Characteristic parameter and measurement of projection screens
1 Scope
This standard specifies the characteristic parameters and measurement of reflective and transmitting projection screens.
This standard is applicable to reflective and transmitting screens for film, slide, projection and video projection, and is not applicable to other special screens.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this standard. For dated references, subsequent amendments (excluding corrections) to, or revisions of, any of these publications do not apply to this standard. However parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies.
JB/T 6839 The classification of projection screens
3 Terms and definitions
For the purposes of this standard, the following terms and definitions apply.
3.1
projection screens
light reflecting and transmitting screens with specified optical characteristics for projection
3.2
type D screen
a type of screen, also known as diffuse reflective screen, which diffuses incident light in the space of 2π solid angle, with a polar coordinate characteristic curve of luminance factor approximate to an ideal diffuse reflection semicircle
3.3
type B screen
a type of screen, also known as gain reflective screen at incident angle, by which the reflection of the incident light is characterized by a collective gain reflection at the incident angle of light in the space of 2π solid angle
3.4
type S screen
a type of screen, also known as gain reflective screen at the angle of reflection, by which the reflection of the incident light is characterized by a collective gain reflection at the angle of reflection of light in the space of 2π solid angle, with an angle of reflection equal to the incident angle
3.5
type R screen
a type of screen, also known as transmitting screen, which is viewed with transmitted light with a collective gain direction consistent with the incident light direction
3.6
luminance factor β
as defined in JB/T 6839, Clause 2
3.7
effective scattering angle 2α
as defined in JB/T 6839, Clause 2
3.8
Complex index K
sum of allowable combinations of βindex and 2αindex for reflective or transmitting projection screens
Namely: K=βindex+2αindex
3.9
sound attenuation
sound attenuation, in case of perforated screens, caused by the loudspeaker being placed behind the screen, which is defined as the difference between the sound attenuation at 8kHz/12.5kHz and that at 500Hz, expressed in dB
Foreword III
1 Scope
2 Normative references
3 Terms and definitions
4 Characteristic parameters
4.1 Luminance factor β and βindex
4.2 Effective scattering angle 2α and 2αindex
4.3 Complex index K
4.4 Sound attenuation
5 Measurement of luminance factor β and effective scattering angle 2α of reflective screens
5.1 Test devices
5.2 Test conditions
5.3 Test procedures
5.4 Reflected luminance factor characteristic curve
6 Measurement of luminance factor β and effective scattering angle 2α of transmitting projection screens
6.1 Measuring devices
6.2 Measuring conditions
6.3 Measuring procedures
6.4 Transmitted luminance factor characteristic curve
7 Measurement of Complex index K
8 Measurement of sound attenuation (only applicable to perforated reflective screens)
8.1 Measuring devices
8.2 Test conditions
8.3 Test procedures
Annex A (Normative) Schematic diagrams for plotting luminance factor characteristic curves
Figure 1 Schematic diagram for measuring the luminance factor β of a reflective screen (in horizontal plane)
Figure 2 Schematic diagram for measuring the effective scattering angle 2α of a reflective screen (in horizontal plane)
Figure 3 Schematic diagram for measuring luminance factor β of a transmitting screen (in horizontal plane)
Figure 4 Schematic diagram for measuring the effective scattering angle 2α of a transmitting screen (in horizontal plane)
Figure 5 Schematic diagram for sound attenuation measuring installations
Figure A.1 Polar coordinate system
Figure A.2 Rectangular coordinate system
Table 1 β intervals for diffuse reflective screens
Table 2 β intervals for diffuse transmitting screens
Table 3 β intervals for gain reflective screens
Table 4 β intervals for gain transmitting screens
Table 5 2α and additional conditions for diffuse reflective screens
Table 6 2α intervals for diffuse transmitting screens
Table 7 2α intervals for gain reflective screens
Table 8 2α intervals for gain transmitting screens
