A diffuser for backlighting a display panel consists of a shell having a flat surface for positioning against the backside of the panel. The shell has a cavity with two sections. A reflection cavity section extending into the shell from the flat surface has highly reflective walls one of which opposite the mouth of the cavity defines a ramp. An illumination cavity section extending into the shell intercepts the reflection cavity section at a boundary near the foot of the ramp. When light propagates from the illumination cavity section into the reflection cavity section, the walls of the latter cavity section distribute that light by reflection and the ramp redirects that light to the mouth of the reflection cavity section from which the light propagates to the display panel as a uniform diffuse emanation.

A radio paging receiver enables an user of the receiver later to see a received message even when an alert stopping operation or message confirmation operation is first executed in an environment too dark to see the received message. The receiver has a photosensor for detecting whether a display environment is light or dark. If the alert stopping operation is executed in the dark condition, the received message is stored in a memory as an unconfirmed message, so that the user later can see and read the received message in a light condition after a change of the environment. In addition, when the environment is changed from a dark condition to a light condition, if an unconfirmed message exists in the memory, the receiver alerts the user.

A display control device for receiving input data at a display controller-kernel unit, storing it in a memory, sequentially reading the stored data from the memory and displaying it on a display unit. The control device comprises a counter which is reset when a signal indicating writing of data in the memory is detected to output a counter signal when a predetermined value is counted, a display control circuit for outputting a control signal so as to close a gate inserted in a signal line between the display controller-kernel unit and the display unit in response to the counter signal to interrupt the signal line and turn off the backlight of the display unit, and means for invalidating the control signal when the fact that a signal is written in the memory is detected.

An electronic mail sensor for informing a user when something has been put into a mailbox includes a door coupled to a mailbox for selectively covering an open end of the mailbox. A transmitter assembly is coupled to the mailbox adjacent the open end and includes a sensor for detecting when the door is in an open position. The transmitter assembly further includes a transmitter operationally coupled to the sensor for transmitting a signal when the door is in an open position. A receiver assembly includes a receiver for receiving the signal, the receiver assembly includes a mail indicating light operationally coupled to the receiver such that the mail indicating light is illuminated upon the receiver receiving the signal.

A pager having a notifier to notify the receipt of a call signal for itself, an LCD to display certain display messages, a light sensor to detect the light quantity of the light irradiated to the surface of the LCD, a control section to generate the contrast adjustment signal corresponding to the received light quantity of the LCD detected by the light sensor, a reference voltage generation section to generate the reference voltage according to the contrast adjustment signal generated by the control section, and an LCD driver to adjust the light intensity of the display message on the LCD according to the reference voltage supplied from the reference voltage generation section.