Slot Machine Peripheral Devices (continued) CRTs, LCDs, and Touch Screens

Overview Items to be covered: CRT Monitors Overview Specifications Functions LCD Monitors Operation Types Touch Screens Overview Types

Cathode Ray Tubes (CRTs) Overview Definition A vacuum tube that emits a focused electron beam from the back of the tube to the front of the tube. The front of the tube is coated with phosphors that glow when they are struck by the electron beam. An image is created by moving the electron beam back and forth across the back of the screen. The beam moves in a pattern from left to right, top to bottom and then it repeats.

Cathode Ray Tubes (CRTs) Overview Description Was developed by Ferdinand Braun, in 1897 Used in the first television sets until the late 1940s Slim neck and tapers outward until it forms a large base. The base is the viewing portion and is coated on the inside with a matrix of thousands of tiny phosphor dots. Phosphors are chemicals which emit light when excited by a stream of electrons: different phosphors emit different colored light. Each dot (aka pixel) consists of three blobs of colored phosphor: one red, one green, one blue.

Cathode Ray Tubes (CRTs) Specifications Key items Resolution Refresh Rate Interlaced or Non- Interlaced Resolution Resolution is the number of pixels the graphics card is driving Expressed as a horizontal by vertical figure. Standard resolutions is 800 x 600 pixels 1024 x 768 pixels and higher Refresh Rate Refresh rate, or vertical frequency, is measured in Hertz (Hz) Represents the number of frames displayed on the screen per second.

Cathode Ray Tubes (CRTs) Specifications Refresh Rate World-wide accepted refresh rate for a flicker-free display is 70 Hz and above Multi-scanning or "autoscan" monitor is capable of locking on to any signal which lies between a minimum and maximum refresh rates. Interlacing An interlaced monitor is one in which the electron beam draws every other line, Say one, three and five until the screen is full, then returns to the top to fill in the even blanks (say lines two, four, six and so on). An interlaced monitor offering a 100 Hz refresh rate only refreshes any given line 50 times a second, Gives an obvious shimmer.

Cathode Ray Tubes (CRTs) Specifications Game Input Signals Analog Signals RGB video signals From video circuit on processor board Aspect Ratios Ratio of width to height of a display The original aspect ratio utilized by the movie, television, and computer industries was 4:3 or 4/3 = 1.33 Decided in the late 19th century by Thomas Edison for movie industry Four units wide by three units high HDTV used 16:9 or 16/9 = 1.77 Standard Cinema Widescreen = 1.85 CinemaScope Widescreen = 2.35

Cathode Ray Tubes (CRTs) Functions

Cathode Ray Tubes (CRTs) Functions The video interface circuit usually programmable +Analog AC or -Analog coupled, DC coupled, or 4 line TTL coupled Auto bias circuit if present eliminates the need for the color setup procedure The horizontal size control circuit if present, permits the horizontal size to be adjusted remotely This circuit is also used to compensate for pincushion distortion and blooming Flyback Transformer Generate a 25,000 volt (EHT) potential for the anode of the tube Used to light up the phosphor on the face of the picture tube Beam currents of a few milliamps are typical

Cathode Ray Tubes (CRTs) Functions Placed in a frame for easy replacement Power and data inputs usually made when sliding the monitor frame into the machine on slant tops and with a few connections on uprights

Liquid Crystal Displays How LCD and LED displays differ. LED Displays: Active segments emit light Draw relatively high currents especially when using batteries Uses DC voltages to activate LCD Displays Active segments don’t reflect light/inactive ones reflect Draws very little current Uses AC voltages to activate (25 – 60 Hz) Less than 25 Hz would cause flicker Ronald Tocci/Neal Widmer/Gregory Moss Digital Systems: Principles and Applications, 10e Copyright ©2007 by Pearson Education, Inc. Columbus, OH All rights reserved..

Liquid Crystal Displays LCD operation Segment Off State No voltage between segment input and the backplane Segment reflects incident light like the surrounding part of the display Segment On State 3-15V ac between backplane and the segment input Segment doesn’t reflect incident light and appears dark Ronald Tocci/Neal Widmer/Gregory Moss Digital Systems: Principles and Applications, 10e Copyright ©2007 by Pearson Education, Inc. Columbus, OH All rights reserved..

Liquid Crystal Displays Driving an LCD The AC signal is usually replaced by a 0-5VDC square wave that is out of phase with the clock The output of the decoder is feed into 2-input XORs The other leg is feed the clock The clock also feeds the display backplane The active segments have inverted signals on their inputs and are dark The others have the same signal on both and match the background Ronald Tocci/Neal Widmer/Gregory Moss Digital Systems: Principles and Applications, 10e Copyright ©2007 by Pearson Education, Inc. Columbus, OH All rights reserved..

Liquid Crystal Displays Types of LCDs Simple 7 Segment Displays Alphanumeric displays such as: 1 line by 16 characters 4 lines by 40 characters etc. Large scale displays 640 by 480 pixels And much larger e.g., 1920 by 1080 (1080P) Color Active and Passive displays Ronald Tocci/Neal Widmer/Gregory Moss Digital Systems: Principles and Applications, 10e Copyright ©2007 by Pearson Education, Inc. Columbus, OH All rights reserved..

Liquid Crystal Displays Types of LCDs Color Displays Each pixel is actually three Red, Green, and Blue Each horizontal line of resolution actually has three connections not one – a connection for each color Thus a 640 by 480 display has 2400 connections Passive and Active displays Passive displays have all the control circuitry external to the display and are much slower to change the display An active element on the screen makes those displays much faster Ronald Tocci/Neal Widmer/Gregory Moss Digital Systems: Principles and Applications, 10e Copyright ©2007 by Pearson Education, Inc. Columbus, OH All rights reserved..

Liquid Crystal Displays Installations Available as replacements for CRTs Come mounted on the same types of frames as CRTs Replacement for Slant-top CRTs

Liquid Crystal Displays Installations Also as original display Picture at the right is from a WMS as a Bluebird machine

Touchscreens Overview Touchscreens systems come in three technologies each having three components: The technologies are: Surface Acoustic Wave (SAW) Resistive and, Capacitive Information provided to the slot machine X, Y coordinates of the point touched Used as substitute for button activation Surface Acoustic Wave (SAW) It is based on sending acoustic waves across a clear glass panel with a series of transducers and reflectors. When a finger touches the screen, the waves are absorbed, causing a touch event to be detected at that point (X, Y coordinates)

Touchscreens Surface Acoustic Wave (SAW) It is based on sending acoustic waves across a clear glass panel with a series of transducers and reflectors. When a finger touches the screen, the waves are absorbed, causing a touch event to be detected at that point. Advantages High touch resolution High clarity No-drift operation, so doesn't need re- calibration often

Touchscreens Surface Acoustic Wave (SAW) Disadvantages Must be touched by finger, gloved hand, or soft-tip stylus. Something hard like a pen won't work Not completely sealable, can be affected by large amounts of dirt, dust, and / or water in the environment. Capacitive A capacitive touch screen consists of a glass panel with a capacitive (charge storing) material coating its surface Circuits located at corners of the screen measure the capacitance of a person touching the overlay. Frequency changes are measured to determine the X and Y coordinates of the touch event They are used in a wide range of applications

Touchscreens Capacitive Advantages High touch resolution High Clarity Not affected by dirt, grease, moisture. Disadvantages Must be touched by finger- will not work with any non-conductive input Resistive Consists of a glass or acrylic panel that is coated with electrically conductive and resistive layers. The thin layers are separated by invisible separator dots.

Touchscreens Resistive Advantages The thin layers are separated by invisible separator dots Generally the most affordable Advantages High touch resolution Works with any stylus Not affected by dirt, dust, water, or light Disadvantages 75 % clarity Resistive layers can be damaged by a sharp object