Abstract:
A time detecting switch for an alarm clock comprises phase detecting type slide switches between rotatable coaxially mounted pairs of time wheels and detecting wheels which are rotated to the phases corresponding to an alarm signalling time according to an alarm signalling time setting. One of the pair of the two kinds of wheels comprises a disk of electrically insulating material having a hole therethrough, and an electrically conductive switch plate mounted on one face of the disk has an electric contacting portion which extends through the hole in the disk and bent to form a contacting face in the same plane with the other face of the disk.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a time detecting switch device for an alarm clock to actuate an electric alarm signaling device at a preset alarm signaling time. 
     The essential mechanism of the conventional detecting device for an alarm clock is a drop-in type mechanism constituted of holes and projections provided for time wheels and corresponding detecting wheels, respectively. This mechanism has a disadvantage that, in setting the alarm signaling time or in adjusting time indication, the corresponding setting knob or adjusting knob can be rotated in only one direction because the wall of the hole and the side face of the projection are shaped vertically straight with each other so as to make the projection drop in the hole instantaneously to attain accurate alarm signaling time detection. A further disadvantage of this conventional mechanism is that the electromechanical transducer is undesirably loaded when the projection escapes out of the hole along the inclined wall of the hole with rotation of the wheels. 
     SUMMARY OF THE INVENTION 
     In order to overcome those disadvantages, the detecting device according to this invention is provided with a phase detecting type slide contact switch which is more simple in fabrication and less costly. 
     The object of the invention is attained by providing a phase detecting type slide switch arranged between a detecting wheel and a time wheel of an alarm clock, either one of the wheels is made of electric insulating material and provided with an electric conductive switch plate having an elongation extending through a hole on the face of the wheel as far as to the plane of the bottom face of the wheel forming a contact point. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a sectional view of the first embodiment of the invention. 
     FIGS. 2 and 3 are partial plan views of FIG. 1. 
     FIG. 4 is a partial plane view of FIG. 3. 
     FIG. 5 is a sectional view of the second embodiment of the invention. 
     FIG. 6 is a fragmentary perspective view of FIG. 5. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIGS. 1 to 4 inclusive, a explanation will be made of the first embodiment. 
     A case (1) made of plastics has a projection (1a) at its left end and holes to rotatably guide an hour wheel (12), an alarm signaling time setting wheel (18) and a time indication adjusting wheel (14). 
     A middle frame (2) also is made of plastics having bosses and holes rotatably guiding an intermediate spindle (7), a minute wheel (9), a time indication adjusting wheel (14) and an intermediate hour wheel (11). 
     A cover (3) also is made of plastics having bosses and holes for rotatably guiding a shaft (6) of a second wheel, the intermediate spindle (7), the time indication adjusting wheel (14), an alarm signaling time setting wheel (18), a minute alarm signaling time indicating wheel (20) and an hour alarm signaling time indicating wheel (21). 
     A screw (4) fastens the cover (3) to the case (1). 
     The following explanation is concerned with a gear train for the time indicating mechanism. 
     A pinion (5a) and the second wheel (5) formed in a body are fixed to the spindle (6) extending through the tubular boss (9b) of the minute wheel (9). The second hand (33) is fixed to the spindle (9) at its projecting end. The second wheel (5) is driven by a motor, for instance a step motor, not shown. 
     The intermediate spindle (7), a pinion (7a), a first flange (7b), a groove (7c) and a second flange (7d) are made of plastics in a body. 
     An intermediate wheel (8) engaging with the pinion (5a) is rotatably fitted on the first flange (7b) and pressed against the first flange (7b) by a leaf spring (32) retained by the groove (7c) so that the intermediate wheel (8) and the spindle (7) are frictionally coupled. The minute wheel (9) engaging with the pinion (7a) is formed with the pinion (9a) in one body and the tubular boss (9b) extends through the hour wheel (12) and provided with the minute hand (10) at its end. 
     The intermediate hour wheel (11) engaging with the pinion (9a) and the pinion (11a) are formed in a body. The hour wheel (12) engaging with the pinion (11a) and its tubular boss (12a) are made of plastics in a body. The hour hand (13) is fixed to the end of the tubular boss (12a). The time indication adjusting wheel (14) also is engaged with the intermediate hour wheel (11). The shaft (14a) of the time indication adjusting wheel (14) projects through the cover (3) and is fixedly provided with a knob (15) at the end. 
     The following explanation is concerned with a gear train for the alarm signaling mechanism. 
     A minute detecting wheel (16) made of electric conductive material is rotatably fitted on the tubular boss (9b) between the minute wheel (9) and the hour wheel (12). An hour wheel (17) made of electric conductive material is rotatably fitted on the tubular boss (12a). 
     An alarm signaling time setting wheel (18) of a compound wheel made of plastics is constituted in a body of a first wheel (18a) engaging with the minute detecting wheel (16), a second wheel (18b) engaging with the hour detecting wheel (17) and a third wheel (18c). 
     A knob (19) is fixed to the alarm signaling time setting wheel (18) at an end. A minute alarm signaling time indicating wheel (20) engaging with the third wheel (18c) is provided with place advancing teeth for intermittently driving an hour alarm signaling time indicating wheel (21), a click-stop wheel (20b) engaging with a click-stop spring (29) fixed to the case (1) and minute marks (20c) such as 0, 5, . . . 55, on its front surface. The hour alarm signaling time indicating wheel (21) is provided with a gear engaging with the place advancing teeth of the minute signaling time indicating wheel (20) and hour marks (21b), such as 1, 2, . . . 12, on its front surface. 
     The alarm signaling mechanism is set at an optional time by turning the knob (19) and observing the time indication by the alarm signaling time marks (20c) and (21b). 
     The following explanation is concerned with a switching mechanism for detecting the alarm signaling time. 
     One terminal of a buzzer (B) is connected to the negative terminal of a battery (E) through a medium of a manual switch (SW) operated by an alarm signaling setting knob (23) while the other terminal is connected to a first stationary contact plate (22). The hour detecting wheel (17) has on its bottom face three first projections (17a) disposed on the same circle at equal angular intervals and on its upper face three second projections (17b) disposed on different circles at equal angular intervals as shown in FIG. 3 by dotted lines. 
     The hour detecting wheel (17) and the first stationary contact plate (22) are always electrically connected by the contact of the first projection (17a) with the stationary contact plate (22). 
     An hour switch plate (24) fixed on the hour wheel (12) has raised slide contact pieces (24a) and slide contact pieces (24b) extending downwardly penetrating the hour wheel (12) as shown in FIG. 4 and disposed on different circles at equal angular intervals as shown in FIG. 3. The contact faces of the slide contact pieces (24b) are almost in the plane of bottom face of the hour wheel (12). Normally, the hour wheel (12) and the hour detecting wheel (17) are electrically disconnected as the second projections (17b) of the hour detecting wheel (17) are in contact with bottom face of the hour wheel (12) and are electrically connected once every twelve hours when the second projections (17b) have come in contact with the corresponding slide contact pieces (24b). 
     An additional explanation will be made of the construction of the switch. 
     Generally, either of the contact pieces, integral parts of a slide switch, is of elastic type in order to ensure contact, however, the slide switch according to the invention has the possibility of failing in positive contact as both contact pieces, the detecting wheel (17) and the slide contact pieces (24b) of the hour switch plate, are rigid. 
     In this embodiment, this problem is solved by providing three slide contact pieces (24b) and three corresponding second projections (17b) which are arranged to come in contact with each other almost at the same time. The provision of three second projections (17b) also has the advantage to keep the hour wheel (12) in a horizontal position. The hour switch plate (24) and the minute detecting wheel (16) are always in electric contact as the slide contact pieces (24a) are in sliding contact with the bottom face of the minute detecting wheel (16). 
     An insulating plate (25) is made of electric insulating material. 
     A sectoral switch plate (26) made of electric conductive material is shaped as shown in FIG. 2. The insulating plate (25) and the sectoral switch plate (26) are disposed on the minute detecting wheel (16) in the order of the insulating plate (25) and the sectoral switch (26) and fastened by means of caulking so that the minute detecting wheel (16) and the sectoral switch plate (26) are electrically connected. 
     A minute switch plate (27) having a downwardly extending slide contact piece (27a) is fixed on the minute wheel (9). The slide contact piece (27a) slide on the insulating plate (25) coming in electric contact with the sectoral switch plate (26) once every hour. 
     On the middle frame (2) there is fixed a second stationary contact plate (28), one elongation of which is in sliding contact with the upper face of the minute wheel (9) and the other elongation is connected to the positive terminal of the battery (E) so that the minute wheel (9) is always electrically connected with the positive terminal of the battery (E). 
     The following explanation is concerned with the performance of the switching mechanism. 
     The alarm signaling mechanism is set to generate an alarm signal at an optional time by turning the knob (19) and observing the time indication by the alarm signaling time marks (20c) and (21b). The phases of the minute detecting wheel (16) and the hour detecting wheel (17), that is the phases of the sectoral switch plate (26) and the second projection (17b) of the hour detecting wheel (17), are determined according as the setting of the alarm signaling mechanism. The manual switch (SW) is turned on by the alarm signaling setting knob (23). At this moment the buzzer will not be actuated as electric circuit, the sectoral switch plate (26)--the minute switch plate (27) or the hour detecting wheel (17)--the hour switch plate (24), is not closed. 
     As time passes, the minute switch plate (27) and the hour wheel (12) rotate once every hour and once every twelve hours, respectively. 
     The minute detecting wheel (16) and the hour detecting wheel (17) are urged to rotate by frictional force introduced by rotation of the minute wheel (16) and the hour wheel (17), respectively, however, both of them will be retained at the preset phases as they are restrained by the minute alarm signaling time indicating wheel (20), which is restrained by the click-stop spring (29), through engagement with the third wheel (18c) and the second wheel (18b), respectively. 
     Although the contact 27a of minute switch plate (27) comes in electric contact with the sectoral switch plate (26) once every hour, the buzzer (B) will not be actuated as the hour switch plate (24) has not come in electric contact with the hour detecting wheel (17) yet. As time passes, the phases of the slide contact pieces (24b) of the hour switch plate are synchronized with the phases of corresponding second projections (17b) of the hour detecting wheel for the first place and the hour switch plate 24 and the hour detecting wheel 17 are electrically connected. 
     The slide contact pieces (24b) are so designed as to maintain the contact between the slide contact pieces (24b) and the second projections (17b) for twenty to forty minutes during which the slide contact piece (27a) of the minute switch comes in electric contact with the sectoral switch plate (26) so that the electric circuit, the first stationary contact plate (22)--the hour detecting wheel (17)--the hour switch plate (24)--the minute detecting wheel (16)--the sectoral switch plate (26)--the minute switch plate (27)--the second stationary contact plate (28), is closed throughout to actuate the buzzer (B). 
     The buzzing can be stopped at any time by turning off the manual switch (SW). The buzzing is cut off automatically even when the manual switch (SW) is left turned on after a period of time corresponding to the length of the sectoral part of the sectoral switch plate (26). 
     Therefore, the period of buzzing time can be optionally determined by properly designing the length of the sectoral part of the sectoral switch plate (26). 
     The following explanation is concerned with time indication adjustment. 
     Rotation of the time indication adjusting wheel (14) by means of the knob (15) is transmitted to the minute wheel (9) and the hour wheel (12) through the intermediate hour wheel (11). Although the minute detecting wheel (16) and the hour detecting wheel (17) are urged to turn by frictional force provided by the minute wheel (9) and the hour wheel (12), they are restrained by the minute alarm signaling time indicating wheel (20) which is restrained by the click-stop spring (29). Rotation of the time indication adjusting wheel (14) is also transmitted to the intermediate spindle (7) through the minute wheel (9), however, the intermediate wheel (8) frictionally coupled with the intermediate spindle (7) by pressure provided by the leaf spring (32) is restrained, independently of rotation of the intermediate spindle (7) by the motor torque introduced through the second wheel (5) because the torque provided by the motor is greater than the frictional force between the intermediate spindle (7) and the intermediate wheel (8). Thus time indication can be adjusted by turning the knob (15) in either direction. 
     Referring now to FIG. 5 and FIG. 6, an explanation will be made of the second embodiment of the invention. 
     A cover (103) and a printed circuit board (130) are fastened to a projection (102a) disposed at the left end of a middle frame (102) by means of screws (104). A gear train for the time indicating mechanism is constituted, similarly to that of the first embodiment, of a second wheel (105), an intermediate spindle comprising frictional coupling means and an intermediate wheel, not shown, a minute wheel (109), an intermediate hour wheel (111) and an hour wheel (112). 
     The following explanation is concerned with the gear train for the alarm signaling mechanism. 
     A second minute wheel (141) made of plastics rotates at a rotating rate equivalent to that of the minute wheel (109). A minute detecting wheel (125) made of electric conductive material is disposed between the second minute wheel (141) and the printed circuit board (130) and provided with three second projections (125b) on the upper face on different circles at equal angular intervals and three first projections (125a) on the bottom face on a circle at equal angular intervals similarly to the first embodiment. 
     An hour detecting wheel (117) is disposed between an hour wheel (112) and the printed circuit board (130) and fixedly provided with an index (132) at the end of its tubular boss (117c). An alarm signaling time setting wheel (118) comprises a first wheel (118a) and a second wheel (118b) and fixedly provided with an alarm signaling time setting knob (119) at an end. The first wheel (118a) is engaged with an idle wheel (134). The second wheel (118b) is engaged with the hour detecting wheel (117). The alarm signaling time setting wheel (118) is controlled by a fixed frictional force provided by a friction piece (133) fixed to the middle frame at one end and pressed against the upper face of the first wheel (118a). 
     The following explanation is concerned with the alarm signaling time detecting switch. 
     The printed circuit board (130) comprises a first pattern (130a) connected with one terminal of a buzzer (B) and a second pattern (130b) connected with the positive terminal of a battery (E). 
     Hour detecting wheel (117) made of electric conductive material is provided on its upper and bottom face three first projections (117b) and three second projections (117a), respectively, as in the first embodiment. The hour detecting wheel (117) and the first pattern (130a) are always electrically connected as the first projections (117a) are always in sliding contact with the first pattern (130a). 
     The hour wheel made of plastics is fixedly provided with an hour switch plate (124) having a downwardly extending contact piece (124b) as in the first embodiment. The minute detecting wheel (125) and the second pattern (130b) are always electrically connected as the second projections (125a) are always in sliding contact with the second pattern (130b). Fixed on the second minute wheel (141) made of plastics is a minute switch plate (127) having downward projections (127a) arranged on three different circles and come in electric contact with corresponding second projection (125b) of the minute detecting wheel (125) once every hour. 
     The hour switch plate (124) and the minute switch plate (127) are always electrically connected as a first elongation (128a) and a second elongation (128b) of a stationary contact plate (128) are always in sliding contact with the upper faces of the hour switch plate (124) and the minute switch plate (127), respectively. 
     The following explanation is concerned with performance of the alarm signaling mechanism. 
     In this embodiment, the alarm signaling mechanism is set to go off at an optional time by turning the alarm signaling time setting knob (119) observing indication of the index (132), while the minute detecting wheel (125) and the hour detecting wheel (117) are set at the phases corresponding to the alarm signaling time by the rotation of the alarm signaling time setting knob (119) transmitted to those detecting wheels through the first wheel (118a) and the second wheel (118b) on the alarm signaling time setting spindle (118) and the idle wheel (134). Alarm signaling mechanism setting is completed by turning on the manual switch (SW). 
     Although the second projections (125b) of the minute detecting wheel and the downward projections (127a) of the minute switch plate come in electric contact once every hour, the buzzer will not be actuated until the hour detecting wheel (117) and the hour switch plate will have been electrically connected synchronously. As time passes, the phases of the second projections (117b) and the projections (124b) of the hour switch plate are synchronized in the first place so that the hour detecting wheel and the hour switch plate are electrically connected. While the electrical connection between the hour detecting wheel and the hour switch plate is maintained, the phases of the second projections (125b) of the minute detecting wheel and the projections (127a) of the minute switch plate come in synchronism so that the minute detecting wheel and the minute switch plate are electrically connected, thus when the electric circuit, the first pattern (130a)--the hour detecting wheel (117)--the hour switch plate (124)--the stationary contact plate (118)--the minute switch plate (127)--the minute detecting wheel (125)--the second pattern (130b), is closed all through, the buzzer (B) is actuated. 
     An explanation of the other performances will be omitted as they are quite identical with those of the first embodiment. 
     In the preferred embodiments described hereinbefore, the alarm signaling time is detected both at minute and hour place, however, in modifications, the function of the second minute wheel of the second embodiment may be substituted by the intermediate hour wheel having a switching function or the alarm signaling time may be detected only at the hour place omitting the detection at the minute place. 
     According to the invention, undesirable influence of alarm signaling time setting operation to cause the prefixed phases of the index and the time hands to deviate is eliminated by introduction of the slide contact switches to the detecting mechanism and at the same time, the alarm signal actuating circuit is simply constituted as the wheels of the gear trains are employed as constituents of the electric circuit.