Electroluminescent (EL) Panels Explained​

Electroluminescent (EL) Panels Explained

EL or Electroluminescence is one of many technologies used to uniformly backlight overlays or membrane keypads. EL is applied on a very thin layer between the graphic overlay and the circuit. EL uses a printable ink deposit to illuminate the switch and provide a uniformed illumination.

EL panels are the big brother to EL wires – it has the same glow effect but with a flat shape instead of a round shape. The panel is a large sheet of flexible plastic coated with EL material so it’s like one large glowing square. The EL panel emits an even and uniformed glow over the entire shape. 

You can attach the panel by adhered it to the back of a flat surface. It is flexible but will crease and damage if folded. You can cut the panel up as long as the shape you cut out is continuous and has the cable attached. This panel is a blue-green/aqua color when lit and is the brightest of the panels as it is the natural color of EL panel.

Like all EL products, an inverter is required to operate the panel. Because EL tape has more surface area than wire, it requires a more powerful inverter. We suggest you use our 4 x AAA inverter which is strong enough to power a single panel at once. For more permanent installations, the 12V EL inverter can also power a single panel and run off 8 x AA batteries or a wall adapter.

Wearable Electronics & Technologies

Wearable Electronics & Technologies

One of the hottest and fastest growing areas in printed electronics is wearable electronics. New technologies are enabling highly conductive electronic circuits that are flexible, soft, and durable. One of the fastest-growing applications for wearable technology is in the medical field. Medical applications such as patient-worn patches require a high degree of engineering expertise. Our team of engineers works closely with medical device product developers throughout the design, testing, prototyping and manufacturing processes. CSI Keyboards also utilizes the most advanced adhesives, functional printing methods, ink selections, fabrication and assembly methods, hydro-gels, and packaging options to optimize these products’ performance and speed to market.

Other applications for wearable technologies includes wearable health sensors, consumer electronics, and sports. The wearable electronics industry is growing fast and this new application of flex circuit technology is being used more and more with greater results. The adoption of wearable technology is driving new product development and the possibilities for using this technology are endless. 

Printed clear conductive ink, silver ink, carbon and dielectric are key materials in wearable electronics manufacturing. Ink suppliers are helping to develop and advance this technology by developing new conductive inks and advanced materials. Some of the premium quality design and assembly options we offer include embossing, thin film polyester substrates, thru hole printing, and medical grade foams and adhesives. Using the best functional ink is essential in manufacturing wearable electronic circuits, and we employ the finest in the industry. These include silver/silver chloride, radiolucent conductive, zinc, carbon, and dielectric inks. We also offer a broad array of user-specific features, including sealed pouches, surface-mounted components on flexible circuits, screen printed graphics, silicone molding and custom shapes and sizes depending on the design.

At CSI Keyboards, our long history of offering leading edge solutions in the printed electronics technology makes us uniquely qualified to manufacture the finest quality, state-of-the-art wearable electronic circuits, and patch assemblies. Our circuits and assemblies are used for the most challenging applications and in the most demanding industries on the market. To meet the needs of this growing segment, we offer the broadest range of wearable circuit technology available. This includes screen printed circuits, electrodes, and sensors, all available with fast and cost-effective assembly operations.

 

CSI Develops Car Seat Pressure Sensor

CSI Develops Car Seat Pressure Sensor

CSI Keyboards recently worked with a customer in developing a seat belt reminder pressure sensor.  A seat pressure sensor is very similar to a membrane type contact sensor. The contacts of the sensor evenly distribute on the stress-bearing surface of seat, which will generate a trigger signal when the external force presses down on the seat. 

This type of sensor can be applied to any car seat occupant perception system, such as: a safety belt reminder, taxi automatic message accounting system, airbag sensor, and can also detect when an occupant leaves the seat. 

Sensor Parameters:

  • Ambient temperature: 20℃ ± 5℃
  • Rated working voltage: 13.5V
  • Rated long-time working current: ≤10mA
  • Short-time/Pulse working current: ≤20mA
  • Limit voltage: 19VDC
  • Insulation resistance: ≥100MΩ
  • Loop resistance: >40Ω

Advantages of Using Light Guide Film for Backlighting Membrane Switches​

Advantages of Using Light Guide Film for Backlighting Membrane Switches

Light Guide Film is designed to evenly distribute light from top or side firing LEDs, providing bright, uniformed illumination. It also reduces the amount of LEDs needed, saving power consumption. More on light guide film technology below. The design and utilization of light guide film (LGF) technology has become one of the most common methods of interface backlighting. CSI Keyboards uses proprietary techniques to design the light guide film so it is optimized for light redirection and reflection giving the customer the brightest possible backlighting solution. Light guide film dots are also designed and implemented which allow for the optimization of light distribution to obtain maximum brightness and uniformity. Common problems that many of our competitors face are light leakage and hot spots. CSI’s backlighting designs prevent any light leakage and hot spots from occurring, and also result in much brighter light guide film and interface.

The design typically consists of 1-4 side-firing LEDs as the light source. Hot pressing optical patterns or micro lens on the surface of the PC film to refract lights guided by the PC film. It can be easily assembled with dome switch or molded in keypad. 

The Features and Advantages of Light Guide Film are as follows:

Slim & Sleek Design

1. PC/PU/TPU film with optical pattern design (.125 – .30 mm thick)

2. Surface light source

3. High uniformed brightness

Cost

1. 50% cheaper than EL panels

2. 40% cheaper than using standalone LEDs

Energy Consumption

1. 6 LEDs light: 90mA. (LED: 15mA/pcs)

2 . LEDs + LGF: 40mA. (LED: 20mA/pcs)

Durability

1. LED light source offers 50,000 hours of life.

2. PC film is extremely durable and can function in bothhigh or low temperatures.

Use the Light Guide Film (LGF) for Keypads or LCD backlighting allows for backlighting only where needed. The CSI solution allows for uniform distribution of light regardless of the distance from LEDs. It also allows for segmentation of areas to avoid light leakage between areas or colors.

What Industries Use Membrane Switches?​

What Industries Use Membrane Switches?

CSI Keyboards designs and manufactures user and human machine interface products for a wide variety of industries. CSI has designed keypads that are used in medical instrumentation designed to be sealed from moisture and contaminants. Our membrane switches are also utilized in industries such as electronic test and telecommunication networking equipment. Industrial controls and fitness equipment are also industries where membrane switches are the user interface of choice. We have produced keypads for the military which help save lives overseas, as well as keypads for medical equipment to help save lives here at home. CSI has also developed and manufactured products to be used out on the sea, and others for air and space travel. CSI has designed and assembled custom food equipment keypads, custom lighting control keypads, custom appliance keypads, CAN/BUS custom keypads, custom automotive keypads, and custom fitness keypads. 

No matter the industry or application, we are always eager to demonstrate our extensive capabilities as one of the top keyboard manufacturers in the world. Below is a list of some of the industries that we have served over the last 35+ years:

  1. Medical
  2. Military
  3. Industrial Controls
  4. Aerospace
  5. Marine Navigation
  6. Lighting & Lighting Controls
  7. CAN/BUS Controls
  8. Food Equipment
  9. Appliance
  10. Automotive
  11. Fitness
  12. Sporting goods

What Are the Advantages of Using Capacitive Touch Switches?​

What Are the Advantages of Using Capacitive Touch Switches?

What are Capacitive Switches?

A capacitive switch is a type of touch-controlled electrical switch that operates by measuring change in capacitance. It works in the same manner as a typical capacitive smartphone: when you touch the surface, a small electrical charge is transferred from your body to the switch, which subsequently causes a change in capacitance. The switch detects this change, responding with the appropriate command.

Upon touching a capacitive switch, this electrical charge disturbs the switch’s own electrical charge; thus, causing a change in capacitance. Because of this change, the switch can identify when and where the touch occurred.

Capacitive Switch Construction:

A capacitive switch consists of three main layers, the graphic overlay, the circuit, and the backer:

  • The overlay consists of the graphic artwork and can also include windows, embossing, coatings, adhesives, and selective texturing.
  • The circuit switch will either be a Flexible Printed Circuit or a Printed Circuit Board.
  • The backer is the final part of the capacitive switch, and may or may not include an adhesive that must bond to your specific substrate. The most common materials used for overlays are plastic, acrylic, and glass due to their durability and versatility.  

Capacitive touch switches are widely used in aerospace, military equipment, medical instruments, intelligence control, commercial appliances, security products, etc.  Capacitive touch interfaces are also widely used in the fields of consumer electronics, household appliances, car security system, LED application, lamps lighting decoration application, solar photovoltaic application, sound, mobile terminal tablets, etc.

Major Features of Capacitive Switches:

  1. Beautiful and aesthetically appealing appearance; strong graphic clarity; straight-forward design.
  2. Sealed design ensuring top performance and wear resistance; anti-fade and non-deformation; long life span.
  3. Waterproof and anti-interference.
  4. No metal contact; simple structure; low cost.
  5. Operation comfort; excellent sensitivity.
  6. It can realize intellectualization and operate more conveniently.
  7. Its reliability can replace various panels, such as metal keypads, membrane keypads, etc.
 

Product Advantages:

There are no mechanical components in a capacitive switch, resulting in a longer lifespan when compared to their mechanical counterpart. Additionally, capacitive switches can withstand some of the harshest environments, including outdoor environments. If the intrusion of dirt, dust or moisture is a concern, capacitive is probably the best option for an electrical switch.

The key thing to remember about capacitive switches is that they require direct contact with a conductive object to operate. This is why using a stylus typically won’t work (unless it’s a capacitive stylus). Capacitive touch control switches can actually detect the touch of a finger through more than 20mm thick of an insulating material shell, such as tempered glass or plastic film. It ensures that the product’s sensitivity, stability, reliability are not changed with ambient conditions and long-term use, and has the waterproof and anti-interference ability.

Capacitive touch control switches do not require the user to touch metal directly, which can eliminate potential safety hazard. The part of touch circuit is placed on the back of insulating material shell, it is easy to make a keypad sealed with the surroundings. It has no any mechanical components, doesn’t wear out, has long a lifespan, and can reduce the later maintenance costs.

Standard Environmental Specifications for Membrane Switches

Standard Environmental Specifications for Membrane Switches

Due to the customized nature and the wide variety of membrane switch designs, it can be somewhat challenging to outline a general set of specifications that covers all membrane switches.  We’ve done our best to to listed below some basic environmental specifications.

  • Humidity: 0 to 98%, no condensation
  • Operating Temperature: -28.9°C (-20°F) to +70°C (+158°F)
  • Storage Temperature: -40°C (-40°F) to 70°C (+158°F)
  • Salt Fog: 5% salt solution, 48 hours
 

It is important to understand the above standard environmental specifications when designing your membrane switch. Environmental factors are a critical aspect of not only the keypad but the end product itself. Many of CSI Keyboards’ customers require environmentally sealed switches and keypads built to last in extreme and harsh environments. CSI Keyboards has over 35 years of experience designing keypads that are completely environmentally sealed and switches that need to meet specific requirements for Water, Temperature, Humidity, Dirt, Dust, Altitude, Impact resistance, Vibration, and Chemical resistance.

Some of our technologies for environmentally sealing keypads include the Seal Frame design, rubber keypad sealing designs, copper flex circuitry, environmentally resistant polyester technology, and other proprietary sealing techniques.  More information can be found in our Environmental Sealing section of the website.

Membrane Switch Overlay Material Guide

Membrane Switch Overlay Material Guide

Due to the customized nature of membrane switch designs, it can be somewhat challenging to choose the proper overlay material. There are a few major factors that must be considered when choosing the overlay material including but not limited to the finish, thickness, and environment. CSI has outlined the materials in the guide below to make this process easier and less daunting.

Venting Membrane Switches: How is it Done?

Venting Membrane Switches: How is it Done?

Venting: 

When a key is pressed in a membrane switch, the air pressure within the switch cavity increases. In order for the switch to close properly, air within
a switch cavity must be displaced, equalizing the internal pressure. There are two standard venting methods that can solve this issue:

Internal Venting: 

Designing narrow channels between key location cutouts (in the spacer layer) allowing the air from one key to move to another key locatoin when that key is pressed. 

External Venting: 

Similar to internal venting, narrow channels between keys are cut into the spacer layer. These channels then exit through the sides, rear, or internal cut-outs of the membrane switch. External venting is not recommended for membrane switches exposed to harsh environments, as there is a greater risk of contamination. 

Standard Electrical Specifications for Membrane Switches

Standard Electrical Specifications for Membrane Switches

Due to the customized nature and the wide variety of membrane switch designs, it can be somewhat challenging to outline a general set of specifications that covers all membrane switches.  We’ve done our best to to listed below some basic electrical performance specifications.

  • Contact Material: silver, carbon, gold or nickel
  • Voltage: 30 volts DC
  • Rated Current/Voltage: 20mA@30 volts DC resistive load
  • Contact Bounce: < 20 milliseconds
  • Loop Resistance: The loop resistance of a switch is a function of trace width and length. In most applications the maximum loop resistance is less than 100 ohms.
  • Dielectric Strength: 5000V max on polyester material 
  • Open Circuit Resistance: 10 ohms
  • Capacitance: 20 picofarads
  • Maximum Switch Power: 1 watt
  • Design Configuration (illustrated below): Common Bus, XY Matrix, or Custom