1. Technical Field
The present invention relates to electro-optic apparatuses in which an electro-optic material is held between a pair of substrates, and electronic units using the electro-optic apparatuses.
2. Related Art
Among various electro-optic apparatuses, electro-optic apparatuses using liquid crystal as an electro-optic material include a first substrate, a second substrate attached to the first substrate with a predetermined gap disposed therebetween by a sealing member, and an electro-optic-material layer held in an area partitioned by the sealing member within the gap, and first transparent driving electrodes and second transparent driving electrodes formed on the first substrate and the second substrate, respectively, apply an electric field to the electro-optic-material layer.
In such an electro-optic apparatus, when a back-light apparatus is disposed at the rear surface side of the first substrate, optical modulation is applied to light emitted from the back-light apparatus while the light passes through the electro-optic-material layer, to display a predetermined image in transmission mode. When an optical reflection film is formed at a lower layer side of the first driving electrodes at the first substrate, since optical modulation can be applied during the period in which external light incident from the second substrate side is reflected by the optical reflection film and output from the second substrate, an image can be displayed in reflection mode.
In transflective electro-optic apparatuses, light transmission holes are formed in an optical reflection film formed at a lower-layer side of first driving electrodes, and a back-light apparatus is disposed at the rear-surface side of a first substrate. Transmission-mode display is performed at an area where the light transmission holes are formed, and reflection-mode display is performed at an area where the light transmission holes are not formed.
In addition, when a color filter is formed in a second substrate at a zone which covers an area where the first driving electrodes face second driving electrodes, a color image can be displayed.
To perform such display operations, predetermined signals need to be sent to the first driving electrodes and the second driving electrodes. To this end, a driving IC needs to be mounted on each of the first substrate and the second substrate, or a flexible substrate on which a driving IC is mounted needs to be mounted on each of the first substrate and the second substrate. With this structure, since two driving ICs are required, and in addition, a mounting region extending over the other substrate needs to be obtained for each of the first substrate and the second substrate, a wide region is required at an outer side of an image area of the electro-optic apparatus.
Therefore, a structure has been employed in which mounting terminals formed at an extending region over the second substrate, first inter-substrate electrical-connection terminals formed at an area where the first substrate and the second substrate overlap, first wiring patterns for connecting mounting terminals to the first driving electrodes, and second wiring patterns for connecting mounting terminals to the first inter-substrate electrical-connection terminals are provided for the first substrate, and second inter-substrate electrical-connection terminals facing the first inter-substrate electrical-connection terminals are provided for the second substrate.
In the first substrate, conventionally, transparent electrically conductive films, such as an ITO film which forms the first driving electrodes, are used for the mounting terminals, the first inter-substrate electrical-connection terminals, the first wiring patterns for connecting mounting terminals to the first driving electrodes, and the second wiring patterns for connecting mounting terminals to the first inter-substrate electrical-connection terminals.
In the first substrate, however, when the second wiring patterns, which are long and extend from mounting terminals to the first inter-substrate electrical-connection terminals, are made from only the ITO film which forms a transparent electrically-conductive film constituting the first driving electrodes, the electrical resistance thereof becomes very large.
When a color filter layer is formed at the second substrate in transflective electro-optic apparatuses, since the color filter layer is formed at a flat area, the thickness of the color filter layer is the same between the transmission display area where light transmission holes are formed and the reflection display area where the light transmission holes are not formed. Therefore, a problem occurs in display color images, in which reflection-mode colors are deep whereas transmission-mode colors are light. This is because transmission display light passes through the color filter layer only once whereas reflection display light passes the color filter layer twice, once at input and once at output.
The present invention has been made in consideration of the above situations. An object of the present invention is to provide an electro-optic apparatus using inter-substrate electrical connections, and an electronic unit using the electro-optic apparatus both of which have reduced wiring resistance and have a structure that can solve the problem in which reflection-mode colors are deep whereas transmission-mode colors are light in images displayed in both transmission mode and reflection mode.