1. Introduction

In today's fast-paced world, clock display systems have evolved beyond simple timekeeping tools to become a fusion of technology and design. They not only track time but also serve as essential elements in daily life. This paper first investigates and summarizes a series of articles to analyze the differences and unique features of clock display tools across different eras. Mechanical clocks, with their intricate gears and mechanisms, represent humanity’s early pursuit of time accuracy, showcasing craftsmanship and historical significance.

As technology advanced, seven-segment displays became a critical component of modern electronic devices due to their high brightness, low power consumption, and quick response. Stereoscopic display technology further enhanced time displays, providing users with a novel visual experience through 3D projection. Secondly, the paper examines the application of clock display systems across various fields, exploring how they improve efficiency and enhance user experience in consumer electronics, industrial automation, medical devices, smart homes, automotive, and aviation sectors [1]. Devices like smartwatches, smartphones, and in-car navigation systems rely on precise, intuitive time displays while also offering notifications, health monitoring, device control, and navigation updates. These systems can even sync with global time standards, ensuring safe and timely travel. With the advancement of technology, clock display systems have become more intelligent and interconnected, serving not only as platforms for information transmission but also adding aesthetic value. Smart clock systems can now be personalized according to user preferences, displaying customized content such as weather forecasts, news, and social media updates, making them more than just timekeeping tools.

2. Type and principal analysis of clock display

2.1. Mechanical clock display

The history of mechanical clocks dates back to the 13th century, when clocks were mainly used in churches and public places to help people carry out religious activities and daily affairs on time. With the continuous progress of science and technology, mechanical clocks have gradually become the representative of precision technology. In the 18th century, due to the arrival of the Industrial Revolution, the production of mechanical clocks achieved scale, further promoting its popularity in society. Today, the mechanical clock is not only a time-keeping tool, but also a cultural heritage and artwork, carrying a rich historical background and human wisdom.

The power source of the mechanical clock mainly depends on the spring. The principle is to rely on the thought of twisting, so that the spring will curl and tighten, and then the coiled spring will release tension to drive the mechanical clock to work. The force generated from the spring will be transmitted through the gear system to the pointer to maintain its rotation. In order to ensure the accuracy of time, mechanical clocks usually have a mechanical device for time calibration, which is typically a pendulum, whose periodic motion can help the clock to control the time stably [2]. For small mechanical clocks, a speed regulating device will be applied to adjust the rate of energy release to ensure that the pointer move at a constant rate and can be carefully calibrated to the time.

Mechanical clocks are known for their exquisite workmanship and high durability. Despite the emergence of more portable and simpler clocks, mechanical clocks still have their place. In science, because of its stable and undisturbed timing function, it is used in a variety of scientific experiments. At the same time, it is also considered a work of art, and its exquisite mechanical structure and unique appearance make it the highlight of many interior decorations. As a product that has existed in history for several centuries and has far-reaching influence, its historical value is very great.

2.2. Seven-segment digital tube display

Since the 1970s, seven-segment nixie tube display have been widely used in electronic display technology. Because of its simple structure and easy to read characteristics, it is mainly used in electronics, household appliances and calculators. With the development of technology, the seven-segment nixie tube display has gradually become the standard component of digital display, especially in the electronic clock, instrument, display and so on [3]. Today, despite more advanced display technologies such as liquid crystal displays and light-emitting diode matrices, seven-segment nixie tube display still maintain an important position in the market, especially in some scenarios that require concise digital displays.

The seven-segment nixie tube display consists of seven long LEDs arranged in the shape of an "8", some with a dot LED for the decimal point. Each LED tube represents a specific part that lights up the corresponding LED tube by controlling the on-off of the current, thus displaying a different number. For example, when the number "0" is displayed, in addition to the middle LED tube, the other LED tubes will be lit. A seven-segment nixie tube display is usually combined with a microcontroller or counter to receive a control signal from a GPIO (General Purpose Input/Output) port and display the desired number.

The main features of a seven-segment nixie tube display include high brightness, low power consumption and good visibility. It is widely used in digital clocks, car instruments, traffic lights and other scenes that need to provide a clear digital display. In addition, because of its simple structure, many educational and experimental projects also use seven-segment nixie tube display to help students understand basic electronic circuits and display principles. Although liquid crystal displays and LED matrix displays are becoming more and more popular, seven-segment nixie tube display have absolute advantages in terms of ease of use and low cost, so in some basic measurements such as electronic scales, it can provide a clear and readable display at a lower cost.

2.3. Stereoscopic projection screen time display

The stereoscopic projection screen time display is a new type of equipment rising with the development of display technology. It is designed to provide a more intuitive and immersive presentation of temporal information, especially in areas such as modern smart homes, business displays and training. With the increasing demand for visual effects and interactivity, traditional flat displays have gradually failed to meet the expectations of high-end users. Therefore, with its unique three-dimensional effect and dynamic display ability, the stereoscopic time display has become an important tool to attract the attention of customers and users.

3D holographic time display technology relies on laser interference and diffraction principles. When the laser illuminates the hologram of time information, the interference image of the time is recorded on the photosensitive material, which contains the intensity of the light as well as the phase information. When the laser is shone on the light-sensitive material again, the information is reproduced and a three-dimensional image is formed [4]. The reconstructed image looks like it is suspended in the air, and users can observe it from different angles to experience a true three-dimensional effect.

3D stereoscopic time display technology has many typical characteristics. For example, it provides a strong sense of three-dimensional, enhances the visual experience, and makes the image more vivid and intuitive. In terms of smart home, 3D three-dimensional time display technology provides a fashionable and high-tech time display device, which enhances the sense of science and technology in the home environment. At the same time, this technology can help enterprises attract customer attention and enhance product attractiveness in business display. It can be seen that this technology has a wide range of application prospects in many fields.

2.4. Multifaceted comparison of various clock displays

In the field of display technology, time display devices come in a multitude of forms, each exhibiting distinct features regarding display effect, resolution, cost, manufacturing complexity, durability, and reliability. From traditional mechanical clocks to advanced 3D display technologies, each device meets different application scenarios and user needs in its unique way. The following table 1 compares several main types of time display devices to showcase the differences among them across various technical dimensions.

Table 1: Comparison of several main types of time display devices

3. Application scenario analysis

3.1. Consumer electronics

In consumer electronic products, the needs of clock display devices are diverse, they not only meet the basic time display function, but also integrate more information display and interaction functions. Users expect these devices to provide clear and easy to read displays with good energy efficiency and response speed. In addition, with the trend of personalization and intelligence, users also want the clock display device to be able to seamlessly connect with the smart home system, and even support personalized customization and touch interaction.

An article published by Yuge Huang et al. on the comparison of Mini-LED, Micor-LED and OLED found that compared with traditional leds, OLED is better in terms of color saturation, contrast, response speed and so on [5]. At the same time, because the material used is organic, its ductility will be more powerful, so it is more suitable for mobile devices such as smart phones and smart watches. However, Mini-LED and Micor-LED, as emerging display technologies, have potential advantages in brightness, energy consumption and reliability, and are expected to compete with OLED in the future in the field of large-size display. Of course, in recent years OLED is still in the field of consumer electronics occupy a mainstream position [6]. Folding screen mobile phones have become the next direction of development in the mobile phone field. The application and development of polyimide in folding AMOLED display written by WANG He-jin et al. mentioned the basic properties required by flexible AMOLED, such as high temperature resistance, low expansion, high transparency, impact resistance, etc., and looked forward to the development of polyimide in two key materials, flexible substrate and flexible cover plate [7].

3.2. Industrial environments

In the past industrial production, the demand for clock display mainly stems from the strict requirements for time management and production scheduling. However, industrial environments are often filled with harsh conditions such as dust, moisture and extreme temperatures, which challenges the performance of clock displays. In order to ensure that workers can clearly see the time, the display needs to have high brightness and durability. In the early days, many factories used LED digital tubes and large digital displays, which can maintain good readability in bright light and harsh environments, while having a long service life and low power consumption.

With the development of technology, industrial displays are beginning to integrate more intelligent functions. At present, the most used liquid crystal display (LCD) in the market, they have been widely used in industrial automation control systems with low power consumption, high resolution and high clarity. Modern industrial displays also commonly adopt touch screen technology, providing an intuitive user interface that allows operators to interact with the device more easily. Industrial displays are expected to trend towards higher definition and higher brightness display effects to meet the needs of complex work environments and multitasking. The application of new display technologies, such as flexible screens and GaN nano-and micro-LED, indicates that industrial displays will have more diversified forms and a wider range of application scenarios [8, 9].

3.3. Medical devices

In the medical field, the application of clock display devices is crucial, they not only need to provide accurate time display, but also meet the special requirements of the medical environment, such as high brightness, dust, water resistance, anti-interference and so on. Clock display devices on early medical devices needed to be stable and accurate in a variety of medical environments, such as operating rooms, ICU, diagnostic equipment, etc. Traditional solutions include the use of LED nixie displays, which are widely used for their high brightness and durability.

With the digital transformation of the medical industry, clock displays on medical devices are also beginning to integrate more intelligent functions. For example, modern medical displays often feature high-resolution LCD screens that clearly display medical images and patient information while supporting touch control, making it easier for doctors and nurses to interact with the device. Steve Langer et al. published an article on ROC studies of four LCDS and found that there are significant differences in image quality between different LCD displays. It is necessary to select the right LCD display for medical diagnostic applications [10]. In particular, it is mentioned in an article that virtual retinal display (VRD) technology has a broad application prospect in the medical field. VRD technology provides accurate medical imaging, enhances surgical vision, and assists in diagnosis and procedures. For example, VRD technology can project important flight information directly onto the pilot's retina, improving situational awareness, and this technology can be used in the medical field to provide accurate visualization of body parts and organs to aid surgery and treatment [11].

3.4. Smart home and Internet of Things

The rapid development of smart home and Internet of Things technology has put forward new demands for clock display devices. In the past, people might only need a simple digital or analog clock to show the time. However, with the advancement of technology, clocks have evolved from a single time display function to a smart device that integrates multiple functions such as weather, calendar, alarm clock, etc. These smart clocks can be connected to the Internet through Wi-Fi, achieve automatic calibration of the time, and can display weather information, temperature and humidity, etc., providing users with more convenience.

Satyendra K. Vishwakarma et al. 's article on intelligent and energy-efficient home automation systems using the Internet of Things refers to the efficient use of home energy through intelligent control and energy management [12]. In a smart home environment, the clock is no longer just a stand-alone device, but has become an integrated control center. It can interact with other smart devices such as lighting systems, security cameras, smart sockets, etc., to achieve linkage control. For example, a smart clock can automatically turn on the coffee machine or adjust indoor lighting at a set time, enhancing the user experience. In addition, holographic projection technology can form three-dimensional images in the air, which means that the clock can display time and other information in a more intuitive and interactive way. Users may be able to interact with the clock in three dimensions, such as by using gestures to set an alarm or check a calendar [13].

3.5. Automotive and aviation

In the automotive sector, early clock displays were relatively simple in design and were usually only used to display the time and meet basic reading needs. As technology advances and consumer expectations for in-vehicle device functionality increase, these displays are starting to integrate more functions, such as temperature displays, radio information, and more. The size is also gradually increasing to accommodate more information display and improve visibility [14]. The emergence of touch technology makes the display not only a passive display of information, but also an important interface for human-car interaction. LCD, OLED, mini/micro-LED and other display technologies are widely used in automotive displays due to their high definition and low energy consumption characteristics [15].

In aviation, the evolution of clock displays has gone through a similar process. Initially, displays on airplanes were used primarily to display time and other basic flight parameters. With the development of avionics, displays began to integrate more flight information, such as speed, altitude, navigation data, and so on. These displays typically feature highly reliable display technology to ensure clear information in all flight conditions.

HUD technology was first used in aviation, where it greatly improved flight safety and efficiency by projecting critical flight information into the pilot's line of sight [16]. This technology reduces the number of times pilots need to look down at their instruments, allowing them to better focus on the external environment. With the development of HUD technology, it began to be introduced into the automotive field, also bringing significant safety advantages. Vehicle HUDs project speed, navigation instructions, and other important information into the driver's line of sight, reducing the driver's eye diversion and reducing the risk of accidents.

4. Conclusion

Mechanical clocks have a long history, originating in the 13th century and initially used in churches and public places to carry out religious activities and daily affairs. With advancements in technology, mechanical clocks have gradually become symbols of precision. The Industrial Revolution in the 18th century enabled large-scale production of mechanical clocks, further promoting their popularity in society. Today, mechanical clocks serve not only as timekeeping tools but also as cultural heritage and artwork, embodying rich historical significance and human wisdom.

The seven-segment digital display has been widely utilized in electronic display technology since the 1970s. Its simple structure and legibility make it ideal for electronic devices, household appliances, and calculators. With technological development, seven-segment displays have become standard components of digital displays, especially in electronic watches and instrument displays. Despite the emergence of advanced technologies like liquid crystal displays and LED matrices, seven-segment displays continue to hold their ground in markets that require concise digital information.

Stereoscopic projection screen clock display technology has emerged with advancements in display technology. This innovative equipment provides more intuitive and immersive time information, making it particularly suitable for modern smart homes, commercial displays, and training. As the demand for visual effects and interactivity increases, traditional flat displays struggle to meet high-end user needs. The stereoscopic clock display, with its unique three-dimensional effect and dynamic capabilities, has become an important tool for capturing customer and user attention.

In the future, as augmented reality, virtual reality, and holographic projection technologies mature, clock display devices may evolve into three-dimensional or holographic displays, offering users immersive experiences. Industrial displays are expected to trend toward higher definitions and brightness to accommodate complex work environments and multitasking. The introduction of new technologies, such as flexible screens and GaN nano/micro-LEDs, suggests that industrial displays will present a more diverse array of forms and applications. Additionally, in the medical field, clock display devices are anticipated to become more diverse and intelligent, with flexible screens being used in wearable medical devices and micro-LED screens expected to enhance large displays in operating rooms due to their brightness and low power consumption. Overall, as technology progresses, we are likely to see innovative display devices integrated into the automotive and aviation sectors, providing seamless and intuitive presentations of information.