Now in the 21st century, image display takes different patterns and are increasingly changing with new developments.

The history line of display method started from the cathode ray tube.

Cathode Ray Technology

CRT (Cathode ray tube) is a big vacuum tube that is common with the bulky TV sets of the 20 century.

To display an image, CRT uses an electron beam which scans rows of phosphors line after line on the surface of the tube. The electron beam is deflected continuously.

Digital Light Processing (DLP) Technology

Texas Instruments invented and developed DLP for rear-projection TV displays. DLP uses a chip (Digital Micro-mirror Device) for its image display technique. DMD is made up of a number of tilt-able tiny mirrors.

Each micro-mirror stands for a pixel which tilts in a rapid motion.

A gray-scale type of image results here. Colors are added when light passes through the color wheel and reflect off the micro-mirror on the chip. This reflection is formed on the screen to produce the image.

Plasma Televisions use a technique just like CRT which makes images via phosphors lighting

Plasma Technology

The characteristics of this technology are the flat, thin and wall-mount capability that it presents. It was introduced in the early 2000s. In 2014, Panasonic, LG, and Samsung that were left in the production of this display mode have all discontinued its manufacture, though the products are still in use today.

Plasma Televisions use a technique just like CRT which makes images via phosphors lighting. In this case, the phosphors are lit by superheated gas and not electron beam.

They can be lit all at once, unlike CRT which does that in rows.

LCD is not limited to backlighting technology.

LCD Technology

LCD Technology is the most used display type in TVs. They share a thin design structure as Plasma TVs. For image display, phosphors are not lit up but turned on and off at a particular refresh rate. The most common refreshed rate of LCD TVs is 120 or 60 of a second. To display an image, the LCD’s pixels must be backlit. When the pixels are ON, they allow the backlight through but when off they don’t allow backlight through. The backlight system for LCD TVs can be from any source of HCL or CCFL (fluorescent) or LED.

LCD is not limited to backlighting technology. To improve LCD TVs color, quantum dot technology is a new development on LCD technology improvements.

After the release of Retina Display in 2010, enhancing screen resolution and quality of display has seen lots of changes on our smartphones, TVs, other handheld devices and wearable displays that is still new on the market. The adoption of this newfound display technology is no doubt an improvement on the conventional designs.

Most of the display applies quantum dot technology including highly bright reflectance and high ambient displays.

Integrating quantum dots into LCD backlight results in highly saturated and bright primary colors like those of OLED displays.

Impact Of Quantum Dot Technology On LCD

Quantum dot enhances to a great measure the performance of LCD display with the aid of quantum physics. Integrating quantum dots into LCD backlight results in highly saturated and bright primary colors like those of OLED displays.

Also, quantum dots enhance brightness and power efficiency by converting blue LED lights into a greatly saturated band of primary colors for the LCD display.

A good advantage of quantum dots is that it can bring out the exact colors for images that are extremely high and accurate picture colors without the white-point errors and lopsided color range. With the incoming of quantum dots technology, the future of LCD display technology is greatly enhanced to see many more years at least in the next five years. This outstanding technology is being adopted and integrated into many LCD smartphones, TVs, and other handheld devices.

Likewise, display quality is also improved by highly bright, low reflectance great ambient light displays. Every screen acts like a mirror that reflects everything that gets illuminated in front of it. Before this form of display technology was utilized, images produced were of low output and quality of degraded contrasts and interference that makes it difficult for viewing on the screen

Today’s technology adopted by manufacturers introduces bright and non-reflective displays.

OLED Technology

OLED is the most recent in display technology designed for consumers. It combines great features of past technologies. OLED technology uses various techniques in its implementation. LG uses the WRGB process. This process brings together white OLED’s pixels with green, red and blue color filters.

The speed of DC motor can be varied by applying various techniques. The drive system comprising the drive and the DC motor is vital to speed control in DC motor.

This is to regulate the amount of energy produced by the machine and the amount of work required to be done by the system at a given time duration.

The DC drive is a simple device that regulates the amount of electrical current sent to a DC motor.

DC Motors And Drives

The DC drive is a simple device that regulates the amount of electrical current sent to a DC motor. It supplies electrical energy in varying frequencies and quantities, hence controlling the speed of the electric motor.

The use of DC motor is increasingly growing in the metal industries, in mining, printing and in crane implementation. Though the current trend is the replacement of DC motors with more efficient AC drives, the task of getting this implemented is however not time and cost effective. Using the existing motor and improving on the drive is often the best option for industries.

DC drives provide great benefits to the DC motor such as control techniques, improved motor performance, system integration and reliability of the drive system which is a key component of DC motor speed control.

The speed of a DC motor can be varied by means of mechanical or electrical methods.

Speed Control Without Microcontroller

Designing and developing a circuit without a microcontroller integrated into it lowers costs and other downsides like the limited range in the circuit design.


The speed of a DC motor can be varied by means of mechanical or electrical methods. The use of a microcontroller for speed control is gradually fading away. The disadvantage of utilizing a microcontroller in system design is the somewhat large size of the implementation.

Using Direction Control And Microprocessors

Without using microcontroller, speed control can be achieved through direction control. This is done by reversing the input voltage terminals of the motor to have the required output of energy. Two-wheeler designs are often used to implement this method. Microprocessors are other devices used to achieve speed control in a DC motor.

In this approach, sensing the current and terminal voltage is implemented. This results in comparing the reference speed of the motor to its actual speed to generate an appropriate control signal which goes into the triggering unit to cause a required output.

Pulse Width Modulation Method

PWM (Pulse Width Modulation) is a technique for producing an analog signal using a digital source. A Pulse Width Modulation signal is made up of two components namely; the frequency and the duty circle. These describe the behavior of the signal.

The duty circle defines the quantity of time the signal is in ON (high) state. It is shown as a percentage of the period it takes to make a complete circle.

The frequency of the signal defines how fast a complete circle is completed by the PWM and hence how fast it switches between Low and High states. By cycling a signal at Low and High state at a fast rate with the specified amount of duty circle, the output’s behaviors can be compared to be a frequent voltage analog signal when sending energy to devices.

Pulse Width Modulation refers to the process of varying the duty cycle. This reduces the terminal voltage with a heat loss. 555 timer can be used to implement this technique. Double Pole Double Through (DPDT) switch can be used to change the direction of the voltage. A semiconductor-type H-bridge is preferable to implement this aspect of the design on speed regulation.

Factors Affecting The Speed Of Dc Motor

The operation of a DC motor is typically designed such that when a current carrying conductor is placed within a magnetic field, there is bound to be the mechanical force that goes through the conductors. A permanent magnetic DC motor, however, does not have field circuit. It has just the armature circuit. This differentiates it from other DC motors.

The factors affecting DC control are therefore:

  • The applied voltage
  • The flux
  • The voltage across an armature

Considering these factors, speed control can then be achieved through the following techniques:

  • Flux control method: This is done by varying the current via the field winding, thus altering the flux.
  • Rheostatic control: changing the armature route resistance which also changes the applied voltage across the armature.
  • Voltage method: changing the applied voltage