Hello and welcome..
Today we are going to discuss the screen display system on any Toshiba laptop.
All Toshiba laptop screens are housed within a shell that is the lid which on the majority of the model range is Plastic ABS. Some lids were made from cast aluminum (Some Porteges).
The screen though is mounted to the lid using a system of rails, these rails are mounted to the lid. There are many rails systems employed in Toshiba Laptops, and some are interchangeable with other laptops, notably the Toshiba Satellite Pro 6000, Satellite pro 4600, and the the Satellite Pro 2100/1400/2410/1410 Series Laptops as an example.
Screen rails are usually constructed of pressed steel to fit the profile for a given size of screen and to enable fixing to the base lid.
The rails are fixed usually by small screws although on some Toshiba laptops you may find that there are no rails actually fitted to the screen the lid becomes the sole mounting site for the screen.
The front bezel is made from plastic ABS, this is a flat plastic cover which conceals the rails, the screen inverter and protects the screen area from ingress and dust penetration. the bezel is moulded in such as way that it incorporates many snap lugs around the periphery of the bezel reducing the need for lots of fixing screws, the lugs will locate and lock the bezel into place. Some older machines used this combination of snap lugs and fixing screws (for example the Tecra S1 series laptops). Most modern Toshiba Laptops use the snap lug fixing method since it is cheaper to manufacture and also reduces weight and component count.
For machines that were tablets there was slight departure from the standard design because of the complexity of the touch screen and the extra weight that these extra components when assembled. With many tablets the design of the lid and the front bezel were different to accommodate the feature of rotating the screen through 360 degrees and the newer style of fold flat lids which when lifted up, and then rotated, enables the display facing upwards, resting on the profile of the main base.
The basic components of most screen display systems are,
- The Screen
- The Screen Connecting cable
- The Invertor
- The Base lid
- The Hinge mechanism
- The front bezel
- Any wireless or Bluetooth cable systems
- Lid latch and return spring assembly
I won’t discuss the exact technicalities of tablet screen systems because Toshiba did not really standardize between models so it does not merit any further discussion here.
We have already touched on some of the elements of the screen display such as the lid, the screen rails and the front bezel, I will now move on to the invertor and the other system components.
The invertor primarily functions as a lighting up circuit, its function is to supply energy to the cold cathode display tube that is manufactured at the bottom of the LCD display, this provides a back lighting system so that you can see each and every pixel being displayed on the screen without it the screen would remain dark. More modern machines have much more advanced electronics fitted into the design of the invertor, such as screen brightness settings, current overload, screen blanking, sleep adjustment and various other attributes of which includes bios control as well.
Some screens which are high definition are fitted with two invertors to increase the overall contrast and brightness of the screen and to distribute the power required by the screen tubes evenly. These are usually fitted to screens of size of 17″ or larger.
The screen connecting cable comes in four standard sizes, and is dependent on the capabilities of the screen fitted, its resolution and its overall size, the cable will supply all the control signals and power lines to the screen interface, detection of the screen type, and the actual display data to the user. The most common cable now found are the 30pin flat connector which is actually a very low current signal propagated at very high speed and then reflected back into the main system, commonly known as LVDS, we won’t discuss the technical details of this system its beyond the scope of this discussion.
The cable is connected at the other end to a graphics card switching circuit which enables the user via software or hardware detection to determine the default type of display device. If you plug in an external monitor some Toshiba laptops will default to displaying on the external monitor rather than on the LCD screen.
The hinge mechanism is an assembly that maintains the integrity of the base lid system and enables the user to adjust the screen position in on dimension, the criteria here is maintain an adequate force to hold the screen upright for extended periods of time and at the same being able to close the lid easily and without any notchiness or serious restrictions. The design on many Toshiba laptop hinge systems falls into three categories.
- Lid and hinge integrated onto the palmrest
- Lid and hinge detaches from the palmrest
- Lid detaches form a fixed hinge system on the base
Most modern Toshiba machines now fall into second category, though I feel the first category was actually the most durable, this can be seen on the Toshiba Satellite Pro 2450, Toshiba Satellite A40, Toshiba Satellite Pro 4600.Most Toshiba laptop hinge systems comprises of a cast steel pin with an outer sleeve pressed onto the outside to create the friction necessary to force the screen to remain upright, the other end of the pin is then machined with a spline which then is force fitted to the hinge surround, the hinge surround can extend under the palmrest and is then fixed to the palmrest (as in the first category) or detachable as in the second category. The hinges also form part of the lid support system with a continuous bracket system extends to enable the lid to be mounted to the hinge assembly, cutting down excessive components and weight. The more modern systems comprise of a cast post material, inserted to the base system and then fixed from the back and the undersides with screws, the hinge itself is part of the cast post system and the spline is inserted into the cast post with tremendous force, the restrictor sleeve is then mounted to the lid frame, this is the more common in the second category. The third category is not much used these days except for very small light weight laptops where weight and size dictates the screen hinge components.
The lid latch system is a simple latching assembly pre tensioned by a small cylindrical spring, allowing self retraction of the screen lid locking jaw, these are usually a claw shaped plastic component that locks into the base system. Most Toshiba laptops have used many variations of this construction and its proven reliable, since all Toshiba lid plastics and hinges components are very accurately made, alignment is maintained even through excessive wear of the hinge system or accidental damage to the lid. This construction also reduces wear on the lid locking jaw itself, the locking jaws primary function it that its strength relies on the width of the jaw and the length of the jaw when in the locking position. More modern machines are now moving to the lockess style of construction but the palmrest design and the top lid has now been redesigned to give a perceived and noticeable incline to enable the lid to remain closed (clam shell design).
Wireless cable systems are usually attached behind the screen on the lid base, their primary function is to provide a larger surface area in which to receive the appropriate wireless signals, this also applies to blue-tooth cable systems as well. Most wireless cable systems are usually an RF self adhesive pad this enables the service technician to easily replace a damaged cable.