NBSIR 77-1393 (FTC)

The Effects of Home Video

Games on Television Receivers

Kenneth W Yee

Owen B. Laug

Institute for Applied Technology

Center for Consumer Product Technology

National Bureau of Standards

Washington, D.C. 20234

October 1 977

Final

Prepared for Federal Trade Commission

Bureau of Consumer Protection

Division of Compliance

Washington, D.C.

NBSIR 77-1393 (FTC)

THE EFFECTS OF HOME VIDEO

GAMES ON TELEVISION RECEIVERS

Kenneth W. Yee

Owen B. Laug

Institute for Applied Technology

Center for Consumer Product Technology

National Bureau of Standards

Washington, D C. 20234

October 1977

Final

Prepared for Federal Trade Commission

Bureau of Consumer Protection

Division of Compliance

Washington, DC.

U.S. DEPARTMENT OF COMMERCE, Juanita M. Kreps'Secretary

Dr. Sidney Harman, Under Secretary

Jordan J. Baruch, Assistant Secretary for Science and Technology

NATIONAL BUREAU OF STANDARDS. Ernest Ambler, Acting Director

Preface

This report describes the results of a short investigation on the

effects of home video games on television receivers for the Federal Trade

Commission. The length of the study and the funding level did not allow

an indepth investigation. As a result, the number of games and number

of television receivers tested is limited. As noted under "Significance

of Laboratory Evaluations" only one game and one receiver were used for

any particular test. Effects of interactions of the various games, receivers,

and factors examined were not determined. Visual rather than optical

measurements have been used. The purpose of the study was to determine

if a potential problem exists in terms of video games producing objectionable

permanent patterns on television receiver screens and was not intended to

fully define any problem that exists or determine all possible actions that

would reduce such a problem.

Introduction

This report describes the results of a brief analysis on the potential

problem of video games, some of which have been known to produce a

permanent pattern on the screen of television receivers. A laboratory

evaluation was made to put in perspective the primary factors which appear

to affect the problem.

A review of the data subpoened by the Federal Trade Commission from

manufacturers of TV receivers, games, and picture tubes shows that the

majority of complaints have come from dealers who have displayed the games

on receivers for extended periods. The primary complaint has been an

objectionable pattern which is permanently burned into the screen of the

receiver. The stationary pattern formed by the outline of the game is most

noticeable when the set is turned off and often is visible during regular

broadcast reception. The pattern imprinted on the screen was judged by

many dealers to be so objectionable that the set could not be sold. On the

otherhand, there have been extremely few consumer complaints of this

problem when the game is used intermittently in the normal manner. The

only explanation is that these early games did not get used for a

sufficient number of hours to develop an objectionable pattern.

Information is not available on the typical range of hours per year of

video gane use by consumers.
2

As further evidence that the problem of browning is not being

experienced by consumers is that a major television manufacturer has

inspected over 300,000 picture tubes returned for rebuilding . There has

not been a single report of a tube which has any patterns on the face.

This company has spent considerable time and effort in trying to define the

problem and the fundamental causes by performing their own tests and

setting up task forces. In general their tests have shown that

discoloration can occur in about 20 hours of continual use. Monochrome

(black and white) tubes apparently discolor about twice as much as color

tubes and that after about 150 hours of continual use for monochrome tubes

a saturation level is achieved, that is, continued use will not cause

significant further browning. Also they have observed that in sane cases

the browning would diminish by itself from exposure to ambient light and

normal use with program material. The disappearing phenomenon is

apparently not completely well understood. Tests at a glass manufacturer

have shown that the visible pattern on the screens of tubes is due to what

is called x-ray browning of the glass. The glass manufacturer and a

television receiver manufacturer have shown that light exposure and/or

baking can cause the discoloration to disappear.

Some game manufacturers have recognized the potential problem and have

modified their games either by reducing the peak-white modulation level or

devising more sophisticated techniques. On the otherhand, some game

manufacturers have not admitted to problems despite tests with their games
3

by others which have shown them to produce permanent patterns on TV

receiver screens.

Games Examined

A total of nine different manufactured games were acquired for

exanination and test in the laboratory. The games selected ranged from the

inexpensive simple ball and paddle types to the new programmable types

which offer a wide variety of games by means of removable cartridges.

Also, the selection of some of the games was based on those which have been

tested and reported by others to cause objectionable patterns.

The modulation levels of each of the games was measured with an

oscilloscope. Table 1 lists each of the games and the measured levels of

modulation for the peak white and the black level signal referenced to the

sync-peak amplitude.^- In this report games referred to as high modulation

games means that the peak-white anplitude is between 10 and 24 percent.

Reduced modulation games are those with a peak-white amplitude in the range

of 25 to 50 percent.

Laboratory Evaluations

Four different laboratory experiments were performed. In the first

three, games with different modulation or operating cycles were each

The American system for modulation of television signals is negative

amplitude modulation, that is, increasing light produces a decrease in

carrier amplitude. The sync-peak amplitude represents the maximum peak

power capability of the signal and therefore is referenced at 100%. The

standard for black level amplitude is 75% and the peak-white amplitude is

15%.
4

connected to four television receivers; two color and two monochrome

receivers f one of each pair at normal brightness control setting and one at

the highest useable brightness control setting. The fourth game was

connected only to a monochrome receiver at high brightness which had been

found to be the worst case test (shortest time for a visible pattern).

The first three experiments were designed to provide comparisons of

three factors reported to affect the operating time for patterns to develop

or the severity of pattern that might occur in a given amount of operating

time

The three comparisons are as follows:

1. The effect of high vs normal receiver brightness

control settings.

2. The effect of continuous game operation vs game

operation interspersed with broadcast program reception.

3. The effect of a high modulation game signal vs a reduced

modulation game signal.

The 4th experiment evaluates a unique technique used in game D which

continuously varies the luminance (brightness) and color of the game
5

pattern if the game is left on but is not being played. Each experiment

will be discussed separately. All laboratory evaluations were judged

visually by the same observer across all of the experiments using the

rating scale and criteria shown in Table Quantitative optical

measurements have been made by one TV receiver manufacturer but the time

and funding of this evaluation did not allow this sophistication. The

experimenters opinion of the possible user reaction to each level is given.

Based on the assumption that these reactions are correct, the critical

level which would result in significant consumer dissatisfaction is level

The operating time for any visible pattern to reach this level has been

used as the basis for comparison of the factors which may affect pattern

development time or severity.

High vs Normal Receiver Brightness

The results of the comparison of high vs normal TV receiver brightness

control settings are shown in Table 3 . The table shows the operating hours

to reach a level 3 pattern for one color and three monochrome receivers

which were used with three different games. Note that in most cases

operating the receiver at high brightness control Table 4 game C settings

decreases the operating hours to reach a given pattern level. The practice

should be discouraged since for some games a level 3 pattern will occur on

monochrome receivers in about 100 hours of game use. Since for some games,

level 3 patterns occur in a few hundred hours of use even at normal
6

brightness settings, receiver control adjustment alone will not eliminate

consumer complaints.

Fig. 1 is a photograph of the screens of tuo monochrome receivers

displaying the fixed pattern produced by game B. The upper screen is on

che set that has the brightness control set to a high level. The lower

screen displays a normal brightness setting. Fig. 2 shows the resultant

pattern left on each of the receiver screens after approximately 280 hours

of game time. As mentioned previously and it can be noted in Fig. 2 the

severity level of the retained pattern for a given number of hours is

always somewhat greater with the set adjusted for high brightness.

Comparison of Cycle vs Continuous Game Operation

Game B was operated on a cycled basis,, The receivers displayed the

game outline for 2 hours and then broadcast prograns for 4 hours. This

cycle continued 24 hours a day. The cycle is intended to more closely

simulate the use of a TV receiver and game in the home. The receiver was

not turned off during the cycle because a limited time was available to

accumulate enough game operating hours. Game C was displayed continuously.

The test was designed to verify reports that the game hours to result in

any pattern in normal intermittent use is much longer than the hours of

continuous game operation which results in the same pattern level.
7

The results of this comparison are shown in Table 4 for the game B

which was cycled and game C which was operated continuously. Both are high

modulation games; the possible differences between the games should be

examined in Table 3. Comparable pattern levels for continuous and cycled

games occured only on the monochrome receivers. For the high brightness

receivers there is no significant difference in the hours at all. There

appears to be a difference in the hours of somewhat less than two to one

for the normal brightness setting receivers. For repeated intermittent

game use periods, separated by hours or probably days, there does not

appear to be a large difference in the nunber of operating hours required

to develop a given pattern level as compared with continuous use. The

pattern development is approximately proportional to gane hours regardless

of how they are accumulated. In other words if patterns occur in

continuous operation in a nunber of operating hours that the game is likely

to be used, it appears that the same severity of pattern is likely to

eventually occur in normal use after a similar number of operating hours.

Figure 3 shows a card game format produced by one of the cartridges

supplied with game C on a 19-inch monochrome receiver. The image remains

stationary if the game is not played. Although portions of the format are

in color if used with a color receiver, the score numbers at the top are

white on a black background at maximum modulation. Figure 4 shows the

screen of the same set turned off after about 430 hours of continuous game

operation. However, as shown in Table 6 a level of 3 was achieved in less
8

than 100 hours, when used with a monochrome receiver. The degree of

severity shown here would doubtless be judged by most to be highly

objectionable. It is interesting to note that the manufacturer of this

particular game in response to specification five of the FTC subpoena

reported that no burns of any nature were observed in any of their tests

and so has concluded that there is no problem.

Comparison of High Modulation vs Reduced Modulation Game Signals

A game design technique that has been adopted by several manufacturers

to increase the operating hours before any pattern developes is to reduce*

the maximum modulation level of the game signal. The effect on the picture

is to reduce the brightness and contrast of the picture from the maximum

attainable for any given receiver control settings. If the receiver

controls are adjusted for a normal picture on a broadcast program as

usually recommended in the game instruction book and then switched to the

gane, the game picture will have low brightness whites or light colors and

grey rather than true black tones.

Game B is a high modulation game capable of the maximixn white level

defined by TV broadcast standards. Game A is a reduced modulation game

with a white level typical of reduced modulation games. Both were operated

on the cycle of 2 hours game and 4 hours broadcast program previously

described. The results of this comparison are shown in Table 5. None of

In Table 1, games B and C are high modulation games. All others have

reduced modulation.
9

the 4 color-receivers connected to these games reached level 3 and are not

included in the table. On the high brightness monochrome receivers, the

reduced modulation game required 3 times the operating time to reach level

3 . For the normal brightness monochrome receivers, the reduced modulation

game accumulated twice the hours at which the high modulation game reached

level 3 without reaching that level. This time corresponds to one hour a

day for a year. This seems like a large nunber of game playing hours but

would be accumulated in 2 weeks of continuous operation if a game and

receiver were left on.

Evaluation of Variable Luminance Levels

Of the games evaluated in the laboratory, only game D had a unique

design feature which was judged to be intended to prevent any pattern on

the tube even after prolonged operation. . The playing time of any game ends

after about 2-1/4 minutes or if a player scores 100 points. The game then

leaves the final picture on the screen but continuously switches the

luninance (brightness) and the color of each element in the picture. This

technique subjects all parts of the screen to about the same average

luminance over a long period of time. This results in an overall browning

of the tube face glass similar to what normally occurs in viewing broadcast

programs.
10

This game was connected only to a monochrome receiver with high

brightness settings which is the worst case, a condition which will produce

any pattern in the shortest time. The results of this test are shown in

the right hand column of Table 6.

Game D would not have caused any visible pattern except for the fact

that the rectangular playing area did not cover the entire face of the

tube. This effect is intentional in the design and prevents parts of the

game picture fran being off the edges of the screen on some receivers. On

the monochrome receiver used in the test, and several others, this game has

a blank band at the top and left edge of the tube. A faint outline of the

playing rectangle is visible at these locations. The pattern was still

judged to be a level 2 after over 400 hours of operation. However, it

probably would not be seen by most observers.

Significance of Laboratory Evaluations

The results of all tests are shown in Table 6 for the 4 games and 13 TV

receivers operated in the laboratory. Since only one game and one receiver

for any particular control setting or operating cycle used, the results

should only be considered trends and not representative of what will result

for any individual game, receiver or user. Additionally, the color

receivers and monochrome receivers were not all the same model but each

pair used for normal and high brightness settings were the same model.
11

Operating time differences of less than 10 hours for the cycled games and

30 hours for the continuously operated games are not significant due to

observation gaps during weekends when rating changes may have occured.

Conclusions

It is obvious from these tests that eventually most electronic video

games can produce some level of a permanent pattern on the screens of most

television receivers. These results could be achieved in various ways by

users failing to turn the game or television receiver off at the end of

game play. One can envision several possible habits of users which could

result in a large number of accumulated game hours. For instance several

hours could accumulate regularly if children leave the room to go out to

play without turning the game off or leave the game and television receiver

on all night. The worst condition that could occur would be if the game

and receiver were inadvertently left on while on vacation. Even the

reduced modulation games would cause an objectionable pattern on a

monochrome receiver in two weeks of continuous operation. Because of the

above possibilities some additional measure is necessary to prevent pattern

development if the game or receiver is not turned off after play. The

technique of varying the luminance levels over the entire screen after play

which was previously described in the evaluation of variable luminance

levels is an effective one. Another technique reported by one manufacturer

is that after 90 seconds of inactivity the game will switch the signal to
12

produce a blank screen on the receiver. This game was not examined in the

laboratory but the technique would certainly be effective. There may be

other design techniques which could be incorporated in new game designs.

All video games examined in the laboratory were found to cause some

'

degree of visible, but not necessarily objectionable, pattern on the

screen of monochrome television receivers within one to two-hundred hours

of game use. Color television receivers are less susceptable so that only

games with high signal modulation will cause some degree of a visible

pattern on the screen in a similar nunber of hours of game use.

There are many factors which affect the ultimate severity and time for

a pattern to become visible. The primary factors which were shown to have

the greatest effect are:

1. type of receiver, color or monochrome

2. the signal modulation level of the game

3. the brightness and contrast settings on the receiver.

Limited testing indicates that the degree of pattern development is

approximately proportional to the total accumulated game operating hours
13

regardless of whether the use is continuous or interspersed with normal

broadcast reception.

Reducing the modulation level of the game signal is an effective way of

extending the nunber of operating hours before any given level of pattern

develops. Games with a reduced level of modulation produced no objectional

pattern on any receiver in over 300 hours of game use and no visible

pattern was observed on color receivers in the same number of hours of game

use. However, games with high levels of modulation were found to produce

objectional patterns on the screens of monochrome receivers in about 100

hours of game use.

Many high modulation games have been sold in the last two years but

there have been few consumer complaints. This indicates that these games

probably did not get used for the 100 to 200 hours which is sufficient to

develop objectionable patterns. Since reduced modulation extends this

time, it is unlikely any objectionable pattern will occur due to actual

gane playing time. There is some concern that the new programmable games

may encourage more playing hours because of the diversity of games

available. It still seems unlikely that any one game out of the many

available cartridges would be played more than the earlier nonprogrammable

games. The game cartridges should be designed, however, to avoid common

stationary picture elements between different games.
14

The greatest danger of producing objectionable patterns on the screen

of a television receiver will be caused by the users’ failure to turn the

game and/or the receiver off after play has ended. The only certain

technique to prevent this is in the game design. One technique which has

been described is that after a short interval of inactivity the game will

switch the signal to produce a blank screen. Another technique is to

automatically switch to a non-pattern producing mode after a period of

inactivity. At present these techniques are the only known way to make the

games fool proof. Because of the possibility of a large number of

accumulated game hours, it is recommended that game manufacturers provide a

warning regarding prolonged display of a non-moving pattern and the

ultimate consequences. Games which can demonstrate no problem under the

worst case might be exempt fran such a disclosure.
TABLE I

Measured Modulation Levels of Each of Various Games

Game Description Modulation

Peak-White

%

Black

A Color - A variations of

ball & paddle

A1 69

B Monochrome - Ball & paddle 13 75

C Color - Ball & paddle plus

programmable cartridges

10 71

D Color - Programmable Cartridges 3A 75

E Monochrome - 5 games plus cartridges 50 88

F Monochrome - A variations of

ball & paddle

28 63

G Color - A variation of

ball & paddle

38 63

H Color - programmable cartridges 25 63

I Color - 8 variations of 25 50

ball & paddle
Table 2

A Visual Rating Scale

Receiver

Level Power Criteria

0 OFF No pattern visable on close

inspection with bright light

.

1 OFF Some pattern visable on close

inspection with bright light.

Pattern outline not definable.

2 OFF Faint pattern visable on close

inspection with bright light.

Outline definable.

3 OFF Visable pattern on inspection

in normal room light.

4 OFF Obvious pattern visable in

any light.

5 ON Faint pattern visable depending

on program scene.

6 ON Visable pattern on many

broadcast program scenes.

Possible User Reaction

None

None

Might be noticed by a critical user in bright

room light. Probably

would not be seen by most

users in normal room light

Would be noticed by most

users

.

Would be seen by all users

Would be noticed by many

viewers particularly on stationary uniform color

patterns or on fades

between scenes.

Would be noticed by most

users

.
Table 3

Comparison of High vs Normal

Receiver Brightness Settings

Hours to reach level 3

Game

A

B

C

Receiver

Setting

Color

High Normal

240 430

Monochrome

High Normal

310 330

1

105 170

2 240 ^352

Rating had not been reached at this number of operating

hours

- Reached level 4 at this number of operating hours.
Table 4

Comparison, of Cycle vs Continuous

Operating Time

Hours to reach level 3

Game B

Cycle Operation

Game C

Continuous Operation

Monochrome

High Brightness 105 95

Monochrome

Normal 170 95

Brightness

>

Note: Color receivers did not reach

level 3 on game B.

No comparison is possible.

\
Table 5

Comparison of High Modulation

vs Reduced Modulation of

Game

Hours to Reach Level 3 Rating

^''\

v Game

Receiver

High Modulation ! Reduced Modulation

Game B j Game A

Monochrome

High Brightness

; 105 310

Monochrome

Normal Brightness

t 170 j 330

1

i

i

i

i

^Rating had not been reached at this number of operating hours

Mote: Color receivers did not reach level 3

No comparison is possible.
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