US3808791A

US3808791A - Electric clock

Info

Publication number: US3808791A
Application number: US00333875A
Authority: US
Inventors: H Hara
Original assignee: Sony Corp
Current assignee: Sony Corp
Priority date: 1972-02-26
Filing date: 1973-02-20
Publication date: 1974-05-07
Anticipated expiration: 1991-05-07
Also published as: GB1397667A; CA968167A; JPS48100170U

Abstract

An electric clock having a time display device and a driving source for intermittently driving the time display device, the driving source including a DC motor provided with a selfcontained electric power source such as a dry cell, a switch inserted between the emitter-collector electrodes of a motor driver transistor and adapted to be closed or opened by a permanent magnet which is moved toward and away from the switch in response to the rotation of the DC motor drive shaft, and a cam driven by the motor to rotate one or more drums of the time display device by a predetermined angle so as to change the time display.

Description

O United States Patent 1 [111 3,808,791 Hara 51 May 7, 1974 ELECTRIC CLOCK Primary Examiner-Richard B. Wilkinson Assistant Examiner-Edith Simmons Jackmon 75 Inventor. l-lldeo Hara Kana awa-k J 1 g en apan Attorney, Agent, or Firm-Lewis l-l. Eslinger, Esq.; Al- [73] Assignee: Sony Corporation, Tokyo, Japan i Si d b d, E

[22] Filed: Feb. 20, 1973 [21] Appl. No. 333,?15 [57] ABSTRACT Foreign Application Priority ata An electric clock having a time display device and a Feb. 26. I972 Japan ...47-23 729 driving source for intermittently driving the time display device, the driving source including a DC motor provided with a self-contained electric power source 'i 6 3 such as a dry cell, a switch inserted between the emit- [58] Fieid /4 A 23 A 23 D tercollector electrodes of a motor driver transistor 58/24 R 318/306 6 206/61 and adapted to be closed or opened by a permanent magnet which is moved toward and away from the switch in response to the rotation of the DC motor [56] References Cited drive shaft, and a cam driven by the motor to rotate UNITED STATES PATENTS one or more drumsof the time display device by a 3,568,430 3/1971 Walton...., 58/23 R predetermined angle so as to change the time display. 3,601,975 4/1969 Wuthrich 58/28 R I 3,643,419 2/1972 Motta 58/23 R 12 Claims, 5 Drawing Figures 3,134,220 5/1964 Meisner 58/28 R 3,451,210 6/1969 Helterline, Jr. et al. 58/26 R alwa'tre PATENTEMAY 11914 DIV OSC

I i- 6d 3 ELECTRIC CLOCK BACKGROUND OF THE INVENTION The present invention relates generally to an electric clock, and more particularly to a battery operated electric clock.

In some battery operated electric clocks, an electric motor is driven by the electric power from a battery such as a dry cell and the rotation of the motor is used to drive the hand of the electric clock through a gear device. In some other types of electric clocks, an electric motor is energized intermittently and at the time when the motor is energized a spring is wound up to drive the hand of the electric clock.

In such conventional electric clocks, since their electric motors are sequentially or frequently energized, an amount of electric power is consumed, which is large relative to the current capacity of the battery, with the result that the life span of the battery is shortened.

There has been also proposed an electric clock in which a pulse generated from a stabilized oscillator is supplied to a switching transistor through a frequency divider circuit and time is indicated in a digital manner in accordance with the operation of the switching transistor. In this case, however, there is the problem that if the minute or hour display is corrected by moving the hands of the electric clock only, the correction is not achieved precisely.

SUMMARY OF THE INVENTION The above and other disadvantages are overcome by an electric clock according to the present invention which comprises a self-contained power source, a semiconductor switching element, an electric motor whch is connected with the power source through the semiconductor switching element and is drivingly controlled by the semiconductor switching element, a magnet moved by the motor, and an on/off switch for controlling the semiconductor switching element' and which is responsive to the position of the magnet, whereby the motor is energized during one cycle of movement of the magnet.

Accordingly, it is an object of the present invention to provide an improved'electric clock.

It is another object of the present invention to provide an electric clock driven by a battery in which the consumption of electric power from the battery is minimized.

It is a further object of the present invention to provide a low power consumption electric clock of simple construction which can display units of time digitally.

It is a yet further object of the present invention to provide an electric clock for displaying time digitally in which time correction can be easily and precisely achieved.

The foregoing and other objectives, features, and advantages of the invention will be more readily understood upon consideration of the following detailed description of certain preferred embodiments of the invention, taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view illustrating one embodiment of an electric clock according to the invention;

FIG. 2 is a cross-sectional view taken generally along the line IIII in FIG. 1;

FIG. 3 is an enlarged front view of the reed switch used in the electric clock shown in FIGS. 1 and 2, which is used for explaining the operation of the reed switch;

FIG. 4 is a schematic diagram showing a circuit for driving the electric motor used in the electric clock of the invention; and

FIG. 5 is a block diagram showing an example of the electric clock circuit used in the present invention including a motor and time display means.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to FIGS. 1 and 2 a mechanism of an electric clock according to the present invention will be now described. In the figures, reference numeral '10 designates a generally U-shaped frame which supports a fixed shaft 11. A time display device or time display means, designated generally by reference numeral 12, is rotatably supported by the fixed shaft 11. The time display means 12 includes a first drum 13 for displaying the figure of hours, a second drum 14 for displaying the figure of 10 minute order and a third drum 15 for displaying the figure of minute order. .The drums 13 to 15 are inscribed thereon with numerals of 0 to 12, 0 to 5 and 0 to 9, respectively. The frame 10 further supports a second fixed shaft 16 on which first and second drive gears 17 and 18 are rotatablysupported.

. The first drive gear 17 has first pegs 17a, which engage with pegs 13a provided on the first drum 13 on one of its side surfaces, and second pegs 17b, which engage with pegs 14b provided on the second drum 14 on its side surface which opposes the one surface of the first drum 13. The second drive gear 18 also has first pegs 18a, which engage with pegs 14a provided on the second drum 14 on its other side surface, and second pegs 18b, which engage with pegs 15b provided on the third drum 15 on its side surface which opposes that of the second drum 14 as shown in FIG. 1.

It will be readily understood by those skilled in the art that the relationship of the

pegs

13a, 17a, 17b, 14b, 14a, 18a, 18b and 15b (in reverse order of driving engagement from left to right as viewed in FIG. 1) is such that for each complete revolution of drum l5 drum 14 is advanced one-sixth of a revolution. For each' complete revolution of drum l4, drum 13 is advanced onetwelfth of a revolution. The third drum 15 is further provided with a ratchet wheel 19 on itsright side surface in FIG. 1, which ratchet wheel 19 engages with a drum drive mechanism generally designated as 20 in FIG. 1 which will now be described in detail.

The drum drive mechanism 20 includes a DC motor 21 which is rotated one revolution per minute by a motor control circuit to be described in detail hereinafter, a magnet sensitive switch 22 such, for. example, as a reed switch, and a cam 23. The DC motor 21 is mounted on a sub-frame 26 which is attached to the U- shaped frame 10 by means of

rods

24 and 25. The motor 21 has a worm gear 27 on its rotary shaft. A first rotatable shaft 30 is rotatably supported between the frame 10 and the subframe 26. The shaft 30 has mounted thereon a first gear wheel 28 engaged with the worm gear 27 and a second gear wheel 29. A second rotatable shaft 32, which has mounted thereon a third gear wheel 31 engaged with the second gear wheel 29,

is also rotatably supported between the frame and the sub-frame 26 so that one end projects through one leg of the frame 10. The cam 23 is attached to the second rotatable shaft 32 at its projecting end and has a curved cam surface with a peak 23a on one end, as shown in FIGS. 1 and 2.

A swing lever 35 is rotatably supported on the second fixed shaft 16 and is biased to rotate in the counterclockwise direction as viewed in FIG. 2 by means of a coil spring which is not shown. The swing lever 35 has a pin 36 which contacts with the curved cam surface of the cam 23 and a pawl 37 which is pivotably mounted on the lever 35 and which engages with the ratchet wheel 19. The pawl 37 is biased to the clockwise direction by means of a coil spring (though not shown) in FIG. 2, while the ratchet wheel 19 is prevented from reverse rotation by a leaf spring (not shown).

As is shown in FIGS. 2 and 3 a fixed shaft 40, supported by the

frames

10 and 26, has a lever 39 pivoted thereto at one of its ends. The lever 39 has a magnet 38 attached at its other end which may oppose the reed switch 22. The lever 39 is biased to the counterclockwise direction by a coil spring 41 wound on the shaft 40 (refer to FIGS. 1 and 2) and has mounted thereon an extension plate 43 which may engage with a cam plate 42 fixed on the second rotatable shaft 32 as shown in FIG. 3.

Referringnow to FIG. 4, an example of the motor control circuits for driving the DC motor 21 is illustrated. The DC motor 21 is connected in'series with a semiconductor switching element 50 (which is a transistor in the illustrated embodiment) and a battery 51. In this embodiment, in particular, the switch 22 is connected between the battery 51 and a base electrode b of the transistor 50. An emitter electrode e of the transistor 50 is connected in series through the battery 51 and the DC motor 21 to its collector electrode 0.

With such an arrangement, if the magnet 38 is in a position spaced apart from the switch 22, as shown in FIGS. 3 and 4 by the solid line, the switch 22 is kept in its OFF-state. On the other hand, if the magnet 38 closely opposes the switch 22, as shown in FIGS. 3 and 4 by the dashed lines, the switch 22 is closed in its ON- state and the switching element 50 is biased into its conductive state. Power from the battery 51 is then supplied to rotate the motor 21. In the normal state, the magnet 38 is apart from the switch 22 and the DC motor 21 stops its rotation.

The base electrode b of the transistor 50 is supplied with a pulse at a predetermined time, for example once a minute, from a clock circuit which includes a quartz oscillator55 for generating a signal with a frequency, for example, of 32,768 KI-Iz and first and

second frequency dividers

56 and 57. In detail, the divider 56 converts the signal with frequency of 32.768 KI-iz into a signal with a frequency of 1 Hz, while the divider 57 is a counter with a scale of 60 and a reset terminal 57a. Accordingly, from the divider 57 there is derived one pulse per 1 minute or 60 seconds. The reset terminal 57a of the divider 57 is supplied with a pulse from an external source not shown)in association with a zero reset pin (not shown) of the third drum to clear the contents of the counter 57 to be zero. This operation will be described latter on.

In operation, when one pulse is applied to the base electrode b of the transistor 50 from the divider 57 in the clock circuit, the transistor 50 is made ON to energize the DC motor 21. The rotation of the DC motor 21 is transmitted to the second rotatable shaft 32 through the worm gear 27, the gear 28, the shaft 30, and the

gears

29 and 31, with the result that the cam 23 and the cam plate 42 fixed to the second rotatable shaft 32 are rotated. When the cam plate 42 is rotated by a predetermined angle, the peak portion 42a of the cam plate 42 disengages from the extension plate 43 of the lever 39, thereby allowing the magnet 38 to approach the reed switch 22 with the result that the reed switch 22 is turned ON to hold the transistor in its ON-state even if no pulse is applied to its base electrode b from the divider 57. The DC motor 21 is thereby continuously rotated until the peak portion 23a of the cam 23 engages the pin 36 to swing. the lever 35 in the clockwise direction as viewed in FIG. 2. The movement of the lever 35 and the pawl 37 against the ratchet wheel 19 causes the third drum 15 to be rotated to the clockwise direction as viewed in FIG. 2 by one tooth of the ratchet wheel 19 to display that the time has been changed.

When the peak portion 42a of the cam plate 42 again engages with the extension plate 43 of the lever 39 due to the rotation of the DC motor 21, the lever 39 rotates to the clockwise direction as viewed in FIG. 3 against the spring force of the spring 41. As a result, the magnet 38 is again spaced apart from the reed switch 22 to put the latter in its OFF-state. Hence, the transistor 50 is turned OFF to stop the rotation of the motor 21. As mentioned above, the third drum 1-5 for displaying the figure of minutes is intermittently driven by 1/10 rotation per one minute by the operation of the pawl 37 with the ratchet wheel 19. I

The pulse width of the pulse applied to the transistor 50 may be a time period within which the reed switch 22 is made ON, for example, abour I second. The transistor 50 is kept in its ON-state by the switch 22 after it is turned ON by the pulse and the DC motor 21 is kept rotating during the time period within which the magnet 38 approaches the switch 22. Although the DC motor 21 is required to be rotated during this time period so as to advance the time display byone minute, it is enough that the motor 21 is rotated for only a short time period, for example, about 3 to 6 seconds every 1 minute. Accordingly, it will be easily understood that the electric clock of the present inventio'nconsumes a very small amount of electric power.

means for resetting the contents of the divider or thecounter 57 to be 0 in association with means for resetting the third drum 15 to be 0. By way of example, the means for making the third drum 15 to be 0" consists of a cam provided on one side of the ratchet wheel 19 and a pin 62 supported in the frame 10. The pin 62 is biased away from the cam 60 by a coil spring 63, but when the pin 62 is manually pushed against the coil spring 63, the tip end of the pin 62 contacts the cam 60 at a straight portion of its side surface to forcibly reset the third drum 15 to be 0. Such reset means are well known in the art and another type of such means could be employed without derogating from the invention. When the pin 62 is pushed, the reset signal is applied to the reset terminal 57a of the divider or counter 57 to reset the contents thereof.

With such an arrangement, the time display is reset and at the same time the counter 57 is also reset to carry out the time display correction with a time period on the order of a second. It is assumed that when the counter 57 counts, for example, 35, the drum is reset to be 0. If no provision were made for simultaneously resetting the counter 57 at the same time, then since the counter 57 may start to count the pulses from the divider 57 from35, the motor 21 might be driven when the counter 57 counts 60" to display 1 on the drum 15. In other words, this would result in the error of 25 seconds in the time display. In the invention, however, since the counter 57 is reset at the same time as the drum 15 is reset to 0, such an error mentioned just above is avoided.

In the foregoing embodiment of the present invention, the third drum 15 is only reset, but in the other embodiments the first and second drums l3 and 14 are reset at the same time to be 0, respectively. In such embodiments, the first divider 56 may be reset simultaneously.

Further, in other embodiments it is possible to employ a hole element in place of the reed switch 22. In general, various switching devices well known in the art can be used instead of the magnet and reed switch assembly.

While the above embodiment has been described with reference-to a time display having only hours, tens of minutes and minutes represented, it should be understood that in still other embodiments the time dis-. play may include lesser or greater divisions of time such as days and months, by way of example only.

The terms and expressions which have been employed here are used as terms of description and not of limitation, and there is no intention in the use of such terms and expressions, of excluding equivalents of the features shown and described, or portions thereof, it being recognized that various modifications are possible within the scope of the invention claimed.

What is claimed is:

1. An improved electric clock of the type having a motor with a drive shaft, a self-contained electric power source and time display means, wherein the improvement comprises:

a. semiconductor switching means connected to the power source and the motor for intermittently energizing the motor at periodic intervals of time, the semiconductor switching means having a control electrode supplied with pulses,

b. a circuit including at least an on/off reed switch connected to said control electrode for controlling the semiconductor switching means,

c. means driven by the motor for closing and opening the on/off reed switch in response to the rotation of the motor drive shaft whereby the semiconductor switching means continues to energize the motor when the on/off reed switch is closed, and

d. means for driving the time display means so as to advance the time display means by one unit of time in response to the rotation of the motor drive shaft.

2. An electric clock as recited in claim 1 wherein the means for driving the time display means include reduction gear means and a cam which is rotated with the rotation of the motor drive shaft through the reduction gear means and a lever engaged with the cam and having a pawl, a ratchet wheel mounted on the time display means and rotated with the rotation of the cam through the pawl of the lever.

3. An electric clock as recited in claim 2 wherein the time display means include a plurality of drums arranged in a predetermined sequence, each drum having numerals for time display, and gear means, each provided between adjacent ones of the drums for intermittently transmitting the rotation from one drum to the next adjacent drum, in sequence, the ratchet wheel being provided on one of the end drums.

4. An electric clock as recited in claim 2 wherein the on/off switch is magnetically sensitive, the means for opening and closing the on/off switch includes a magnet and means for supporting the magnet for movement toward and away from the on/off switch to open and close it in response to rotation of the motor drive shaft, means for maintaining the magnet near the on/off switch for continuously closing the same during the rotation of the motor drive shaft, and wherein the means for driving the time display means are mechanically connected to the means for maintaining the magnet near the on/off switch.

5. An electric clock as recited in claim 4 wherein the means for maintaining said magnet near the on/off switch include a cam.

6. An electric clockas recited in claim 1 wherein the semiconductor switching means include a transistor, and the on/off reed switch and the power source being connected in series between the base-emitter electrodes of the transistor, and the power source and the motor being connected in series between the emittercollector electrodes of the transistor.

7. An electric clock as recited in claim 1. further comprising a stabilized oscillator and frequency dividing means for dividing the frequency of a signal generated by the oscillator, the output from the frequency dividing means being applied to the semiconductor switching means so that the time display means are driven by the motor which is intermittently energized.

8. An electric clock as recited in claim 7 in which the time display means include a moving body which has thereon the numerals of 0" to 9" for displaying at least the figure of minutes, the moving body having zero reset means.

9. An electric clock as recited in claim 8 in which the zero reset means are coupled to means for zeroresetting the frequency dividing means. 2

10. An electric clock as recited in claim 9 in which the frequency dividing means include a divider for frequency-converting the signal from the oscillator to that with the frequency of 1 Hz and a counter of scale of 60 for counting the signal of 1 Hz to 60 and then producing one pulse which is fed to the control electrode of the semiconductor switching means, the counter of scale of 60 having a terminal which is ganged with the zero reset means of the time display means to zeroreset the counter contents to be zero.

11. An electric clock of the type having a motor, an electric power source, time display means and an oscillator, comprising:

a. switching means for intermittently supplying power to said motor from said electric power source;

b. means for coupling said switching means to said oscillator to actuate said switching means in response to a pulse supplied by said oscillator such that rotation of said motor is initiated thereby;

c. means for maintaining the actuation of said switching means for a predetermined duration of rotation 12. An electric clock as recited in claim 11 wherein the maintaining means includes a magnetically operated reed switch; a movable cam driven in response to the rotation of said motor; and a magnet selectively positionable into operating relation with said reed switch in accordance with the movement of said cam.

Claims

1. An improved electric clock of the type having a motor with a drive shaft, a self-contained electric power source and time display means, wherein the improvement comprises: a. semiconductor switching means connected to the power source and the motor for intermittently energizing the motor at periodic intervals of time, the semiconductor switching means having a control electrode supplied with pulses, b. a circuit including at least an on/off reed switch connected to said control electrode for controlling the semiconductor switching means, c. means driven by the motor for closing and opening the on/off reed switch in response to the rotation of the motor drive shaft whereby the semiconductor switching means continues to energize the motor when the on/off reed switch is closed, and d. means for driving the time display means so as to advance the time display means by one unit of time in response to the rotation of the motor drive shaft.

6. An electric clock as recited in claim 1 wherein the semiconductor switching means include a transistor, and the on/off reed switch and the power source being connected in series between the base-emitter electrodes of the transistor, and the power source and the motor being connected in series between the emitter-collector electrodes of the transistor.

7. An electric clock as recited in claim 1 further comprising a stabilized oscillator and frequency dividing means for dividing the frequency of a signal generated by the oscillator, the output from the frequency dividing means being applied to the semiconductor switching means so that the time display means are driven by the motor which is intermittently energized.

8. An electric clock as recited in claim 7 in which the time display means include a moving body which has thereon the numerals of ''''0'''' to ''''9'''' for displaying at least the figure of minutes, the moving body having zero reset means.

9. An electric clock as recited in claim 8 in which the zero reset means are coupled to means for zero-resetting the frequency dividing means.

10. An electric clock as recited in claim 9 in which the frequency dividing means include a divider for frequency-converting the signal from the oscillator to that with the frequency of 1 Hz and a counter of scale of 60 for counting the signal of 1 Hz to 60 and then producing one pulse which is fed to the control electrode of the semiconductor switching means, the counter of scale of 60 having a terminal which is ganged with the zero reset means of the time display means to zero-reset the counter contents to be zero.

11. An electric clock of the type having a motor, an electric power source, time display means and an oscillator, comprising: a. switching means for intermittently supplying power to said motor from said electric power source; b. means for coupling said switching means to said oscillator to actuate said switching means in response to a pulse supplied by said oscillator such that rotation of said motor is initiated thereby; c. means for maintaining the actuation of said switching means for a predetermined duration of rotation of said motor, said duration of rotation being less than on-half of a period of unit time; and d. means for driving said time display means to advance the indication of time displayed by said time display means by one unit of time in response to the rotation of said motor for each rotation duration.

12. An electric clock as recited in claim 11 wherein the maintaining means includes a magnetically operated reed switch; a movable cam driven in response to the rotation of said motor; and a magnet selectively positionable into operating relation with said reed switch in accordance with the movement of said cam.