Device for driving a display element having a memorizing property
First Claim
1. A device for controlling an electro-optical display element of the type which is capable of storing charge, the display element being in a colored state upon the application thereto of a first polarity voltage for storing a first quantity of charge and being in a colorless state upon the application thereto of an opposite polarity voltage for storing a second quantity of charge, the display element remaining in said states for predetermined periods of time after removal of said voltages, comprising means for detecting the quantity of charge stored in the display element, the detecting means including a first detecting circuit for producing a first signal when the quantity of charge stored differs from a first predetermined range of values required for the display element to be in the colored state, and a second detecting circuit for producing a second signal when the quantity of charge stored differs from a second predetermined range of values required for the display element to be in the colorless state, and drive means for applying said voltages to the display element, the drive means including a first driving circuit for applying the first polarity voltage to the display element in response to the first signal and to the occurrence of a display command signal, and a second driving circuit for applying said other polarity voltage to the display element in response to the second signal and to the non-occurrence of the display command signal.
1 Assignment
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Accused Products
Abstract
In a device for driving an electro-optical display element having a memorizing property and which produces color upon the application of a first polarity voltage thereto and loses color upon application thereto of a voltage of opposite polarity the coloration and the color-extinction taking place in response to a display command signal applied as an input to the device, there is provided means for detecting the quantity of charge stored in the display element and for generating a detection signal when the detected value of stored charge is beyond a predetermined range, means for continuously generating a pulse signal, and drive means having switch means adapted to be closed in synchronism with the pulse signal when the display command signal and the detection signal are applied as inputs, the drive means applying a voltage to the display element upon closing of the switch means.
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Citations
8 Claims
- 1. A device for controlling an electro-optical display element of the type which is capable of storing charge, the display element being in a colored state upon the application thereto of a first polarity voltage for storing a first quantity of charge and being in a colorless state upon the application thereto of an opposite polarity voltage for storing a second quantity of charge, the display element remaining in said states for predetermined periods of time after removal of said voltages, comprising means for detecting the quantity of charge stored in the display element, the detecting means including a first detecting circuit for producing a first signal when the quantity of charge stored differs from a first predetermined range of values required for the display element to be in the colored state, and a second detecting circuit for producing a second signal when the quantity of charge stored differs from a second predetermined range of values required for the display element to be in the colorless state, and drive means for applying said voltages to the display element, the drive means including a first driving circuit for applying the first polarity voltage to the display element in response to the first signal and to the occurrence of a display command signal, and a second driving circuit for applying said other polarity voltage to the display element in response to the second signal and to the non-occurrence of the display command signal.
Specification