of the counter for 
controlling input power of the blower motor in accordance with the number. 
According to the present invention there is also provided a vacuum cleaner 
comprising: a blower motor; a dust detector responsive to dust particles 
sucked by rotation of the blower motor for producing a dust detection 
signal when the dust particles pass through a portion of a suction 
passage; a pulse width detector responsive to a dust detection signal from 
the dust detection means for detecting the pulse width of the dust 
detection signal; and an input power controller responsive to an output 
signal of the counter for controlling input power in accordance with the 
width of the pulse. 
According to the present invention there is further provided a vacuum 
cleaner comprising: a blower motor; a dust detector responsive to dust 
particles sucked by rotation of the blower motor for producing a dust 
detection signal when the dust particles pass through a portion of a 
suction passage; a counter responsive to a dust detection signal from the 
dust detector for counting the number of the dust particles for a given 
interval; a pulse width detector responsive to a dust detection signal 
from the dust detector for detecting the width of a pulse caused by a dust 
particle passing the portion; and on input power controller comprising a 
modify circuit responsive to output signals of the counter and the pulse 
width detector for controlling input power of the blower motor in 
accordance with the number modified by the width. 
According to the present invention there is further provided a vacuum 
cleaner comprising: a housing having: a blower motor; an input power 
controller responsive to a control signal for controlling input power of 
the blower motor; and a handle portion having: a dust detector responsive 
to a dust particles sucked by rotation of the blower motor for producing a 
dust detection signal when the dust particles passing through a portion of 
a suction passage; and a counter responsive to the dust detection signal 
from the dust detector for counting the number of the dust particles for a 
given interval to produce a control signal indicative of the number of 
dust particles.

DETAILED DESCRIPTION OF THE INVENTION 
Referring now to the drawings. FIG. 1 is a cross-sectional view of an 
optical dust detection portion and FIG. 2 is a block diagram of a dust 
detection circuit for a first embodiment of the invention. FIG. 4 is a 
block diagram of the first embodiment which is common to the first through 
sixth embodiments of the invention. 
In FIG. 1, a light emitting device (LED) 8 and light sensitive device 4 are 
provided on a portion of suction passage 2 where a dust particle 1 passes. 
The light emitting device 3 and light sensitive device 4 face each other. 
The light emitting devices and light sensitive devices 4 are supported by 
respective transparent holders 5, which are provided for shielding air and 
light transmission. FIG. 2 is a schematic circuit diagram of a dust 
detection circuit 13. In FIG. 2, a current is provided to the light 
emitting device 3 through a resistor 6 from a dc power supply. To 
continuously power the light emitting device 3. The light sensitive device 
4 (hereinbelow referred to as a phototransistor) receives the light signal 
from the light emitting device 3. A collector terminal of the 
phototransistor 4 is connected to and biased by a resistor 7. The 
collector output of the phototransistor 4 is coupled to a minus input of 
an amplifier 9 through a capacitor 8 for cutting off a direct current. A 
plus input of the amplifier 9 is connected to a reference potential 10. 
Therefore, the amplifier 9 produces an output signal varying around 
potential E.sub..quadrature. of a reference voltage 10 wherein only the 
variation of collector potential of the phototransistor 4 (ac component) 
is amplified. A minus input terminal of a comparator 11 is connected to an 
output terminal of the amplifier 9. A plus input thereof is connected to a 
reference potential 12. An analog output signal of the amplifier 9 is 
compared with the reference potential E.sub.1 for waveform shaping. The 
operation of the above-mentioned structure is described hereinbelow. 
When a dust particle 1 passes across a light path between the light 
emitting device 3 and phototransistor 14, the light path between the light 
emitting device 3 and phototransistor 4 is interrupted, so that the base 
current of phototransistor 4 decreases and, thus, its collector potential 
increases. A potential changing component with variation in light 
intensity is amplified through the capacitor 8 around the reference 
potential E.sub..quadrature. to detect the light intensity change by the 
dust particle 1 as an analog signal. When the detected analog signal 
decreases under the reference potential E.sub.1, an output signal of the 
comparator 11 changes to H. As mentioned, the analog signal indicative of 
light intensity change is converted into a digital signal, i.e., a pulse 
signal or dust detection signal, is generated, with the following 
correlation. The dust detection signal indicates interception of the light 
path between the light emitting device 3 and phototransistor 14. 
When a small dust particle passes across the light path, the width of a 
pulse, such as pulse 101 of FIG. 3 is short. This is because the time 
interval necessary for the dust particle to pass through the light path is 
short. On the other hand, in the case of a large dust particle, for 
example, a paper scrap, the width of the pulse, such as pulse 102 of FIG. 
3, is large. Moreover, the change of dust count correspondingly indicates 
a relative change of the density of dust passing through the suction 
passage 2 as there is an increasing function between the dust count per 
unit of time interval T and the density of dust passing through the 
suction passage 2. This is due to the fact that although the dust sensor 
13 cannot distinguish individual ones of the plurality of dust particles 
passing through the light beam from the emitting diode 1 to the 
photodetector 2 at the same instant of time, the probability of the dust 
particles passing through the light beam overlapping each other is 
considered constant and there is a relationship between the dust density 
and the number of times the light path between the light emitting device 3 
and the photodetector 14 is intercepted by at least a dust particle. 
FIG. 4 is a block diagram of a vacuum cleaner using the above-mentioned 
dust detection circuit 13. In FIG. 4, the pulse signal produced by the 
dust detection circuit 13 is inputted into a microprocessor 14 as a 
control means. The microprocessor 14 counts the pulses in response to the 
dust detection signal from the dust detection circuit 13 and detects the 
number of pulses inputted for a given time interval T. For example, as 
shown in FIG. 5A, for a waveform of the dust detection signal, five, two, 
and four pulses are inputted for successive given time interval T 
respectively. In FIG. 5A, T is about 0.1 seconds. The microprocessor 14 
selects input power values for the blower motor 10 from P.sub.1 .about.Pn 
in accordance with the count number n of pulses inputted for the given 
interval, the pulse counts n are shown in FIG. 5B, which represents a data 
table stored in the ROM of the microprocessor 14 The microprocessor 14 
controls a gate of a bi-directional thyristor 15 through a transistor Q1 
responsive to port A thereof. M microprocessor 14 operates in response to 
the dust detection signal and an output signal of a zero-cross detection 
circuit 103 to control the input power to a blower motor 16 by phase 
controlling, as shown in FIG. 5C. according to a program stored in the 
microprocessor 14. The zero-cross detection circuit 103 detect when ac 
line voltage crosses zero volts. In most foreign countries, including such 
as for example Japan for whence the inventors conceive the instant 
invention, it is well known that the frequency of the AC line voltage is 
50 Hz. In Japan, however, the frequency and the AC line voltage could be 
either 50 Hz or 60 Hz, depending on whether it is the eastern portion (50 
Hz) or the western portion (60 Hz) of Japan. 
As shown in FIG. 6A, the microprocessor 14 operates as follows. 
When an operator turns on the vacuum cleaner, the microprocessor 14 
initializes. For example it clears a memory resets thyristor 15 and sets 
an initial time interval value for time TM1. Timer TM1 produces timer 
interrupts. Microprocessor 14 further enables the zero-cross interrupt and 
interrupt INT1 in an unshown main routine. Then microprocessor 14 waits 
for interrupts in the main routine. In response to an output signal of the 
zero-cross detection circuit 103, the microprocessor 14 starts zero cross 
interrupt at step 110 shown in FIG. 6A. In response to the dust detection 
signal, the microprocessor 14 starts interrupt INT1 processing 130 shown 
in FIG. 6B and counts the number of dust particles DC in step 131. 
Processing then returns to the main routine. In response to a timer 
interrupt timer INT starts in step 150, as shown in FIG. 6c and in the 
next step 151, the microprocessor 14 turns on thyristor 15. 
At every zero-crossing of ac line voltage, as for example for an AC line 
voltage operating at 50 Hz, the microprocessor 14 effects a zero-cross 
interrupt in step 110. In the following step 111, the microprocessor 14 
turns off thyristor 15 and sets a timer TM1 to +L. Timer TM1 is built in 
the microprocessor 14. Then, the timer TM1 is initiated. This causes a 
timer TM1 interrupt when the interval corresponding the initial value set 
in the main routine has passed. In the succeeding step 112 the 
microprocessor 14 counts the time count TC, which is indicative of the 
number of zero-crossing of ac line voltage. In the next step, a decision 
is made as to whether time count TC exceeds a reference value RT1. If the 
time count TC does not exceed RT1, processing returns to the main routine. 
If the time count TC1 exceeds RT1, processing proceeds to step 114. This 
means that the time interval for counting the number of dust particles has 
passed. In step 114, a decision is made as to whether the dust count DC 
exceeds a reference value R1. If the dust count DC exceeds a reference 
value R1, input power constant P1 is set to a variable P in step 118; and 
the microprocessor 14 subtracts P from one to obtain an off-interval 
t.sub.1 of the thyristor 15. Thus, interval t1 shown in FIG. 5C is changed 
in accordance with dust count DC. If the dust count DC does not exceed R1, 
processing proceeds to step 115. In succeeding steps 115 and 116, a 
decision similar to the step 114 is made. A correspondingly given input 
power constant P1, P2, P3, or P4 is set to the variable P where R1&gt;R2&gt;R3 
and P1&gt;P2&gt;P3&gt;P4. Thus, the greater the number of dusts detected for a 
given interval, as indicated by time count TC1, the larger the input power 
for the blower motor 10. In the succeeding step 121 of steps 118, 110, 
120, and 117, the microprocessor 14 clears dust count DC and time count 
TC1 Then processing returns to the main routine. Thus, the thyristor 15 is 
turned off in step 111 and turned on in step 151; and the interval t1 
indicative of off-state is determined (1-Pl), (1-P2), and (1-P) in 
accordance with the number of dust detected for the given interval. 
Hereinbelow will be described a second embodiment of a vacuum cleaner. 
Structure of the second embodiment is basically the same as the first 
embodiment. The only difference is that processing is executed in 
accordance with the flow chart of FIG. 8. FIGS. 7A and 7B show control of 
a second embodiment of the invention. The microprocessor 14 counts the 
pulses of the pulse signal generated by the dust detection circuit 13 for 
a given interval T. The microprocessor 14 changes input power for the 
blower motor 16 in accordance with the number of the counted pulses and 
changes the time interval of for maintaining respective input power values 
correspondingly. 
In an example of FIG. 7A, input power of a given value is maintained for an 
interval Wa corresponding to the four pulses inputted for a first interval 
T because four pulses are generated for the first interval T. In an 
example of FIG. 7B, a given input power is maintained for an interval Wb 
corresponding to two pulses because two pulses are generated for the first 
interval T. An interval W where Wa&gt;Wb is maintained, so that the 
microprocessor 14 controls interval W such that the larger the number of 
pulses generated, the longer the maintaining interval. 
Processing is executed in accordance with a flow chart of FIG. 8. However, 
basic operation is the same as the first embodiment and there are 
differences in steps 161-167. The main routine and interrupt routines are 
basically the same as the first embodiment. The only different portions 
are described hereinbelow. 
In FIG. 8, after processing of steps 117, 118, 119, and 120, steps 163, 
164, 165, and 167 are added respectively. In these steps, the 
microprocessor 14 set the time count to W1-Wn, respectively. On the other 
hand, step 161 is provided between steps 112 and 113. A decision is made 
in step 162. These steps detect when the interval for maintaining a 
determined input power has passed. Thus, input power determined in steps 
117-120 is maintained for interval W1-Wn in accordance with the number of 
dust particles. indicators amount. 
FIG. 9 shows control of a third embodiment of the invention. The 
microprocessor 14 changes preset values of input power for the blower 
motor 16 by detecting pulse width and the number of pulses of the pulse 
signal generated by the dust detection circuit 13, the pulse width varying 
in accordance with size of dust. 
In other words, input power for the blower motor 16 is set in accordance 
with the number of detected pulses generated for a given interval T. The 
number of dust particles is compensated by pulse width information. For 
example, the number n of detected pulses is multiplied by a pulse width 
compensation factor k. The result is used for setting input power of the 
blower motor 16. For example, when a dust particle of large size is sucked 
and a pulse with large width is detected, the number of pulses detected is 
compensated by information of the pulse width, so that the number of 
pulses is set to the equivalents of several pulse counts. Thus, suction 
force is increased considerably, so that a large suction force is effected 
for a large size dust particle. 
Basic processing is carried out according to the flow chart of FIG. 6A and 
the processing shown in FIG. 10 of a flow chart is executed between steps 
112 and 113 of FIG. 6A. The basic operation is the same as the first 
embodiment. Only the portion that is different is described hereinbelow. 
Processing starts at step 201 followed by step 112. In step 201 a decision 
is made as to whether dust detection output signal is H. If the dust 
detection signal is H. processing proceeds to step 202. In step 202 the 
microprocessor 24 increases a count PWC which indicates pulse width 
because during H step of the dust detection signal, this count is 
increased at every zero-cross interrupt. Processing proceeds to step 112 
of FIG. 6A. In step 201, if the dust detection signal is L, processing 
proceeds to step 203. In step 208, the microprocessor 14 compensates the 
dust count DC with the count PWC of pulse width count. For example, the 
number n of detected pulses is multiplied by pulse width compensation 
factor k. In the following step 204 the microprocessor 14 clears count 
PWC. 
FIG. 11 shows a fourth embodiment of the invention. The flow chart of FIG. 
11 is used in place of the flow chart of FIG. 6B. Thus, the main routine 
and other interrupt routines are the same as the first embodiment. In FIG. 
11, in response to the dust detection signal, interrupt processing starts. 
In step 302, an interrupt is performed. The interval of the interrupt is 
several milliseconds. Then, in next, step 303, the microprocessor 14 
detects whether the dust detection signal is H or L. If the dust detection 
signal is H. the detection signal is true. Thus, in the following step 
304, the microprocessor 14 counts the dust count DC. On the other hand, if 
the dust detection signal is L, the detected signal is not true, i.e.. a 
noise. Thus, the counting of dust is not performed and processing returns 
to the main routine directly. 
FIG. 12A shows a waveform of a dust detection signal In FIG. 12B, a noise 
component detected by comparator 11 in FIG. 12A is removed. 
FIGS. 13A and 13B show control of a fifth embodiment of the invention. In a 
vacuum cleaner of the fifth embodiment, to recover its rotating speed to 
the rotating speed set prior to the detection of dust, a stepwise slowing 
down of the rotation speed is effected. Accordingly, the rotating speed is 
changed at every predetermined intervals by a given predetermined value to 
gradually return to the initial rotating speed. In FIG. 13A, when dust is 
detected, the rotating speed of the blower motor 16 is increased to a 
level 20 from an initial rotating speed 19. After a predetermined 
interval, for example one second, has passed, the rotating speed is 
decreased to a level 21. Next, after the rotating speed is maintained for 
a second interval, for example one second,. the rotating speed is further 
decreased to a level 22. The rotating speed is returned to the initial 
level 10 one second after. In other words, in this embodiment, the 
microprocessor 14 controls the rotating speed such that the rotating speed 
is changed from an initial value to another value; then maintains the 
another value for a given interval; and further repeatedly changes the 
rotating speed from the another value to yet another given value for each 
given intervals until the rotating speed returns to the initial value. 
Moreover, as shown in FIG. 13B. if dust is detected within the interval 
where the rotating speed is maintained at the level 22, it is possible to 
increase the rotating speed to level 20 again. 
FIG. 14 shows a flow chart for realizing the above-mentioned embodiment. 
Processing starts at step 401 when an operator turns on the vacuum cleaner 
after initializing (not shown) step is executed. In step 401, the 
microprocessor 14 sets initial rotating speed IRS to a rotating speed RS. 
Next, in step 402, a decision is made as to whether a dust particle is 
detected. If a dust particle is detected, processing proceeds to step 403. 
In step 403, the microprocessor 14 increases rotating speed RS Next, in 
step 404, processing waits for interval WI. i.e., one second. If a dust 
particle is not detected, processing proceeds to step 404 directly. In the 
following step 405, the microprocessor 14 decreases rotating speed RS. 
Next, in step 406 a decision is made as to whether rotating speed RS is 
equal to the initial rotating speed. If rotating speed RS is equal to the 
initial rotating speed, processing proceeds to step 402. If rotating speed 
RS is not equal to the initial rotating speed, processing proceeds to step 
407. In step 407, the microprocessor 14 detects dust. If there is no dust, 
waiting of one second is performed in steps 408 and 409. When one second 
has passed, processing proceeds to step 405 and decreases rotation speed 
again. This routine is repeated until rotating speed RS equals the initial 
rotating speed. Rotating speed is controlled by steps 111 of zero-cross 
interrupt shown in FIG. 6A and interrupt INT1 of FIG. 6B and basic 
structure is shown in FIG. 4. 
FIG. 15 shows a sixth embodiment of the invention. The microprocessor 14 
turns off input power of the blower motor 16 shown in FIG. 4 by a 
controlling gate of the thyristor 15 when the dust detection circuit 18 
does not detect dust for a given interval. Processing is executed in 
accordance with a flow chart of FIG. 15. In FIG. 15, processing starts in 
step 501 where the microprocessor 14 resets and starts a timer TM2 
provided in the microprocessor 14. In the following step 502, a decision 
is made as to whether dust is detected. If dust is detected, processing 
returns to step 501. If dust is not detected, processing proceeds to step 
503. In step 503, a decision is made as to whether time interval T2 
exceeds a predetermined value T1. If time interval T2 exceeds the 
predetermined value T1, the microprocessor 14 cuts off input power of the 
blower motor 10. If time interval T2 does not exceed the predetermined 
value T1, processing returns to step 502. As mentioned above, in the 
vacuum cleaner of the sixth embodiment, input power of the blower motor 16 
is turned off if dust is not detected for a given time interval. 
FIG. 16 shows a seventh embodiment of the invention. In FIG. 16, the basic 
structure of the seventh embodiment is the same as that of the first 
embodiment. There is a difference that plural indication elements (LED) 27 
are connected to ports B.sub.1 -B.sub.n respectively, of the 
microprocessor 14. The indication elements 27 are supplied with dc current 
through current limiting resistors 28. Processing of this embodiment, 
shown in FIG. 17, is basically the same as that of the first embodiment. 
There is a difference that after steps 117-120, the microprocessor 14 
turns on either ports B.sub.1 -B.sub.n in accordance with dust count DC 
through judging steps 114-116. Therefore, the degree of the dust count is 
indicated by the indictors 27 to show degree of uncleanliness of the 
floor, i.e., dust amount 
FIG. 18 shows an eighth embodiment of the invention. The structure of this 
embodiment is basically the same as that of the seventh embodiment. There 
is a difference that the thyristor 15 is controlled by the microprocessor 
14 through a power control circuit 41 and the output port B is connected 
to a D/A converter. Thus, the microprocessor 14 outputs dust count DC at 
the output port B of the microprocessor 14 similar to the seventh 
embodiment The dust count DC of digital signal is converted into analog 
signal by the D/A converter 40. The output of the D/A converter is 
compared with a triangular wave from a triangular wave generator 43 by a 
comparator 42. Output of the comparator controls the duty of turning on 
the thyristor 15. The microprocessor 14 executes the process shown in FIG. 
17 in response to zero-cross detection circuit 13 and the dust detection 
circuit 13. In the seventh embodiment, dust count outputted at the port B 
of the microprocessor 14 is used for indication of dust. On the other 
hand, in the eighth embodiment, the output signal of the ports B.sub.1 
-B.sub.n is used for controlling of the thyristor 15. The above-mentioned 
structure is provided for by separating a driving unit from a control 
unit. The driving unit comprises the D/A converter 40, power control 
circuit 41 and the thyristor 15 and blower motor 16 provided to a housing. 
The control unit comprises the microprocessor 14, dust detection circuit 
13, and zero-cross detection circuit 17 provided in a handle portion of 
the vacuum cleaner.