Citizen Caliber 4921: Compact Digital Quartz Movement with Full LCD Functions

The Citizen Caliber 4921 is a compact, multi-function digital quartz movement developed for watches that require high functionality in a small, slim form factor. With a profile of just 3.75 mm thick, this movement integrates key digital features such as time, calendar, alarm, and backlight into a unified LC display. It was crafted during the peak era of LCD watch innovation and continues to be valued among collectors and watch technicians for its simplicity and robustness.

Core Features

The 4921 movement was designed to pack a wide range of digital features into a small case size without compromising legibility or usability. Key functions include:

• Digital Time Display: Hour, minute, and second are continuously visible on the LC display. Includes AM/PM indication for 12-hour mode.

• Calendar Function: Date display is integrated with time, useful for daily wear and planning.

• Daily Alarm: A sound-based reminder that can be manually configured.

• Chimes: Hourly time signal.

• Stopwatch: For basic timing and chronograph needs.

• Alarm Monitor: Allows confirmation of alarm status visually or audibly.

• 12/24-Hour Switching: User-selectable time format.

• Illumination Lamp: Integrated backlight for readability in low light conditions.

This full-feature digital module enabled Citizen to offer highly functional wristwatches with a slim profile, suitable for both men’s and women’s designs.

Technical Specifications

• Type: Quartz crystal oscillator with LC display

• Vibration Frequency: 32,768 Hz

• Display Type: Liquid Crystal (LCD)

• Size: 28.0 mm

• Thickness: 3.75 mm

Despite its slim design, the movement’s quartz base ensures accurate timekeeping, consistent with other high-quality Citizen quartz models.

Key Components and Serviceability

Citizen designed this module with service and part replacement in mind. The document lists all major replaceable parts along with catalog numbers, enabling easy ordering and servicing. Key components include:

• Plate Complete (750-825): The structural base holding the movement.

• LC Display Panel (281-833): Shows the time, date, and other indicators.

• Light Diffusing Plate (235-192): Helps with backlight illumination.

• Power Cell (280-44): Battery unit powering the movement.

• Power Cell Connector Spring (231-121) and Insulators (233-188, 233-189): Ensure safe and stable battery integration.

• Display Panel Supporter (226-184): Secures the LCD panel in place.

• Connection Rubber (268-90): Facilitates electronic connection between display and circuit.

• Supporter for Plate Complete (720-079): Additional frame support.

• Buzzer Contact Spring (902-176): Part of the alarm and chime system.

These components make the 4921 relatively easy to service compared to more complex hybrid digital-analog calibers.

Application and Design

This movement is best suited for:

• Slim digital watches

• Retro-style LCD watches

• Timepieces with alarm and chime needs

• Unisex or youth-targeted watches

Watches using the 4921 were likely aimed at casual and practical users who valued a digital display and slim, lightweight wrist presence.

Conclusion

The Citizen Caliber 4921 embodies an era of efficient digital watchmaking. With its versatile functionality, ultra-slim profile, and dependable quartz technology, it remains a desirable module for vintage restoration projects and collectors of digital timepieces. Its structured layout and documented parts list also make it a favorite among watchmakers seeking dependable serviceability and longevity.