Big Date Display Mechanism for Wristwatch
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Solution Overview
Problem
Conventional date display mechanisms for timepieces, particularly portable wristwatches, face limitations in displaying large date numbers due to the small angular sectors occupied by each indexing position, leading to a maximum size constraint for displayed digits and requiring a large number of separate parts, which complicates the gearing mechanism and reduces reliability.
Innovation Solution
A date display mechanism of the 'big date' type that balances indications between two moving parts by truncating certain unit indications on a modified tens disk, allowing each part to carry the same number of display indications, facilitating a more reliable and compact design by integrating the control mechanism into the center of the ring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional annular date disc with 31 sectors is used, then the date can be displayed, but the angular sector for each digit is small (less than 12 degrees), which limits the maximum size of displayed numbers
Solution Approach 1:
The date display is segmented into two separate mobiles: a first mobile for displaying unit digits (0-9) and a second mobile for displaying tens digits (0-3). Each mobile has its own dedicated display sector, allowing each digit to occupy a larger angular space and be displayed in a larger font size.
Solution Approach 2:
The patent transitions from a single-dimensional display (one disc showing all 31 dates) to a two-dimensional display structure (two separate mobiles displaying units and tens digits independently). This dimensional change allows each digit to have its own display space, increasing the overall display size and readability.
2Illumination intensity
If two separate mobiles are used for displaying tens and units digits, then larger date indications can be displayed, but the number of parts increases and the gearing mechanism becomes more complex
Solution Approach 1:
The patent combines the two separate mobiles (units and tens digits) into a single integrated rotating assembly where both mobiles are fixed to the same rotating member. This merging reduces the number of independent moving parts and simplifies the gearing mechanism while maintaining the ability to display both digits simultaneously.
Solution Approach 2:
The single rotating member serves multiple functions: it carries both the first mobile for units digits and the second mobile for tens digits, and it is driven by a single gearing mechanism. This multi-functionality reduces overall device complexity while achieving the goal of large date display.
3Loss of information
If the first unit display mobile carries the complete sequence of digits 0-9, then all unit indications can be displayed, but the tens disc must carry more indications, making the sequence arrangement difficult and limiting character size
Solution Approach 1:
The patent applies local quality by assigning different digit sequences to different mobiles based on their specific functions: the first mobile carries digits 2-9 (truncated sequence optimized for units display) while the second mobile carries digits 0-3 (optimized for tens display). This localized optimization allows each mobile to have appropriately sized characters for its specific purpose.
Solution Approach 2:
The patent changes the parameter of digit sequence completeness by using a truncated sequence (2-9) on the first mobile instead of the complete 0-9 sequence. This parameter change allows better spatial distribution of indications on each mobile, facilitating larger character sizes while still displaying all necessary date information when combined with the tens mobile.
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 2A~2D
AI summary
Large date display device for a watch movement comprising a first mobile (M1) and a second mobile (M2), arranged to display, on certain dates, first date values (Q1) by combination of indications carried by said first mobile (M1) and indications carried by said second mobile (M2), and on other dates, second date values (Q2) by the indications carried by said second mobile (M2) alone.The first mobile (M1) is a modified units display mobile, bearing a first series (I1) of indications comprising a first sequence (U1) of at most nine consecutive first units digits (u1), truncated by at least one second units digit (u2) compared to the complete series of ten units, and the second mobile (M2) is a modified tens display mobile comprising a second series of indications (I2) for the display of at least the tens of the date, comprising at least one combination of two digits formed from a tens digit (d) and a second units digit (u2).