Reflective display using multiple liquid crystal layers for controlable reflection

A display device comprising a composite multi-layer film in which films and liquid crystal layers are alternately laminated, a voltage being applied to said composite multi-layer film to control the reflection factor of said composite multi-layer film, characterized in that a refractive factor n.sub.LC1(.lambda.n), in a major axis direction, and a refractive factor n.sub.LC2(.lambda.n), in a minor axis direction, of a liquid crystal used in said liquid crystal layers with respect to light having a predetermined wavelength (.lambda.n) and a refractive factor n.sub.F1(.lambda.n) and a refractive factor n.sub.F2(.lambda.n), in X- and Y-axis directions which are perpendicular to each other in the film surface, of said films with respect to light having the predetermined wavelength (.lambda.n) are set in at least one of combinations of films and liquid crystal layers, which are adjacent to each other, of said films and said liquid crystal layers of said composite multi-layer film, to satisfy the following conditions [1] and [2]:

• [1] n.sub.LC1(.lambda.n) .gtoreq.n.sub.F1(.lambda.n), or n.sub.LC1(.lambda.n) .apprxeq.n.sub.F1(.lambda.n), and
• [2] n.sub.LC2(.lambda.n) .apprxeq.n.sub.F2(.lambda.n), or n.sub.LC1(.lambda.n) >n.sub.LC2(.lambda.n), n.sub.F1(.lambda.n) >n.sub.F2(.lambda.n)
• wherein the n.sub.F1(.lambda.n), n.sub.LC2(.lambda.n), a thickness d.sub.LC of said liquid crystal layer, and a thickness d.sub.F of said film are set in at least one of the combinations of films and liquid crystal layers, which are adjacent to each other, to satisfy at least one of the following conditions [3] and [4]:
• [3]n.sub.F1(.lambda.n) .multidot.d.sub.F .apprxeq.(1/4+k/2).multidot..lambda.n, and
• [4]n.sub.LC2(.lambda.n) .multidot.d.sub.LC .ltoreq.(1/4+m/2).multidot..lambda.n, or n.sub.LC2(.lambda.n) .multidot.d.sub.LC .apprxeq.(1/4+m/2).multidot..lambda.n
• (where k and m are 0 or integers).

A display device comprising a composite multi-layer film in which films and liquid crystal layers are alternately laminated, a voltage being applied to said composite multi-layer film to control the reflection factor of said composite multi-layer film,

• characterized in that a refractive factor n.sub.LC1(.lambda.n), in a major axis direction, and a refractive factor n.sub.LC2(.lambda.n), in a minor axis direction, of a liquid crystal used in said liquid crystal layers with respect to light having a predetermined wavelength (.lambda.n) and a refractive factor n.sub.F1(.lambda.n) and a refractive factor n.sub.F2(.lambda.n), in X- and Y-axis directions which are perpendicular to each other in the film surface, of said films with respect to light having the predetermined wavelength (.lambda.n) are set in at least one of combinations of films and liquid crystal layers, which are adjacent to each other, of said films and said liquid crystal layers of said composite multi-layer film, to satisfy the following conditions [15] and [16]:
• [15] n.sub.F1(.lambda.n) .gtoreq.n.sub.LC2(.lambda.n), or n.sub.F1(.lambda.n) .apprxeq.n.sub.LC2(.lambda.n), and
• [16] n.sub.LC2(.lambda.n) .apprxeq.n.sub.F2(.lambda.n), and n.sub.LC1(.lambda.n) >n.sub.LC2(.lambda.n)
• wherein the n.sub.F1(.lambda.n), n.sub.LC1(.lambda.n), a thickness d.sub.LC of said liquid crystal layer, and a thickness d.sub.F of said film are set in at least one of the combinations of films and liquid crystal layers, which are adjacent to each other, to satisfy at least one of the following conditions [17] and [18]:
• [17] n.sub.F1(.lambda.n) .multidot.d.sub.F .apprxeq.(1/4+k/2).multidot..lambda.n, and
• [18] n.sub.LC1(.lambda.n) .multidot.d.sub.LC .gtoreq.(1/4+m/2).multidot..lambda.n, or n.sub.LC1(.lambda.n) .multidot.d.sub.LC .apprxeq.(1/4+m/2).multidot..lambda.n
• (where m is 0 or an integer).