VDC would be the abbreviation for Volt Direct Current which translated would volts direct current. The idea of ??this type is unidirectional current to the load. Direct current is normally produced by batteries, thermocouples, solar cells and a dynamo electric machine type. The direct current can flow in conductors such as wires, but may also flow through semiconductors, insulators ... In the image: 1 - current per pulse 2 - Direct Current (DC) 3 - Alternating Current (AC) 4 - Variable Current

Direct Thermal (Direct thermal)
Thermal printing is performed by applying heat to the printer heads. The printer head comes into direct contact with label and this turns black as heat is applied, thereby obtaining printing. For this reason, this type of thermal printers require no ribbon (ribbon) and need a special type of paper compatible with thermal printersdirect.
Thermal Transfer (Thermal transfer)
Thermal transfer printing occurs when the heat of the printer heads is applied to the ribbon (tape). Upon receiving heat, ribbon material adheres to the printing surface. For this reason a special type of paper compatible with this type of thermal transfer printers is necessary.

The degree Kelvin (K) is the unit used to classify the color temperature according to the scale created by William Thomsom from degrees Celsius. Lord Kelvin based on the table of William constructed a scale of temperatures to which its name is attributed to him.
A deeper explanation would introduce us into the world of physics, so in our sector knowing the relationship between Kelvins and kind of light will be sufficient.and.
This measurement factor is useful to know at a glance which tone or quality of light has a certain light source, for example, if we are going to buy a light bulb or a fluorescent we may be interested in knowing the kelvin it provides, as it will depend on This factor whether the light will be yellow or white.
The lower the kelvin value will be the light temperature, for example a 1600K bulb will have a temperatUra and color quality similar to the light of an exit or sunset. While a light bulb with 5000K will be more like daylight.
To better understand the relationship between kelvin and light temperature is attached the following table, where in a visual way it becomes easier to choose the type of bulb that best suits our needs.

A: It is equivalent to the temperature of a candle, it is aIn yellow light.

B: It resembles the color of dawn, it is similar to a tungsten bulb.

C: It is the tone of light of the old bulbs that were not led, filament bulb.

D: Similar to a study light.

E: Similar to mid-afternoon light about 20 °, similar to a fluorescent light warm.

F: Similar to mid-afternoon light at about 30 °.

G: Daylight, similar to a lightOf a flash.

H: Sunlight at noon.

I: Very sunny day and clear sky.

J: Partly cloudy day.

K: Cloudy day.

L: Wide shade clear day.

M: Very cloudy day.

N: Blue sky without sun.

O: Very clear day.

The COB Led (chip on board) is a plate (A) with a concentration of LEDs in the form of matrix (B) covered with a special silicone.
This type of led due to its design and installation allow to dissipate in a more efficient way the heat generated by the lighting.
It must be taken into account that the heat is generated in the opposite direction to the light and a low dissipation will cause the led to work in less optimal conditions.thus, its useful life.

Thanks to this design the Led COB is designed to work for long hours.
Its beam of light is multidirectional, so it is a type of diffuse light without dazzling at a point, achieving up to 160 º opening light and have a superior performance to the type of LED SMD.

Its manufacturing cost is 20% lower than an SMD led and its technology offers a reproducible indexchromatic ion (CRI) much higher, getting a better appreciation of colors.

In short, the COB LEDs can produce more lumens using much less energy than the rest of the LED technologies.