US3927726A

US3927726A - Digital display type weighing apparatus

Info

Publication number: US3927726A
Application number: US478868A
Authority: US
Inventors: Masanao Hanado; Kensi Takamoku; Tsutomu Miyoshi; Shien Tsai Jeng
Original assignee: Tanita Corp
Current assignee: Tanita Corp
Priority date: 1973-06-18
Filing date: 1974-06-13
Publication date: 1975-12-23
Anticipated expiration: 1992-12-23
Also published as: DE2429059A1; AU7017174A; FR2233609A1; FR2233609B1; GB1471320A; DE2429059B2; CA1016197A

Abstract

A pointer is movable proportionally to applied body-weight and has a servo-sensor controlling member attached to one end thereof. A driving plate is driven by a motor. A servo sensor is mounted on the driving plate and adapted to complete a shortcircuit of the motor when in a position opposite to the controlling member and complete an energizing circuit of the motor when not in said position. The motor is started after the pointer and the controlling member begin to go ahead of the servo sensor in response to application of the weight, completing the motor energizing circuit, and continues to drive the driving plate until the servo sensor is brought to a position opposite to the controlling member which has been stopped at a position corresponding to the applied weight, causing the completion of the short-circuit of the motor and thus a rapid stopping of the motor. A convertor converts the number of revolutions of the motor into a corresponding number of electric pulses. A counter circuit counts the pulses. A digital display receives the output of the counter circuit and provides a digital indication of the applied weight. The digital display may be adjusted for Japan, Europe and the United States of America.

Description

United States Patent 1191 Hanado et al.

[ Dec. 23, 1975 [54] DIGITAL DISPLAY TYPE WEIGHING APPARATUS [75] Inventors: Masanao Hanado, Kawasaki; Kensi Takamoku, Shimoigusa; Tsutomu Miyoshi; Shien Tsai Jeng, both of Tokyo, all of Japan [73] Assignee: Tanita Corporation, Tokyo, Japan [22] Filed: June 13, 1974 1 [21] Appl. No.: 478,868

[30] Foreign Application Priority Data Haackw. .1 177/164 Primary ExaminerL. T. Hix Assistant Examiner-Vit W. Miska 57 ABSTRACT A pointer is movable proportionally to applied bodyweight and has a servo-sensor controlling member attached to one end thereof. A driving plate is drlvenby a motor. A servo sensor is mounted on the driving plate and. adapted to complete a short-circu1t of the motor when in a position opposite to the controllmg member and complete an energizing circu t of the motor when not in said position. The motor is started after the pointer and the controlling member begm to go ahead of the servo sensor in response to applicanon of the weight, completing the motor energiz ng circuit, and continues to' drive the driving plate unt1l the servo sensor is brought to a position opposite to the control- "ling member which has been stopped at a position corresponding to the applied weight, causing the completion of the short-circuit of the motor and thus a rapid stopping of the motor. A convertor converts the number of revolutions of the motor into a correspondmg number of electric pulses. A counter circuit counts the pulses. A digital display receives the output of the counter circuit and provides a digital indication of the applied weight. The digital display may be ad usted for Japan, Europe and the United States of Amerlca.

15 Claims, 9 Drawing Figures U.S. Patent Dec.23, 1975 Sheet10f4 3,927,726

US. Patent Dec.23, 1975 Sheet20f4 3,927,726

U.S. Patent Dec.23, 1975 Sheet4of4 3,927,726

FIG.6B

f PTr FIG.7B

PGC

HSW

FIG.7A

[I E HSW M64 FIG.8

DCR

DIGITAL DISPLAY TY E WEIGHING APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a digital display type weighing apparatus, and particularly to such a weighing apparatus as adapted to measure human body-weight.

2. Description of the Prior Art In place of conventional analog display type weighing apparatus which employs a stationary scale disk and a rotatable pointer adapted to move above the scale disk an angular distance proportional to applied human body-weight, thereby providing a visual indication of the weight, or which utilizes a stationary pointer and a scale disk adapted to rotate with respect to the pointer through an angle proportional to applied human bodyweight, thereby providing a visual indication of the weight, digital display type weighing apparatuses have recently been proposed. Among them there is a weighing apparatus comprising a platform carrying the human body to be weighed and adapted to lower a distance proportional to the body-weight, a rotatable disk or cylinder adapted to move an angular distance proportional to the lowered distance and being provided at angular positions of its periphery with electric conductive markers having respective patterns representative of the respective angular position, a member for electromagnetically or mechanically holding the disk or cylinder immediately after stopped at the position according to the applied weight, brushes adapted to contact with the markers of the disk or cylinder, and a digital display for indicating the body-weight by means of an electrical signal as picked up by the brushes. There is also a weighing apparatus comprising a pointer adapted to move by a distance proportional to applied human body-weight, a light shielding piece attached to the forward end of the pointer, a photoelectric conversion device mounted on a plate driven by a motor, the photoelectric conversion device being adaptedto permit completion of a short-circuit around the motor when in a position opposite to the light shielding piece and to permit completion of a motor energizing circuit when not in the position, and a digital display drum adapted to be driven by the motor, whereby when the pointer and thus the light shielding piece begin to move ahead of the photoelectric conversion device in response to the applied body-weight, the photoelectric conversion device permits energization of the motor, thereby driving the plate to mechanically initiate the drum,and then the drum continues to be rotated until the pointer and thus the light shielding piece stop at a position distant proportionally to the applied weight and then the photoelectric conversion device is moved together with the plate to a position opposite to the stopped piece, permitting completion of the short-circuit to cause rapid de-energization of the motor, thereby one of the numerical marks arranged on the periphery of the drum is exposed to provide a visual digital indication of the applied weight when the drum stops finally.

ment displays of 0 and 0.5 being employed to represent a fraction of a kilogram. For these reasons, the weighing apparatus has the following shortcomings: it is necessary to make the, 16 brushes contact with the electric conductive markersunder uniform-pressures; it is necessary to take a measure to prevent suffering from severe environments such as dusty environment and humid environment. If the weighing apparatus is used in a bathroom, it will, be particularly necessary; and if a remote display is employed, it is necessary to provide a cord having at least 16 inner conductors leading to the display. Moreover, the latter weighing apparatus has the defects that the driven drum imposes a mechanical load on the motor; that cumbersome adjustments are required; and that a number of assembling steps are required, resulting in a expensive apparatus.

Therefore, it is an object of this invention to provide a novel weighing apparatus eliminating the defects as mentioned above. According to this invention, such a digital display drum as employed in the latter weighing apparatus is not provided. Instead, a pointer with a permanent magnet is provided, and a reed switch is mounted on a driverr plate. The pointer is deflected proportionally to applied human body-weight. A motor is provided to continue to drive the plate until.the reed switch reaches a position opposite to the permanent magnet of the pointer thus deflected. The number of rotations of the motor required to achieve this is converted into a corresponding number of electric pulses. The pulses are applied to a counter circuit for providing a digital indication of the body-weight on a digital display unit.

Incidentally, specifications of the digital display of weighing apparatus are different for Japan, Europe and the United States of America, as shown in Table 1. Because the sizes of the bodies of the Japanese, the Europeans and the Americans are different and the unitages of weight adopted in the respective zones are also different.

As seen from the above Table 1, the full scales of weighing apparatus must be different for Japan, Europe and U.S.A. In order to overcome the difference it is very difficult to modify a weighing apparatus made for the Japanese to suit the Europeans or the Americans having a larger body-size and a larger body-weight, from the viewpoint of the mechanism and accuracy of the apparatus. For this reason, it is almost impossible to internationally unify the specifications of weighing apparatus. Under the circumstances, the advent of a digital display device for weighing apparatus will be desired which is capable of being switched over to meet the requirements as prescribed in any country.

Therefore, it is another object of this invention to provide such a digital display device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of the main mechanism of the weighing apparatus according to this invention;

FIG. 2 is a schematic diagram of the electric circuit as used in the weighing apparatus of this invention;

FIG. 3(A) is a side view of a servo sensor comprising a light-emitting diode and a photodiode as used in the weighing apparatus of this invention;

FIG. 3(B) is a schematic diagram of a motor time delayed starting circuit employing the servo sensor of FIG. 3(A);

FIG. 4(A) is a side view of a servo sensor comprising a Hall switch;

FIG. 4(B) is a schematic diagram of a motor time delayed starting circuit utilizing the servo sensor of FIG. 4(A);

FIG. 5 (A) is a side view of a servo sensor comprising a magnetic reluctance element;

FIG. 5(B) is a schematic diagram of a motor time delayed starting circuit employing the servo sensor of FIG. 5(A);

FIG. 6(A) is a block diagram of a pulse generator comprising a light-emitting diode and a phototransistor;

FIG. 6(B) is a schematic diagram of thepulse generator circuit of FIG. 6(A); I

FIG. 7(A) is a block diagram of a pulse generator comprising a Hall switch and a rotatable magnet;

FIG. 7(B) is a schematic diagram of the pulse generator circuit of FIG. 7(A);

FIG. 8 is a block diagram of a digital display device as used in the weighing apparatus of this invention; and

FIG. 9 is a block diagram of a counter circuit controlled by a decorder.

7 DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 1, a pointer 1 can be rotated proportionally to applied human body-weight. In a usual manner, a pinion 2 is attached to the shaft of the pointer I. A rack 22 engages the pinion 2. The rack 22 is biased by a spring 21 attached to one end thereof in one direction. The other end of the rack 22 is pivoted on a rocking frame 26 with a weighing pin27. The weighing pin is carried upwardly by the upper surface of bent portions 24a of a pair of long links 24, which form a balancing link mechanism together with a pair of short links 23. Thus, a resistance to inclination of the rocking frame 26 is provided. In weighing operation, a main weighing spring 25 is expanded proportionally to a distance by which the balancing link mechanism lowers. The upper surface of the bent portions 24a: of the long links 24 is lowered in proportion to the expansion of the spring 25. This causes the rocking 26 frame to be inclined by the rack spring 21 to the extent that a balance is re-established, i.e. until the weighing pin 27 again contacts the lowered end 24a of links 24. This inclination of the rocking frame results in a movement of the rack 22 by the spring 21 to the right side (as viewed in FIG. 1). This movement causes the pinion 2 to be rotated. Thus, the pointer 1 is deflected to an angular position proportional to theapplied weight. The pointer l is provided at one end thereof with a magnetic shielding piece 11 which is made of, for example, a magnet such as Thermalloy or an alloy of nickel and iron.

A driving worm wheel 3 is loosely pivoted on the shaft of the pinion 2. The worm wheel 3 has worm teeth 31 on its peripheral surface and a pin P on its lower surface. The pin P is adapted to drive a leaf switch LFSW.

A servo sensor SS is mounted on the worm wheel 3, which servo sensor comprises a permanent magnet MG and a reed switch LDSW. The servo sensor SS is positioned so that a locus of rotation of the magnetic shielding piece 11 passes through between the permanent magnet MG and the reed switch LDSW. When not in use, the pointer 1 reads zero and the magnetic shielding piece 11 is between the permanent magnet MG and the reed switch LDSW, and the pin P engages the leaf switch LFSW to hold it in an off-condition.

An electric motor M is provided. A worm W is attached to one end of theshaft of the motor M. The worm W engages the worm wheel 3. A permanent magnet MG is mounted on the other end of the shaft of the motor M. A reed switch LDSW is arranged to be opposed to the permanent magnet MG Thus, the permanent magnet MG and the reed switch LDSW form a pulse generator PG.

This invention will be described in detail in connection with the mechanical structure of FIG. 1 and the electric circuit of FIG. 2.

FIG. 2 shows the electric circuit of the weighing apparatus of this invention when not in use and thus the pointer 1 reading zero. In this condition, no electric current flows from a power source E to any of a servo sensor circuitSSC, a delay circuit DLC for starting the motor M with a time delay, a pulse generating circuit PGC, a counter circuit CC, a resetting circuit RSC for the counter circuit CC and a holding circuit HDC for the counter circuit CC.

The servo sensor circuit SSC includes terminals t t, and t as connected to the power source E, a series circuit consisting of a relay RY and the reed switch LDSW as connected across the power source E, a terminal L, as connected to the holding circuit HDC, a terminal t,, as connected to'the short-circuit around the motor M, a switching contact ct as provided between the terminals t and t and driven by the relay RY and a switching contact ct as provided between the terminals t and t and driven by the relay RY.

As described in connection with FIG. 1, when a human body-weight is applied to the weighing apparatus, the pointer l with the magnetic shielding piece 11 begins to rotate in response to the application of the weight, and thus the shielding piece 11 goes away from between the reed switch LDSW and the permanent magnet MG. This permits the reed switch LDSW to be subject to the magnetic field of the permanent magnet MG and thus turn on. Then, the relay RY is energized by the power source E to drive the contact ct toward the terminal t thereby connecting the power source E to a terminal V,,,,. In this way, the voltage of the power source E is applied through the terminal V to the resetting circuit RSC. This causes a NOT circuit N Ot to produce only one pulse, depending upon a t me constant as determined by a resistor R and a capacitor C This pulse is applied to the counter circuit CC to initiate the automatic resetting of the counter circuit CC, thereby causing a display unit DSP to read zero. The display unit DSP has three display windows for digits of the first order, the second order and the first place of the decimal part of a number representative of the applied body-weight.

Since the contact ct is contacting with the terminal t the holding circuit I-IDC is maintained in a ,cut-off condition. Although the contact ct makes contact with the terminal t to complete an energizing circuit for the motor M, the motor M is not immediately started.

Namely, the motor M is not started until a transistor Tr, is made conductive after a time delay as based on the time constant of a capacitor C, and a resistor R, and then a transistor Tr is made conductive. Therefore, any possible vibration of the pointer 1 about a position at which the pointer is to be stopped can be damped out before the motor is started with the time delay. When the motor M is rotated, the worm W attached to the shaft of the motor M is rotated to drive the worm wheel 3. Then, the pin P goes away from the leaf switch LFSW, and thus the leaf switch is made contact with the terminal t,. Under this condition, the voltage of the power source E is applied to the terminal V regardless of whether or not the contact ct, is made contact with the terminal As mentioned above, the motor M is started with a time delay, and the worm W attached to the shaft of the motor M drives the worm wheel'3. The motor M continues to rotate until the reed switch LDSW and the permanent magnet MG of the servo sensor SS mounted on the worm wheel 3 are brought to a position opposite to the pointer I which has already been stopped at an angular position corresponding to the applied bodyweight, and thus the reed switch LDSW is turned off.

The turning off of the reed switch LDSW causes the relay RY to be de-energized. This makes the contact ct, return to the terminal t thereby the holding circuit HDC being turned on. On the other hand, the contact ct, is made contact with the terminal t to complete the short-circuit for the motor M, resulting in rapid stopping of the motor M.

The permanent magnet MG, attached to the other end of the shaft of the motor M rotates as the motor M does, The magnet MG, has a north pole N at one end thereof and a south pole S at the other end thereof, as shown in FIG. 2. Therefore, the magnet MG, makes the reed switch LDSW, of the pulse generator PG turn on twice per one revolution of the motor M, thereby two pulses being generated per one revolution of the motor M. The pulses are smoothed and shaped by the resistor R and the capacitor C of the pulse generating circuit PGC and thereafter are, applied through a NOR circuit NOR, to the counter circuit CC. In this embodiment, the number of the worm teeth 31 of the worm wheel 3 is 200, and the worm wheel 3 is designed to make one revolution for an applied weight of 100 kg. Namely, any one revolution of the motor M is adapted to cause the worm wheel 3 to be advanced its one tooth and thus 200 revolutions of the motor M makes one revolution of the worm wheel 3. Therefore, any two generated pulses represent 0.5 kg, and any one generated pulse represent 0.25 kg.

Such pulses are applied through the NOR circuit NOR, from the pulse generating circuit PGC to the counter circuit CC, and are counted in the counter circuit CC, as in a well-known manner. The count is converted into a number representative of applied weight, and the number is displayed on the display unit DSP. For example, the display unit has three display windows. One of the windows is for displaying a digit of the second order, kg order of a number representative of an applied weight, the second one is for displaying a digit of the first order, 1 kg order of the number, and the third one is for displaying a digit of the first place of the decimal part of the number,.or digit 0 or 5 depending upon a fraction of 1 kg. Available display systems include a segment'display system, a filament display system, a fluorescence display system, an incandescent wire display system, a discharge tube display system, a light-emitting diode display system, a liquid crystal display system and a plasma display system.

The display is maintained to indicate the applied body-weight until the servo sensor SS mounted on the worm wheel 3 is moved to a position opposite to the magnetic shielding piece and then the motor M is stopped.

When the motor M is thus stopped, the contact ct, is made contact with the terminal I, and thus the voltage of the power source E is applied through the terminal V to the holding circuit I-IDC. Specifically, the voltage is applied through the resistor R, and the capacitor C to the NOT circuit NOT The output of the NOT circuit NOt, is applied to the NOT circuit Nor and the output of the NOT circuit NO: is applied to one of the inputs of the NOR circuit NOR The output of the resetting circuit .RSC is applied to one of the inputs of a NOR circuit NOR which is connected to the NOR circuit NOR in a flip-flop form. When the high output of the NOT circuit NO: is applied to one input of the NOR circuit NOR the output of the NOR circuit NOR, becomes .low. This low output is applied to one input of the NOR'circuit NOR, and then the output of the NOR circuit NOR, becomes high. Because of this high output being applied to one input of the NOR circuit NOR,, the output of the NOR circuit NOR, becomes low, regardless of whether or not a pulse is applied to the other input of the NOR circuit NOR,. This prevents the output of the pulse generating circuit PGC from being applied to the counter circuit CC. Thus, the output of the counter circuit CC is held, and the display on the unit DSP is maintained to indicate the body-weight.

When the applied body-weight is removed, the pointer 1 with the magnetic shielding piece 11 is returned to zero position. The reed switch LDSW of the servo sensor SS then turns on to cause the relay RY to be energized, thereby the contacts ct, and ct, being made contact with the terminals 1, and t respectively. The motor M is restarted and the pulse generating circuit PGC generates pulses. However, the pulses are prevented frompassing to the counter circuit CC by the action of the NOR circuit NOR, in the holding circuit I-IDC. Therefore, at this time, the display on the unit DSP is still maintained to indicate the body-weight.

When the servo sensor SS is brought to a position opposite to the magnetic shielding piece 11 of the pointer 1 which has already been returned to zero position, the pin P engages the leaf switch LFSW to turn off it. The power sou'rceE is disconnected from the terminal VDD.

FIGS: 3, 4 and 5 illustrate modifications of the servo sensor SS. y I

In the servo sensor of FIG. 3(A), a light-emitting diode LD is arranged to be opposed to a phototransistor PTr. A light shielding piece 12 is attached to the pointer 1 instead of the magnetic shielding piece 11. A locus of rotation of the light shielding piece 12 passes through between the light-emitting diode LD and the phototransistor PTr. FIG. 3(8) shows a connecting circuit of the servo sensor of FIG. 3(A). In operation, when the light shielding piece 12 goes out of between the light-emitting diode LD and the phototransistor PTr, light from the diode LD incidents upon the phototransistor PTr. The phototransistor PTr then produces an output. The output makes a transistor Tr conductive, thereby the relay RY being energized to drive the contact ct, toward the terminal t Thus, the motor M is started with a time delay, as described in connection with FIG. 2. In FIG. 3(8), D, indicates a reverse-current blocking diode.

FIG. 4(A) shows the structure of a servo sensor comprising a Hall switch HSW and a magnetic shielding piece 13 attached to the pointer 1. In the Hall switch I-ISW, a pair of magnetic cores having a C-shaped section are connected at the free end of one leg thereof to the ends of a magnet MG so that the free ends of the other legs of the cores define a gap G. A Hall element HE is mounted on the free end of the leg of the lower core CR. The magnetic shielding piece 13 is adapted to pass through the gap G. FIG. 4(B) shows a connecting circuit of the servo sensor of FIG. 4(A). In operation, when the magnetic shielding piece 13 goes away from the Hall switch HSW, the Hall switch HSW is made conductive. Then, voltage drops develop across resistor r, and r,. This causes a transistor Tr to be made conductive, resulting in energization of the relay RY. Thus, the motor M is started with a time delay, in the same manner as described with regard to FIG. 3(B).

FIG. 5(A) shows the structure of a servo sensor comprising a transformer TF and a magnetic reluctance element 14 mounted on the pointer 1. In the transformer TF, a pair of magnetic cores having a C-shaped section are connected at the free end of one leg thereof to the ends of a magnet MG so that the free ends of the other legs of the cores define a gap G. The magnetic reluctance element 14 is adapted to pass through the gap G. FIG. 5(B) shows a connecting circuit of the servo sensor SS of FIG. 5(A). When the magnetic reluctance element 14 goes out of the transformer TF, the transformer TF is made conductive and thus voltage drops develop across a resistor r and a variable resistor r, as connected in series with the transformer TF. This causes a transistor Tr and thus a transistor T to be made conductive, resulting in time delayed starting of the motor M, as in FIG. 4(B).

FIGS. 6 and 7 illustrate modifications of the pulse generator PG.

In the pulse generator of FIG. 6(A), a light-emitting diode LD is positioned to be opposed to a phototransistor PTr. A disk R with apertures h is arranged between the diode LD and the phototransistor PTr. The disk R is driven by a motor M. These components are connected as shown in FIG. 6(B). When the disk R is rotated by the motor M, a pulse is generated between the terminals t and t connected to the collector and emitter of a transistor Tr every time any one of the apertures of the disk R is aligned with the light-emitting diode LD and then light from the diode LD incidents upon the phototransistor PTr, thereby the phototransistor PTr produces an output to cause the transistor Tr, to be instantaneously made conductive.

Referring now to FIG. 7(A), a magnet MG is provided to be opposed to a Hall switch HSW. The magnet MG is driven by a motor M. These components are connected as shown in FIG. 7(8). The Hall switch HSW turns on twice a revolution of the magnet MG A pulse is generated at the output of a pulse generating circuit PGC every time the Hall switch turns on.

An embodiment of a digital display device according to this invention will be described in detail with regard to FIGS. 8 and 9. In FIG. 8, CC indicates a counter circuit comprising five counters C C,, C C and C DSY indicates a display unit. In this embodiment, the display unit DSY has a display window D, for displaying a digit of the decimal part of a number representative of measured body-weight, a display window D, for displaying the unit digit of the same, a display window D for displaying the tenth digit of the same, and a display window D for displaying the hundredth digit of the same.

The counter C receives the pulses produced when the motor M is rotated according to the deflection of the pointer 1 proportional to applied body-weight. The counter C, controls the count output from the counter C As described before, the full scale of weighing apparatus is different from Japan, Europe and U.S.A. However, all of Japan, Europe and U.S.A. prescribes that weighing apparatuses are designed wherein the full scale corresponds to when the pointer 1 makes one revolution, for example when the driving plate 3 with the servo sensor SS as driven by the motor M makes one revolution, following up the controlling member 1 1 attached to the pointer 1.

According to this invention, the total number of revolutions of the motor M necessary to rotate the driving plate 3 by one revolution is 200 all for Japan, Europe and U.S.A. In addition to this, the number of pulses produced per one revolution of the motor is 4 for Japan and Europe, 3 for U.S.A. This is shown in Table 2.

As seen from the above Table 2, in weighing apparatuses for Japan and Europe 800 pulses are produced when the motor M makes 200 revolutions required to rotate the driving plate 3 by one revolution, and in weighing apparatuses for U.S.A. 600 pulses are produced when the motor M makes 200 revolutions. These pulses P are applied to the counter C The counter C is selected to be of the quaternary type for Japan, of the trinary type for Europe, and of the binary type for U.S.A. More specifically, for Japan the counter C outputs one pulse to the counter C, at the next stage every time the counter C receives any four successive pulses. For Europe, the counter C outputs one pulse to the counter C, at the next stage very time the counter C receives any three successive pulses. For U.S.A. the counter C outputs one pulse to the counter C, at the next stage every time the counter C receives any two successive pulses. The counter C, is selected to be of the binary type for Japan and Europe, and of the denary type for U.S.A. More specifically, for Japan and Europe the counter C, outputs one pulse to the counter C at the next stage every time the counter C, receives any two successive pulses. For U.S.A. the counter C, outputs one pulse to the counter C, at the next stage every time the counter C, receives any ten successive pulses.

Table 3 shows the maximum numbers of pulses indicating weight by Kg or Lbs into which the total numbers of pulses as shown in Table 2 are converted by the counters C and C, as mentioned above.

The counters C and C are of the decimal type, namely they output one pulse to the next stage every time they receives any successive pulses. The

counter C is of the binary type. Namely, for Japan and Europe the number of pulses delivered from the counter C corresponds to the unit digit of a decimal number representative of measured body weight the unit of which is the Kilogram, the number of pulses delivered from the counter C corresponds to the tenth digit of the same, and the number of pulses delivered from the counter C corresponds to the hundredth digit of the same. For U.S.A. the number of pulses delivered from the counter C corresponds to the tenth digit of a decimal number representative of measured bodyweight the unit of which is the Lb, and the number of pulses delivered from the counter C corresponds to the hundredth digit of the same. For Japan and Europe the counter C is of the binary type, as described above,

and one pulse delivered from the counter means 0.5

Kg. For U.S.A. the counter C is of the decimal type, and one pulse from the counter C means 1 Lb.

The display windows D D,, D, and D are connected to the counters C C,, C, and C, respectively. Thus, in

the display window D 5 or 0 representative of the decimal part of a number indicating body-weight (Kg) is displayed for Japan and Europe, or the unit digit of a number indicating body-weight (Lb) is displayed for U.S.A. In the display window D,, the unit digit of such number (Kg) is displayed for Japan and Europe, or the tenth digit of such number (Lb) is displayed for U.S.A. In the display window D the tenth digit of such number (Kg) is displayed for Japan and Europe, or the hundredth digit of such number (Lb) is displayed for U.S.A. In the display window 0,, the hundredth digit of such number (Kg) is displayed for Europe. Incidentally, D, indicates a display part located between the display windows D and D, and for displaying a decimal point. This display part is operated, independently of the'counters. This display part is unnecessary for U.S.A.

Table 4 shows conditions of the counters and display windows when the motor makes 199 revolutions.

As seen from Table 4, the digital display device of FIG. 8 comprising the five counters C C C C C and the display window D D D D, can be applied to weighing apparatuses for Japan, Europe and U.S.A.

In the display device of FIG. 8, it is very combersome to adjust the counter C, so as to be of the quaternary, trinary or binary type and to adjust the counter C so as to be of the binary or decimal type. In view of this, it is better to control the counters C and C by means of a decorder in such a manner that the counters C and C, are quaternary and binary respectively for Japan Kg), trinary and binary respectively for Europe (133 Kg), and binary and denary respectively for U.S.A. (300 Lbs). FIG. 9 is a block diagram of such an embodiment. DCR indicates a decorder, M and N indicate a pair of inputs of the decorder DCR. When voltages, for example H, H for Japan, L, H for Europe, and H, L for U.S.A. are applied to the input terminals M and N, the voltages are converted into control signals by the decorder DCR. The signals control the counters C, and C as shown in Table 4. The counter C is necessary only for Europe, but unnecessary for Japan and U.S.A. It will be sufficient for the counter C to be capable of counting up to a count of L.

Although the preferred embodiments have been described wherein 200 revolutions of the motor are required for one revolution of the driving plate with the servo sensor rotatably following the pointer with the controlling member as deflected proportionally to applied body-weight, every one revolution of the motor generates 4 pulses for Japan and Europe and 3 pulses for U.S.A., the counter C is quaternary for Japan, trinary for Europe and binary for U.S.A., and the counter C is binary for Japan and Europe and denary for U.S.A., these specifications should be considered being examples of this invention.

This invention is not limited to these specifications. The total number of pulses and the natures of the counters C, and C may be differently chosen so that the maximum number of pulses is 100 for Japan, 133 for Europe and 300 for U.S.A., as shown in Table 3.

As seen from the foregoing, according to this invention there is provided a digital display type weighing apparatus which comprises a pointer rotatable proportionally to applied body-weight and having a servo sensor controlling member attached to one end thereof, a driving plate driven by a motor, a servo sensor mounted on the plate and adapted to complete a short-circuit of the motor when in a position opposite to the controlling member and complete an energizing circuit of the motor when not in said position, the motor being started after the pointer and thus the controlling member begin to go ahead of the servo sensor Table 4 The The number of total Deci- ,pulses number of mal Counter Display per one pulses point Zones revolution -for 199 C, C, D, C,,C, C, D, D, D, D, D

of the revolutions motor Ja an 4 796 Quater- Binary ON Denary 9 9 5 (l Kg) nary Europe 796 Trinary Binary ON Denary Binary l 3 2 5 (133 Kg) U.S.A. 3 597 Binary Denary OFF Denary 2 9 8 (300 Lbs) not in use in response to the applied weight, completing the motor energizing circuit, and continuing to drive the driving plate until the servo sensor is brought to a position opposite to the controlling member which has been stopped at a position corresponding to the applied weight, causing the completion of the short-circuit of the motor and thus a rapid stopping of the motor, means for'converting the number of revolutions of the motor into a corresponding number of electric pulses, a counter circuit for counting the pulses, and a digital display for receiving the output of the counter circuit and providing a digital indication of the applied weight. Such structure of this invention has the following advantages: The load imposed on the motor is extremely reduced as compared with conventional drum type apparatus as mentioned before; the size of the apparatus can be smaller; the apparatus has a smaller number of parts requiring adjustments, resulting in reduction of manufacturing cost; the counter circuit can be an integrated circuit or a large scale, integrated circuit resulting in reduction of cost; the weighing characteristics (accuracy) are improved because less load is imposed on the pinion which rotates together with the pointer; to be coordinated with the improvement of weighing apparatus it is possible to design the weighing apparatus so that the least significant digit of a number displayed on the display on the display unit can indicate a fraction of 1 Kg, by increasing the number of teeth of the driving plate and the number of pulses produced per one revolution of the motor; and the apparatus has a smaller number of contacts as compared with the above mentioned conventional brush type apparatus which results in a high reliability and less need for protection against humidity and dust, and therefore is permitted to be used in a bath room.

Moreover, in the weighing apparatus of this invention, theangular distance moved by the pointer with the controlling member is proportionto applied'bodyweight is equal to that by the worm wheel with the servo sensor following the controlling member. Since this following iseffected by rotation of the motor, the number of pulses produced by the rotation of the motor corresponds proportionally to the applied body-weight. When the applied weight is removed from the weighing apparatus, the pointer with the controlling member can be automatically returned to zero position, and the worm wheel with the servo sensor is driven by the motor'to follow the controlling member thus returned. In other words, upon weighing the worm wheel with the servo sensor is automatically operated to follow the angular position of the controlling member moved according to applied weight, and upon removing of applied weight the worm wheel with the servo sensor is automatically operated to follow the zero position of the controlling member returned. Therefore, the weighing apparatus of this invention does notneed any zero point adjusting unit which has been required in conventional weighing apparatus. This .will permit a designer to design a weighing apparatus which comprises aweighing body for carrying a human body to be weighed and a digital display unit mechanically separated from, but electrically connected through leads to the weighing body, the digital display unit being adapted to be placed at the level of eyes of the human being standing on the weighing body, the weighing body being in the form of a simple platform having a novel design.

On the other hand, addition of the resetting circuit permits the counter circuit to be automatically returned to zero count. Addition of the motor time delayed starting circuit minimizes adverse influence due to vibrations of the pointer upon weighing. The added holding circuit permits the display to be maintained until a resetting pulse is generated from the resetting circuit.

Generally speaking, digital display units comprise several counters and several display parts and are very complicated and expensive. The digital display unit of this invention can be applied to weighing apparatus for Japan, Europe and USA. Therefore, it is not needed to provide differently specified digital display units for each country. Thus, digital display units of the same kind may be manufactured in mass production for the purpose of being applied to weighing apparatus for Japan, Europe and U.S.A. This leads to reduction of cost. In addition, it is possible to control the conditions of the counters C and C by means of a decorder. As will be apparent from the above, this invention also adds valuable contributions to internationalization of digital display units for weighing apparatus.

We claim:

l. A digital displaytype weighing 'apparatuscomprising: a' pointer movable proportionally to applied weight, a control member attached to said pointer, a motor having a shaft, a disk rotatable by said motor shaft upon actuation of said motor, a servo-sensor connected to said disk and oriented thereon with respect to said control member such that said servo-sensor is rotatable from and to a position opposite said control member, circuitry connecting said motor and saidservo-sensor and including means forenergizing said motor, and means for short-circuiting said motor to thereby stop the same, said control member actuating said short-circuiting means when said control member is in said position opposite said servo-sensor, said control member actuating said energizing means when said control member is moved from said position whereby, when said control member moves in response to application of weight to said apparatus said motor rotates said motor shaft and thereby said disk until said servosensor reaches again said position opposite said control member and is stopped, and contactless means cooperating with said motor shaft for converting the number of revolutions of said motor shaft into a corresponding number of electric pulses, a counter circuit for counting said pulses, and a digital display for receiving the output of said counter circuit and .for displaying the applied weight in digital form.

2. A digital display type weighing apparatus as claimed in claim 1, wherein said digital display comprises five counters C C C C and C and four display windows D D D and D,,, said counter C forming a first stage and receiving said pulses, and said counter C forming a second stage, and a decorder for adjusting said Counter C so that the total number of pulses produced for a predetermined number of revolutions of said motor shaft is converted into lOOpulses representative of the full scale, the connections of the counters with the display windows being suchthat the digit 0 or 5 of the decimal part, the unit digit and the tenth digit of a decimal number representative of the applied weight are displayed on the display windows D D and D through the counters C C and C 3. A digital display type weighing apparatus as claimed in claim 1, wherein said digital display comprises five counters C C C C and C and four display windows D D D and D said counter C forming a first stage and receiving said pulses, and said counter C forming a second stage, and a decorder for adjusting said counter C so that the total number of pulses produced for a predetermined number of revolutions of the motor is converted into 133 pulses representative of the full scale, the connections of the counters with the display windows being such that the digit 0 or 5 of the decimal part, the unit digit, the tenth digit and the hundredth digit of a decimal number representative of the applied weight is displayed on the display windows D D D and B, through the counters C C C and C respectively.

4. A digital display type weighing apparatus as claimed in claim 1, wherein said digital display comprises five counters C C C C and C and four display windows D D D and D said counter C forming a first stage and receiving said pulses, and said counter C forming a second state, a decorder for adjusting said counter C so that the total number of pulses produced for a predetermined number of revolutions of said motor shaft is converted into three hun dred pulses representative of the full scale, the connection of the counters with the display windows being such that the unit digit, the tenth digit and the hundredth digit of a decimal number representative of the applied weight is displayed on the display windows D D and D through the counters C C and C respectively.

5. A digital display type weighing apparatus as claimed in claim 1 wherein said servo sensor comprises a reed switch and said control member is a permanent magnet.

6. A digital display type weighing apparatus as claimed in claim 1 wherein said servo sensor comprises a permanent magnet and a reed switch opposed to each other, and said control member is a magnetic shielding piece.

7. A digital display type weighing apparatus as claimed in claim 1 wherein said servo sensor comprises a light-emitting diode and a phototransistor or photodiode opposed to each other, and said control member is a light shielding piece.

8. A digital display type weighing apparatus as claimed in claim 1 wherein said servo sensor comprises a Hall switch and said control member in a magnetic shielding piece.

9. A digital display type weighing apparatus as claimed in claim 1 wherein said servo sensor comprises a transformer having an air gap and a magnet, and said control member is a magnetic reluctance element.

10. A digital display type weighing apparatus as claimed in claim 1 wherein said converting means comprises a permanent magnet attached to the shaft of the motor and a reed switch opposed to the permanent magnet.

11. A digital display type weighing apparatus as claimed in claim 1 wherein said contactless means comprises a light-emitting diode and a phototransistor opposed to each other, and a disk having apertures interposed between said light emitting diode and said phototransistor and attached to the shaft of the motor.

12. A digital display type weighing apparatus as claimed in claim 1 wherein said contactless means comprises a permanent magnet attached to the shaft of the motor and a Hall switch opposed to said permanent magnet.

13. A digital display type weighing apparatus as claimed in claim 1, further comprising a delay circuit for time delayed starting of the motor.

14. A digital display type weighing apparatus as claimed in claim 1, further comprising a resetting circuit connected to said counter circuit.

15. A digital display type weighing apparatus as claimed in claim 1 wherein a holding circuit is connected to the pulse generating circuit to hold the counter circuit.

Claims

1. A digital display type weighing apparatus comprising: a pointer movable proportionally to applied weight, a control member attached to said pointer, a motor having a shaft, a disk rotatable by said motor shaft upon actuation of said motor, a servo-sensor connected to said disk and oriented thereon with respect to said control member such that said servo-sensor is rotatable from and to a position opposite said control member, circuitry connecting said motor and said servo-sensor and including means for energizing said motor, and means for shortcircuiting said motor to thereby stop the same, said control member actuating said short-circuiting means when said control member is in said position opposite said servo-sensor, said control member actuating said energizing means when said control member is moved from said position whereby, when said control member moves in response to application of weight to said apparatus said motor rotates said motor shaft and thereby said disk until said servo-sensor reaches again said position opposite said control member and is stopped, and contactless means cooperating with said motor shaft for converting the number of revolutions of said motor shaft into a corresponding number of electric pulses, a counter circuit for counting said pulses, and a digital display for receiving the output of said counter circuit and for displaying the applied weight in digital form.

2. A digital display type weighing apparatus as cLaimed in claim 1, wherein said digital display comprises five counters Co, C1, C2, C3 and C4 and four display windows D1, D2, D3 and D4, said counter Co forming a first stage and receiving said pulses, and said counter C1 forming a second stage, and a decorder for adjusting said Counter C1 so that the total number of pulses produced for a predetermined number of revolutions of said motor shaft is converted into 100 pulses representative of the full scale, the connections of the counters with the display windows being such that the digit 0 or 5 of the decimal part, the unit digit and the tenth digit of a decimal number representative of the applied weight are displayed on the display windows D1, D2 and D3 through the counters C1, C2 and C3.

3. A digital display type weighing apparatus as claimed in claim 1, wherein said digital display comprises five counters C0, C1, C2, C3 and C4 and four display windows D1 D2, D3 and D4, said counter C0 forming a first stage and receiving said pulses, and said counter C1 forming a second stage, and a decorder for adjusting said counter C1 so that the total number of pulses produced for a predetermined number of revolutions of the motor is converted into 133 pulses representative of the full scale, the connections of the counters with the display windows being such that the digit 0 or 5 of the decimal part, the unit digit, the tenth digit and the hundredth digit of a decimal number representative of the applied weight is displayed on the display windows D1, D2, D3 and D4 through the counters C1, C2, C3 and C4 respectively.

4. A digital display type weighing apparatus as claimed in claim 1, wherein said digital display comprises five counters C0, C1, C2, C3 and C4 and four display windows D1, D2, D3 and D4, said counter C0 forming a first stage and receiving said pulses, and said counter C1 forming a second state, a decorder for adjusting said counter C1 so that the total number of pulses produced for a predetermined number of revolutions of said motor shaft is converted into three hundred pulses representative of the full scale, the connection of the counters with the display windows being such that the unit digit, the tenth digit and the hundredth digit of a decimal number representative of the applied weight is displayed on the display windows D1, D2 and D3 through the counters C1, C2 and C3 respectively.