Abstract:
A rotary time-indicating plate-type digital display device comprises a rotary minute drum carrying a set of minute-indicating plates and a rotary hour drum carrying a set of hour-indicating plates. A drive system effects continuous rotation of the minute drum to individually turn over successive minute-indicating plates to display the time in minutes and effects intermittent rotation of the hour drum to individually turn over successive hour-indicating plates to display the time in hours. A lower system coacts with the minute and hour drums to effect synchronous turning over of the minute-indicating plate which indicates the 59th minute and each successive hour-indicating plate. An adjusting mechanism is disposed adjacent the minute drum for enabling adjustment of both the minute and hour drums to set the time displayed by the indicating plates.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a rotary indicating plate type digital display device. 
     In rotary indicating plate type digital display devices of a clock, etc., the driving system for a minute drum and an hour drum has heretofore included two types. One of them continuously drives both the minute drum and the hour drum, while the other intermittently drives both the minute drum and the hour drum. With the former type, a shear arises in the indicated characters of the hour and the minute, and hence, the number of hour indicating plates need be made large. Besides, the independent corrections of the hour and the minute are difficult. Further, in order that the change of the minute indication from &#34;59&#34; to &#34;00&#34; and the change of the hour indication may be carried out at the same time, specific minute indicating plates, for example, minute indicating plates for indicating &#34;45&#34; - &#34;59&#34; are provided with projecting pieces, and an engaging spring which shifts to the front of the hour indicating plate in interlocking relationship with the projecting piece is provided between the hour drum and the minute drum. In consequence, the spacing between the hour drum and the minute drum becomes large. Moreover, when a calender mechanism is provided, the date or the day of the week does not change exactly at 12.00 p.m., but errors of several minutes are involved. On the other hand, the latter type requires a driving torque which is greater than in the former. In addition, a comparatively large noise is generated every minute by the intermittent drive and such noise is offensive to the ear. 
     SUMMARY OF THE INVENTION 
     According to this invention, there is provided a rotary indicating plate type digital display device comprising a rotary indicating mechanism for the minute indication and which is continuously driven, a cam which interlocks with the minute drive mechanism, and a rotary indicating mechanism for the hour indication which is intermittently driven by the cam. 
     An object of this invention is to effect the change of the hour indication at the same time that the minute indication changes from &#34;59&#34; to &#34;00.&#34; 
     Another object of this invention is to realize a drive system which requires only a comparatively small driving torque. 
     Still another object of this invention is to diminish the shear in indicated characters by intermittently driving a drum for the hour indication. 
     Yet another object of this invention is to make it possible to independently correct the minute indication and the hour indication. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The above and other objects and features of this invention will become apparent from the following description and the statement of the appended claims when considered with reference to the accompanying drawing in which: 
     FIG. 1 is a front view, partially in section, showing an embodiment of this invention, 
     FIG. 2 is a sectional view taken along line II--II in FIG. 1, 
     FIG. 3 is a sectional view taken along line III--III in FIG. 1, 
     FIG. 4 is a front view of an indicating plate, and 
     FIGS. 5 to 12 are front views of various minute-indicating plates with indicating characters printed thereon. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1, a time indicating portion of the device has sixty minute-indicating plates 1, . . . , and twenty-four hour-indicating plates 2, . . . . which lie on the left of the minute indicating plates. On the left of the time indicating portion, thirty-one date-indicating plates 3, . . . . are disposed above, while seven day-of-the-week indicating plates 4, . . . . are disposed below. 
     First, a driving mechanism A for the minute-indicating plates 1, . . . will be explained. The rotation of a motor (not shown) is transmitted to a pinion 5. 
     The pinion 5 meshes with a gear 6. A tooth 6a is formed on the right side surface of the gear 6 as shown in FIG. 2, and it meshes with a pawl 7. A seat 8a is rotatably supported on an arbor 8, as seen in FIG. 1, and at one end of the seat 8a, the gear 6 is rotatably supported, and the pawl 7 is secured whereas at the other end of the seat 8a is mounted an intermediate gear 9 which meshes with a minute driving gear 10. The minute driving gear 10 is formed integrally with a minute drum 11. The minute drum 11 is rotatably supported on a main shaft 12, and has the sixty minute-indicating plates 1 rockably or pivotably mounted thereon at equal intervals along its outer periphery. The minute-indication is made by two minute indicating plates. Each time one elapses, the upper indicating plate turns over and falls, and the next minute increment of time is indicated. A cam 13 is secured to the minute driving gear 10. The cam 13 is formed with a crest 13a and a trough 13b. 
     Description will now be made of a driving mechanism B for the hour-indicating plates 2, . . . An hour drum 14 rotates together with the main shaft 12 through a pin 15 which is planted on the main shaft 12. Along the outer periphery of the hour drum 14, the twenty-four hour-indicating plates 2 are rockably or pivotably mounted at equal intervals. Referring to FIGS. 1 and 2, an hour driving lever 16 is rockably supported on an arbor 17. It is formed at one end with a sliding part 16a which the cam 13 follows, and at the other end with a hook part 16b which catches the minute-indicating plate 1. An hour driving pawl 18 for the hour driving lever 16 is rockably mounted by a pin 19. A coiled spring 20 is retained so as to bestow a turning or biasing force which tends to turn the hour driving lever 16 clockwise in FIG. 2 about the arbor 17. By the turning of the hour driving lever 16 in the clockwise direction in FIG. 2, a ratchet wheel 21 secured to the main shaft 12 has one detent fed by the hour driving pawl 18. 
     A corresponding mechanism will now be described. A minute correcting gear 24 is secured at the fore end of an arbor 23 of a minute correcting knob 22, and it meshes with the minute driving gear 10. An hour correcting knob 25 is secured to a pipe or tubular member 26 which is free to rotate relative to the arbor 23, and to which an hour correcting lever 27 is secured. The hour correcting lever 27 has a U-shaped elastic part 27a, which is formed at its fore end with a driving pawl 27b engageable with the ratchet wheel 21. By securing a pin 28 to the pawl part and snugly fitting the pin into a guide hole 29a provided in a supporting plate 29, the ratchet wheel 21 is so controlled as to prevent two or more detents from being fed. At the end of the hour correcting lever 27 remote from the elastic part 27a, there is formed a guide groove 27c, whose rocking angle is controlled by a pin protruding from the supporting plate 29. The lever 27 is given a counterclockwise turning force by a coiled spring 31, so that the driving pawl 27b is held at a position spaced from the ratchet wheel 21. Retaining pieces 32 and 33 keep the minute-indicating plate 1 and the hour-indicating plate 2 at rest till the time of their turning-over and falling, respectively. The hook part 16b is formed so that it can engage with only the minute-indicating plate 1a indicative of &#34;59&#34; minutes among the minute-indicating plates 1. 
     A calendar mechanism will now be explained. The date-indicating plates 3 and the day-of-the-week indicating plates 4 are rockably mounted at equal intervals on a date drum 36 and a day-of-the-week drum 37 secured to arbors 34 and 35, respectively. Driving mechanisms for the respective indicating plates 3 and 4 will be described with reference to FIG. 3. A date driving ratchet wheel 38 is secured at an end of the date drum 36. Day-of-the-week driving pins 39, . . . protrude from one end of the day-of-the-week drum 37. 
     At the fore end of the main shaft 12, a cam 40 is secured. The cam 40 has a crest 40a and a trough 40b. An upper part of a driving lever 41 is formed with a guide groove 42a which engages with a guide pin 43 planted on a side plate 42, a central part is formed with a through hole 42b through which the main shaft 12 penetrates, and a lower part has a pin 44 planted thereon which engages with a guide groove 42c provided in the side plate 42. Accordingly, the driving lever 41 is slidable in the vertical direction and the sliding amount thereof is controlled within a predetermined range. The driving lever 41 is formed with a date driving pawl 45 and a sliding piece 46 which slides on the cam face of the cam 40. The driving lever 41 is drawn upwards in FIG. 3 by a coiled spring 47. A day-of-the-week driving lever 48 is rockably supported by a pin 49, and a guide groove 50 formed in the lever 48 is coupled by the pin 44. The fore end part of the day-of-the-week driving lever 48 is engageable with the driving pins 39. 
     A correcting device for the calendar mechanism will be described with reference to FIG. 3. A correcting lever 53 having two arms 53a and 53b is secured to an arbor 52 of a correcting knob 51 (in FIG. 1). A date correcting lever 54 is rockably supported on an arbor 55. At one end of the lever 54 is a pawl 54a engageable with the ratchet wheel 38. At the other end is an engaging piece 54b engaging with the arm 53a of the correcting lever 53 and a coiled spring 56. A day-of-the-week correcting lever 57 is rockably supported on an arbor 58. At one end of the lever 57 is a pawl 57a engageable with the pins 39 while at the other end is an engaging piece 57b engaging with the arm 53b. A coiled spring 59 is retained between the levers 57 and 48. In order to prevent both the correcting lever 54 and 57 from feeding two or more detents, their rocking angles are controlled in such way that the extreme ends of the engaging pieces 54b and 57b are respectively engaged with stopper windows 60 and 61 provided in the side plate 42. A click spring 62 has its upper end part 62a resiliently engaged with the ratchet wheel 38, and has its lower end part 62b resiliently engaged with the pins 39 on the left side surface of the day-of-the-week drum 37. Retaining pieces 63 and 64 (in FIG. 1) keep the date-indicating plate 3 and the day-of-the-week indicating plate 4 at rest till their turning-over and falling, respectively. 
     Referring now to FIG. 4, description will be made of the shape of the minute-indicating plate 1 and the printing of minute indicating characters. 
     The minute-indicating plates 1, . . . have projections 1a and 1a on both the sides. The center line or substantially the lower edge 1b becomes the center of rocking. The left corner of the upper edge is formed into a square 1c, while the right corner is cut into an arc 1d. A notch 1e is provided at the upper edge of the indicating plate 1. The notch 1e corresponds to the retaining piece 32 when &#34;59&#34; is indicated in case of printing the minute-indicating characters as will be stated below. Sixty of the minute-indicating plates 1, . . . of such identical shape are prepared. 
     The printing of the time indicia or indicating characters will now be described. The front surface of the minute-indicating plate 1 at the time when the rocking center edge 1b lies at the base of the plate and the arc ld lies at the upper right corner, as shown in FIG. 4, is termed the surface A, while the rear surface is termed the surface B. The upper half of &#34;00&#34; is printed on the surface A 1  of the first minute-indicating plate as illustrated in FIG. 5, while the lower half of &#34;01&#34; is printed on the surface B 1 , which appears by turning over the first plate with respect to the lower edge 1b, as illustrated in FIG. 6. The upper half of &#34;01&#34; is printed on the surface A 2  of the second minute-indicating plate as illustrated in FIG. 7, and the lower half of &#34;02&#34; on the surface B 2  as illustrated in FIG. 8. Likewise, the upper half of &#34;02&#34; is printed on the surface A 3  of the third minute-indicating plate as illustrated in FIG. 9, and the lower half of &#34;03&#34; on the surface B 3  as illustrated in FIG. 10. In the same way, predetermined indicating characters are printed on the surfaces A and B of the fourth to fifty-ninth minute-indicating plates. The last sixtieth minute-indicating plate is as shown in FIGS. 11 and 12, and is bilaterally inverse with respect to the other minute-indicating plates. The upper half of &#34;59&#34; is printed on the front surface at the time when substantially the lower edge 1b is the center of rocking and the upper right corner is the square 1c, that is, the rear surface B&#39; 60 , while the lower half of &#34; 00&#34; is printed on the surface A&#39; 60  which appears by turning over the sixtieth plate with respect to the lower edge 1b. When the minute-indicating plates printed as described above are mounted on the minute drum 11, the square corner 1c of the last minute-indicating plate protrudes beyond the remaining minute-indicating plates as illustrated in FIG. 1. The retaining part 16b is engageable with only the protruding part (the square corner 1c of the last minute-indicating plate). 
     Although the minute-indicating plates 1 has been described above as being formed by printing the indicating characters after press punching, it can be quite similarly formed by performing the press punching after the printing. 
     The mode of operation of the device will now be explained. Upon the rotation of the motor, the motor pinion 5 is rotated. In interlocking relationship therewith, the gear 6, pawl 7, seat 8a, intermediate gear 9 and minute driving gear 10 are rotated. In consequence, the minute drum 11 is rotated, the upper stage one of the minute-indicating plates 1 comes away from the retaining piece 32 and turns over and falls, and the next minute indication is established. Since the indicating plates of from &#34;00&#34; to &#34;58&#34; are located so that the upper right corner of the indicating plate at the upper stage is the arc 1d as illustrated in FIG. 4, the hook 16b of the hour driving pawl 16 does not fasten the upper right corner of the minute-indicating plate. Accordingly, the upper stage of indicating plate 1 turns over and falls for the next indication when the minute drum 11 is fed to a position at which the plate gets clear of the retaining piece 32. In this manner, the minute-indicating plates 1 are driven in succession to display the minute increment of time. At the indication of &#34;59,&#34; the minute-indicating plate 1 is located so that the right upper corner is the square 1c, and the notch 1e  lies so as to just oppose the retaining piece 32. Therefore, when the minute drum 11 is fed, the notch 1e passes through the retaining piece 32 and is freed therefrom before the time at which the upper stage of minute-indicating plate 1 is to fall. The upper stage of indicating plate, however, does not turn over and fall because the hook 16b of the hour driving lever 16 engages the corner 1c of the indicating plate. Upon elapse of one further minute, the sliding part 16a of the hour driving lever 16 drops from the crest 13a to the trough 13b of the cam 13. 
     Due to such a construction, the hour driving lever 16 rocks clockwise, and the hook 16b moves upwards to release the minute-indicating plate 1. Then, the minute-indicating plate 1 turns over and falls, and the next minute &#34;00&#34; is indicated. 
     Even if the retaining piece 32 engaging with the upper stage of indicating plate 1 releases the engagement before the hook 16b is disengaged from this indicating plate, such is rather desirable for the precision of the lower digit indication. Simultaneously with the indication change of the minute-indicating plates from &#34;59&#34; to &#34;00,&#34; the ratchet wheel 21 is fed by one detent by means of the driving pawl 18, the main shaft 12 is rotated to disengage the hour-indicating plate 2 from the retaining piece 33 through the hour drum 14, and the hour-indicating plate 2 turns over and falls, so that the next hour indication is made thereby displaying the hour increment of time. 
     Since, in this manner, the hour drum 14 is intermittently driven by the hour driving lever 16 coacting with the cam 13, the center line of the hour-indicating plates 2 is normally kept stationary at the center line of the display plane. The minute-indicating plates 1 are subjected to continuous drive as the minute drum 11 is interlocked with the rotation of the drive motor. Therefore, when the sixty minute-indicating plates 1 are included as in this embodiment, a movement over 6° in terms of the central angle is continuously performed downwards from above the center line of the display plane. That is, in this embodiment, the shear between the indicated characters of the hour and the minute is at most 3° in terms of the central angle, and this value is not exceeded. Owing to the intermittent drive of the hour drum 14, any mechanism for checking the hour-indicating plates from turning over and falling till the correct time, such as is required in the case of the continuous drive, is unnecessary. Accordingly, the minute drum 11 and the hour drum 14 may be disposed in a manner to lie almost in contact, and the spacing between both the drums is diminished. 
     When the main shaft 12 is rotated by just one revolution by the sequential turnings owing to the above operation, the cam 40 also undergoes one revolution. With the rotation of the cam 40, the lever 41 is gradually pushed down by the sliding piece 46. FIG. 3 shows the state of the sliding piece 46 immediately before dropping from the crest 40a to the trough 40b. When the sliding piece 46 drops to the trough 40b at the next moment, the lever 41 is instantly slid upwards by the coiled spring 47. At this time, the date driving pawl 45 feeds the ratchet wheel 38 by one detent. Simultaneously therewith, the day-of-the-week driving lever 48 is rocked through the pin 50, to feed one pin 39. Owing to the rotation of the ratchet wheel 38 by one detent, one date-indicating plate 3 is caused to turn over and fall through the date drum 36, and the next date is indicated. Owing to the feed of the pin 39, one day-of-the-week indicating plate 4 is caused to turn over and fall through the day-of-the-week drum 37, and the next day-of-the-week is indicated. 
     Manual corrections of the indications will now be described. When the minute correcting knob 22 is turned, the arbor 23, minute correcting gear 24 and minute driving gear 10 are rotated, and the minute-indicating plate 1 is fed in the same way as described above. The rotation of the minute driving gear 10 at this time results in that the pawl 7 merely slides on the tooth 6a of the gear 6 through the intermediate gear 9 as well as the seat 8a, and it bestows no rotation. Consequently, the gear 6 is not rotated, and any unreasonable influence is not exerted on the motor, etc. When the hour correcting knob 25 is turned, the hour correcting lever 27 is rocked through the pipe 26. The driving pawl 27b therefore feeds the ratchet wheel 21 by one detent, and the hour-indicating plate 2 is thus driven in the same way as described above. When the hour correcting lever 27 is to return to the original position by the coiled spring 31, the elastic part 27a bends and causes the driving pawl 27b to escape from the detent of the ratchet wheel 21, and hence, the ratchet wheel 21 is not damaged. 
     In case of correcting the date, the correcting knob 51 is turned counterclockwise. Then, the arbor 52 and the lever 53 rotate counterclockwise in FIG. 3, and the engaging piece 54b of the date correcting lever 54 is pushed down. The pawl 54a therefore moves upwards. At this time, the ratchet wheel 38 is fed by one detent, and the date-indicating plate 3 is driven. In case of correcting the day-of-the-week, the correcting knob 51 is turned clockwise. Then, the arbor 52 and the lever 53 rotate clockwise in FIG. 3, and the engaging piece 57b of the day-of-the-week correcting lever 57 is depressed. The pawl 57a therefore moves upwards, and engages with the pin 39 to feed it. Then, the day-of-the-week indicating plate 4 is fed in the same way as described above.