Chapter 72: Dynamic Barcodes - E-Ink and Digital Displays |
At a Glance: This chapter explores the transition from static, printed barcodes to intelligent displays that can change in real-time. We examine the core technologies of E-Ink and digital displays, the role of Code 39 as a foundational symbology, and the practical applications transforming retail, logistics, and healthcare. The future of barcodes is dynamic, and machine vision is evolving to keep pace. |
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The Inevitable Shift from Static to Dynamic |
For decades, the humble barcode has been the silent workhorse of commerce. Printed in black and white, it has served as the digital thumbprint for everything from cereal boxes to critical medical supplies. This static nature is both its strength and its limitation. Once printed, the information a traditional barcode carries is fixed. A price cannot be altered, an expiration date cannot be updated, and a supply chain status cannot be conveyed without printing and applying a new label. |
We are now at the threshold of a fundamental change. The 'barcode' is evolving from a static, printed mark into a dynamic, digital display. Instead of ink on paper, these new codes are generated on electronic paper (E-Ink) or small digital screens, allowing them to change in real time to reflect updated pricing, inventory status, or product expiration. This chapter explores this transition, examining the technology behind dynamic barcodes and the practical applications that are beginning to reshape entire industries. As these codes become dynamic, machine vision systems must become more sophisticated to read them effectively in a variety of real-world environments. |
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The Foundation: The Code 39 Legacy |
Before we explore the dynamic future, it is crucial to understand the foundation upon which many of these systems are built: Code 39. Developed in 1974, Code 39 was a revolutionary symbology because it was the first barcode that could encode both letters and numbers, not just digits. This alphanumeric capability made it far more versatile than earlier numeric-only barcodes, leading to its widespread adoption across a diverse range of industries. |
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Technical Profile of Code 39 |
To understand why Code 39 remains influential, we must examine its core characteristics: |
Character Set: The standard Code 39 encodes 43 characters, including uppercase letters (A-Z), numbers (0-9), and several special characters like space, period, dash, dollar sign, slash, plus, and percent. An extended version, Code 39 Extended, can encode the full 128-character ASCII set by using two-character combinations, though this significantly increases the length of the barcode. |
Structure: Each character in Code 39 is represented by a pattern of five bars and four spaces. Crucially, three of these elements are wide and six are narrow. This 'self-checking' design means that a printing error that turns a bar wide instead of narrow is unlikely to produce a valid character, providing a built-in level of error resistance without needing a mandatory check digit. |
Variable Length: Code 39 is a variable-length symbology, which means it can encode a flexible amount of data. This is advantageous for applications where the length of the identifier may vary, such as serial numbers or part numbers. However, this flexibility comes at the cost of data density. |
Low Data Density: The most significant limitation of Code 39 is its low data density. Because each character requires five bars and four spaces, it takes up a considerable amount of horizontal space. As a rule of thumb, a Code 39 barcode with 20 characters will be approximately 53mm wide at the recommended resolution. This makes it unsuitable for very small items or applications where space is at a premium. |
Widespread Compatibility: Code 39's greatest strength is its near-universal support. Almost every barcode scanner, from the most basic laser scanner to sophisticated camera-based imagers, can read a Code 39 barcode. This wide compatibility is a major reason it continues to be used in so many industries today. |
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Industries Relying on Code 39 |
Despite its low data density, Code 39's simplicity, robustness, and universal readability have made it a mainstay in several key industries: |
Automotive and Manufacturing: Code 39 is used for asset tracking, work-in-progress tracking, and labeling vehicle identification numbers (VIN) and parts. Its tolerance for less-than-perfect printing conditions is a major asset in rugged factory environments. |
Government and Defense: The US military's LOGMARS system is a prominent example of Code 39's use in defense logistics. The symbology is also used in many other government and defense applications. |
Healthcare: The Healthcare Industry Bar Code (HIBC) standard uses Code 39 as a primary symbology. It is used to label everything from patient wristbands to medical devices and pharmaceuticals, ensuring accurate identification and patient safety. |
Logistics and Warehousing: Code 39's reliable scanning performance makes it a popular choice for tracking packages and managing inventory in warehouses and shipping centers. |
As we move to dynamic barcodes, the proven reliability and widespread scanner compatibility of Code 39 make it a logical choice for many early implementations, even as the technology evolves to support more data-dense 2D symbologies. |
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The Technologies Enabling Dynamic Barcodes |
The transition from static to dynamic is powered by two primary display technologies: E-Ink (electronic paper) and liquid crystal displays. |
E-Ink (Electronic Paper) |
E-Ink, also known as electrophoretic technology, is a display medium that mimics the appearance of ordinary ink on paper. It works by suspending charged pigment particles (typically black and white) in a fluid-filled layer. Applying an electric field moves these particles to the surface, creating the desired image. |
The key characteristics of E-Ink that make it ideal for dynamic barcodes are: |
Bi-Stability: An E-Ink display maintains its image without any power consumption. Once a barcode is written, the display draws zero power to hold it. This is why a Kindle can last for weeks on a single charge. For barcode applications, this means a dynamic price tag or shelf label can remain readable for years on a single small battery. |
Sunlight Readability: Unlike LCDs, E-Ink displays reflect light like paper, making them highly readable in direct sunlight. This is a critical feature for use in brightly lit retail environments, outdoors, or in warehouses. |
Low Power Consumption: Because power is only used when the display updates, E-Ink is incredibly energy-efficient. This allows for battery-powered systems that can last for many years, significantly reducing maintenance costs. |
These properties make E-Ink the dominant technology for applications like Electronic Shelf Labels (ESL), where the information changes only occasionally (a few times a day) but must remain visible for long periods. |
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Liquid Crystal Displays (LCD) |
LCDs are the familiar screens used in smartphones, monitors, and televisions. They function by using a backlight to shine through a layer of liquid crystals, which can be electrically controlled to block or transmit light, creating an image. |
For dynamic barcodes, LCDs offer distinct advantages: |
High Refresh Rates: LCDs can update very quickly, often in a fraction of a second. This makes them suitable for applications where the barcode needs to change rapidly, such as in a time-based loyalty system or a dynamic shipping label updated by the carrier in real-time. |
Full Color: While E-Ink is typically grayscale (though color E-Ink exists), LCDs can easily produce vibrant, full-color images. This allows the dynamic barcode to be integrated into a richer, more informative display that includes logos, color-coded status indicators, and marketing messages. |
Cost: For high-volume, simple applications, small LCD panels can be very inexpensive. |
The trade-off is that LCDs consume significantly more power than E-Ink, as they require a backlight (unless using a reflective LCD). This makes them less suitable for battery-operated devices that need to last for years without a recharge. |
Real-World Applications of Dynamic Barcodes |
The convergence of these display technologies is enabling a new wave of applications that leverage dynamic barcodes. Here are several examples across different industries. |
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Electronic Shelf Labels (ESL) in Retail |
The most widespread current application of dynamic barcodes is Electronic Shelf Labels (ESL). In a modern supermarket like Lotte Mart in Vietnam, ESLs are replacing traditional paper price tags. These small E-Ink displays are attached to the store shelves. Each label can display a barcode (often a Code 39 or a 2D code) along with the price and a description of the item. |
The Dynamic Advantage: When a price changes due to a promotion, a markdown, or a supplier cost increase, a central server sends a wireless update to the ESL. Instead of a store employee spending hours printing, cutting, and replacing paper tags by hand, the update is applied to thousands of labels in seconds. This dramatically reduces labor costs and eliminates the potential for human error where the printed price doesn't match the price in the point-of-sale system. |
Real-World Impact: At Super Nosso in Brazil, the implementation of ESLs led to a near-perfect pricing accuracy and allowed the chain to launch dynamic 'Happy Hour' promotions with ease. The clean, modern look of the E-Ink displays also contributed to a more premium shopping experience. |
Machine Vision Connection: Modern point-of-sale scanners are being designed to handle this new reality. For example, Datalogic's new Magellan scanners are engineered to read barcodes from digital displays, even if the screen is scratched, has glare, or is in motion. This capability is crucial for seamlessly scanning dynamic barcodes on ESLs that customers might bring to the register. |
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Perishable Goods and Smart Labels |
One of the most promising applications of dynamic barcode technology is in managing perishable goods in the supply chain. |
The Temperature-Tracking Barcode: Companies like Varcode are developing a 'dynamic' linear barcode that acts as a temperature-sensing label. This smart tag, developed in collaboration with Avery Dennison, is more than just an identifier. It contains a material that changes in response to temperature. As a shipment of vaccines, fresh produce, or cold-chain pharmaceuticals travels through the supply chain, the barcode itself changes to record the cumulative temperature exposure. |
Machine Vision Reading the Status: When a worker scans this dynamic barcode with a standard scanner or a smartphone, the device reads both the static identifying information (e.g., the product's GTIN and lot number) and the dynamic data indicating whether the product has been exposed to temperatures outside its safe range. The result is then transmitted to a cloud-based system for immediate visibility into the product's condition. This is a significant advancement over simple chemical indicators that only provide a yes/no answer, and more cost-effective than full dataloggers, which can be expensive. |
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Dynamic QR Codes and the Cloud Connection |
Another powerful form of dynamic barcode is the QR code that connects to a cloud resource. Unlike a static QR code that encodes a fixed URL, a dynamic QR code contains a short link or an identifier that points to a cloud server. When scanned, the server uses the identifier to fetch the latest information and redirects the user to the appropriate destination. |
The Digital Product Passport: This capability is central to the concept of a Digital Product Passport. A product's packaging might have a dynamic GS1 Digital Link QR code printed on it. When a supply chain manager scans it, they might see the product's manufacturing date, batch number, and logistics history. When a consumer scans the same code at home, they are redirected to a user manual, a recipe, or a product registration page. |
Lifecycle Management: Because the destination is controlled on the cloud, the brand can update the associated information without ever changing the packaging. This is crucial for recalls, product updates, or extending a warranty. As one industry expert notes, this dynamic capability allows brands to 'modify destinations after production, while scan analytics provide valuable insights into customer engagement'. |
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Dynamic Mail and Parcel Processing |
The postal and logistics industry is another area where dynamic barcodes are being explored. Patents describe mail items that use time-dependent barcodes using reactive inks. In these systems, a mail piece might have two barcodes. One disappears after a few days, while another appears. This could be used to automate the handling of perishable parcels or to encode a 'use by' date directly into the mail piece's label. |
Time-Sensitive Routing: The barcode could have a 'first machine readable postal information value at a first period of time and a second, different machine readable postal information value after expiration of a second predetermined time period'. This would allow a postal sorting machine to route a package one way (e.g., for express delivery) if it is scanned within a certain timeframe, and another way (e.g., for standard delivery) if it is late. |
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Self-Service and Automation |
Dynamic barcodes are also enabling new levels of self-service and automation. |
Interactive Kiosks: Imagine a kiosk at a car rental company. You arrive, check in on the touchscreen, and it generates a unique, dynamic barcode or QR code on its screen. You then hold your phone up to the screen or scan the code with a reader at the car gate. This code could contain not just a simple identifier but a dynamic key that grants you access only to the specific car you've been assigned. |
E-Tickets and Access: Already, airlines and entertainment venues are moving away from paper tickets towards dynamic barcodes on smartphone screens. These can change periodically to prevent fraud or to embed real-time information about gate changes or seat assignments. This dynamic nature is a significant security advancement over static, easily copied, paper-based systems. |
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The Machine Vision Challenge: Reading Dynamic Barcodes in Real-Time |
As barcodes become dynamic, the systems that read them must also evolve. Traditional laser scanners are optimized for static, high-contrast, printed black-and-white labels. Reading a barcode from a digital display presents several new challenges: |
Glare and Reflection: A glossy smartphone screen or an LCD display can create glare that confuses a scanner. |
Low Contrast: E-Ink displays, while high-contrast in good light, can appear less so in dim conditions. |
Non-ideal Angles: A customer may hold their phone screen at an awkward angle to the scanner. |
Motion: A dynamic barcode on a moving conveyor belt might need to be read even as it updates. |
Speed: The system needs to be fast enough to handle the refresh rate of the display and the speed of the user or item. |
To address these challenges, modern machine vision systems are incorporating several advanced features. These 'next-generation' scanners are designed to be far more forgiving. They use digital cameras (image sensors) and sophisticated decoding algorithms that can handle barcodes in motion, on curved surfaces, or on a screen. They can handle a wide range of lighting conditions and can even perform image enhancement to correct for glare or reflection. |
The future, as demonstrated by products like the Datalogic Magellan 3600VSi, is a 'hybrid reading capability' that can read not just barcodes but also RFID tags, providing a comprehensive 'tracking from stock control to point-of-sale'. This integrated approach is essential for the intelligent retail environment where items on the shelf have a dynamic label, a passive RFID tag, and are integrated into a digital inventory system, all updated and verified in real-time. |
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Conclusion |
The barcode is experiencing a profound rebirth. The journey from the 'static printed label' to the 'dynamic digital display' is a fundamental shift, not just in technology but in the very concept of what a barcode is. It is evolving from a simple, immutable identifier into a real-time, interactive portal of information that bridges the physical and digital worlds. |
The Code 39 symbology, despite its relatively low data density, has served as a critical cornerstone for many of these early dynamic systems due to its ubiquity, error tolerance, and simplicity. Its legacy is woven into the very fabric of the industries that are now at the forefront of the dynamic revolution. |
The technologies enabling this change---E-Ink and digital displays---offer distinct advantages. E-Ink provides the bi-stability and extreme low power consumption essential for applications like Electronic Shelf Labels, where information persists without energy and can be updated wirelessly in seconds to reflect prices, promotions, and inventory status. The success of ESL implementations in supermarket chains like Lotte Mart in Vietnam and Super Nosso in Brazil demonstrates that this is not a futuristic concept but a practical, cost-saving reality today. LCDs, on the other hand, offer the speed and color necessary for interactive self-service kiosks and mobile-centric applications. |
The applications are expanding rapidly across sectors. In logistics, dynamic barcodes on smart labels are becoming sophisticated environmental sensors, capable of tracking temperature exposure for sensitive pharmaceuticals. In supply chain management, dynamic QR codes that point to cloud data allow for Digital Product Passports and the ability to update product information long after the product has left the factory. Even in the postal system, early concepts explored time-dependent barcodes to manage routing based on how long a mail piece has been in transit. |
For machine vision, this evolution represents a significant challenge that is being met with intelligent solutions. The scanners of the future must be versatile, capable of reading barcodes from glossy phone screens, low-contrast E-Ink displays, and moving items, all while integrating with sophisticated software and AI to validate the information in real-time. |
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Ultimately, dynamic barcodes are a foundational technology for the intelligent, connected world. They promise to reduce manual labor, eliminate costly errors, provide unprecedented visibility into the supply chain, and create richer, more engaging experiences for consumers. The future is not a single barcode but a dynamic, data-rich ecosystem where every product is connected, every scan informs a system, and every piece of information is current, accurate, and responsive to the needs of the moment. |
cs@easiersoft.com