Control system and methods for multi-mode privacy display
A display apparatus comprises a display device capable of operating in a first mode and a second mode where an image remains visible in both the first mode and the second mode in an on-axis direction and a visibility of the image is reduced in an off-axis direction in the second mode. A control system is capable of selectively operating the display device in the first mode or the second mode and can selectively control luminance of the displayed image in the first mode based on a first function and to selectively control luminance of the displayed image in the second mode based on a second function. High image visibility can be provided for a public mode of operation while in privacy mode of operation a high visual security level may be obtained by means of controlling an image characteristic such as image luminance, contrast and white point.
1 . A display apparatus comprising:
a display device arranged to display an image and capable of operating in at least a first mode and a second mode, wherein the image remains visible in both the first mode and the second mode in an on-axis direction, and a visibility of the image is reduced in an off-axis direction in the second mode compared to the first mode; and
a control system arranged to control the display device, the control system being capable of selectively operating the display device in the first mode or the second mode, wherein the control system is arranged to selectively control luminance of the displayed image in the first mode based on a first function that relates a level of luminance to a detected level of ambient light and to selectively control luminance of the displayed image in the second mode based on a second function that relates a level of luminance to a detected level of ambient light in the second mode.
2 . The display apparatus of claim 1 , wherein the display apparatus is arranged to connect to a network and the control system is arranged to selectively operate the display device in the first mode or the second mode based on a characteristic associated with the network.
3 . The display apparatus of claim 1 , wherein the control system is arranged to selectively operate the display device in the first mode or the second mode based on an identity of a user.
4 . The display apparatus of claim 1 , wherein the control system is arranged to selectively operate the display device in the first mode or the second mode based on a detected location.
5 . The display apparatus of claim 1 , wherein the display apparatus is arranged to receive a user input and the control system is arranged to selectively operate the display device in the first mode or the second mode based on the received user input.
6 . The display apparatus of claim 1 , wherein the control system is arranged to selectively operate the display device in the first mode or the second mode based on the detected level of the ambient light.
7 . The display apparatus of claim 1 , wherein the control system is arranged to selectively control at least one of the luminance, a contrast, a white point, or spatial frequency of the displayed image to maintain a selected privacy level based on the detected level of the ambient light.
8 . The display apparatus of claim 1 , wherein the first function relates a higher level of luminance to a detected level of the ambient light than the second function.
9 . The display apparatus of claim 1 , wherein the second function maintains a relationship Y0/Iθ≥1 lux/nit, where Y0 is the maximum output luminance of the display apparatus and I0 is the detected ambient light level.
10 . The display apparatus of claim 1 , wherein the second function maintains a relationship Y0≤Y0 lim , where Y0 is the maximum output luminance of the display apparatus and Y0 lim is given by the equation:
Y
0
lim
=
R
θ
+
V
lim
*
K
θ
(
V
lim
-
1
)
*
P
θ
where V lim has a value of 10, Rθ is the reflected ambient illuminance at an observation angle θ of 45 degrees laterally and zero degrees in elevation from the normal to the display apparatus, Kθ is the display black state luminance at the observation angle, and Pθ is the relative luminance at the observation angle θ compared to the maximum display output luminance Y0.
11 . The display apparatus of claim 1 , wherein the display apparatus is arranged to receive a time data input and an ambient light sensor input, and the control system is arranged to selectively operate the display device in the first mode or the second mode based on the time data input and the ambient light sensor input to reduce light pollution generated by the display apparatus.
12 . The display apparatus of claim 1 , wherein the display apparatus is arranged to execute application software and the control system is arranged to selectively operate the display device in the first mode or the second mode based on the application software being executed.
13 . The display apparatus of claim 12 , wherein the display apparatus is arranged to execute the application software for displaying a document, and the control system is arranged to selectively operate the display device in the first mode or the second mode based on at least one of a content of the document or a metadata associated with the document.
14 . The display apparatus of claim 13 , wherein at least one of the content or the metadata includes a security status of a transfer protocol of the document, and the transfer protocol is one of Hypertext Transfer Protocol or Hypertext Transfer Protocol Secure.
15 . The display apparatus of claim 1 , wherein the first mode is a public mode of operation and the second mode is a privacy mode of operation.
16 . A display apparatus comprising:
a display device arranged to display an image and capable of operating in at least a first mode and a second mode, wherein the image remains visible in both the first mode and the second mode in an on-axis direction, and a visibility of the image is reduced in an off-axis direction in the second mode compared to the first mode; and
a control system arranged to control the display device, the control system being capable of selectively operating the display device in the first mode or the second mode, wherein the control system is arranged to selectively control a characteristic of the displayed image in the first mode based on a first function based on a detected level of ambient light and to selectively control a characteristic of the displayed image in the second mode based on a second function based on a detected level of ambient light.
17 . The display apparatus of claim 16 , wherein the first mode is a public mode of operation and the second mode is a privacy mode of operation.
18 . The display apparatus of claim 16 , wherein the control system is arranged to selectively operate the display device in the first mode or the second mode based on at least one of a characteristic associated with a network that the display apparatus is connected to, an identity of a user, a location of the display apparatus, or a received user input.
19 . The display apparatus of claim 16 , wherein the characteristic that is selectively controlled is at least one of a luminance, a contrast, a white point, or spatial frequency of the displayed image to maintain a selected privacy level based on the detected level of the ambient light.
20 . The display apparatus of claim 16 , wherein the first function relates a higher level of luminance to a detected level of the ambient light than the second function.