Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2000-03-14
2001-09-25
Wu, Xiao (Department: 2774)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S213000, C345S182000
Reexamination Certificate
active
06295045
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid crystal display control device which is used to reduce the storage capacity of a storage element required when an image formed from video signals transmitted from a personal computer or the like is displayed in an enlarged mode on a liquid crystal display device.
2. Description of the Related Art
A technique as disclosed in Japanese Laid-open Patent Application No. Hei-4-12393 has been known as a liquid crystal display control device for displaying video information from a personal computer or the like while enlarging the video information. In this technique, a video signal transmitted from a personal computer or the like is temporarily stored in a frame memory, and the stored data are read out at a timing which is compatible with a liquid crystal display operation. This technique will be described in detail with reference to
FIGS. 12 and 13
.
FIG. 12
is a block diagram showing a control circuit in a liquid crystal display device disclosed in Japanese Laid-open Patent Application No. Hei-4-12393. In
FIG. 12
, reference numeral
1101
represents a video signal from the personal computer or the like, and reference numeral
1102
represents a synchronous signal. Reference numeral
1103
represents a horizontal/vertical timing and basic clock generating circuit, reference numeral
1104
represents an automatic input signal discriminate circuit, reference numeral
1105
represents a frame memory data generating and frame memory write-in circuit, reference numeral
1106
represents a frame memory circuit which comprises a field memory and a line buffer, reference numeral
1107
represents a frame memory read-out and display data generating circuit, reference numeral
1108
represents an enlarged display control circuit, reference numeral
1109
represents a liquid crystal display circuit, and reference numeral
1110
represents a liquid crystal display unit.
FIG. 13
is a block diagram showing the details of the frame memory circuit
1106
shown in FIG.
12
. In
FIG. 13
, reference numeral
1201
represents a field memory, reference numeral
1202
represents a line buffer and reference numeral
1203
represents a read-out data select circuit.
In
FIGS. 12 and 13
, the horizontal/vertical timing and basic clock generating circuit
1103
generates a horizontal timing signal, a vertical timing signal and a basic clock signal CK
1
for controlling the operation of the frame memory data generating and frame memory write-in circuit
1105
on the basis of the horizontal and vertical synchronous signals
1102
for driving a CRT display device which are input from the personal computer or the like.
The frame memory data generating and frame memory write-in circuit
1105
generates a control signal WRCT (write clock signal SWCK, write enable signal WE, reset write signal RSTW) on the basis of the basic clock signal CK
1
, and outputs the control signal WRCT to the field memory
1201
(see FIG.
13
). Further, using the frame memory data generating and frame memory write-in circuit
1105
, memory data Din of one frame which are generated on the basis of the video signal
1101
input from the personal computer or the like are successively written and temporarily stored into the field memory
1201
.
Furthermore, the frame memory read-out and display data generating circuit
1107
generates a control signal RDCT on the basis of the clock signal CK
2
for driving the liquid crystal display, generated by the liquid crystal display circuit
1109
, and the control signal generated by the enlarged display control circuit
1108
, and then outputs the control signal RDCT to the frame memory circuit
1106
. The clock signal CK
2
for driving the liquid crystal display is set to have a longer period than the basic clock signal CK
1
.
The control signal RDCT comprises a read clock signal SRCK, a read reset signal RSTR, a write clock signal WCK, a reset write signal RSTWN, a read clock signal RCK, a reset read signal RSTRN and a data selection signal SELDT. Of these signals, the read clock signal SRCK and the read reset signal RSTR are supplied to the field memory
1201
. The write clock signal WCK, the reset write signal RSTWN, the read clock signal RCK and the reset read signal RSTRN are supplied to the line buffer
1202
of the frame memory circuit
1106
. The data selection signal SELDT are supplied to the read-out data select circuit
1203
of the frame memory
1106
.
The read-out select circuit
1203
selects any one of an output data D
1
of the field memory
1201
and an output data D
2
of the line buffer
1202
, and outputs the selected data as frame memory read-out data-Dout.
On the basis of the data-Dout, the frame memory read-out and display data generating circuit
1107
as described above generates serial liquid crystal display data which are compatible with the liquid crystal display unit
1110
.
On the basis of the clock signal CK
2
for driving the liquid crystal display, the liquid crystal display circuit
1109
generates a liquid crystal display driving signal, a data shift clock signal and an alternating signal which are compatible with the format of the liquid crystal display unit
1110
.
The liquid crystal display unit
1110
displays a predetermined image on the basis of the liquid crystal display data output from the frame memory read-out and display data generating circuit
1107
and the signal output from the liquid crystal display circuit
1109
.
The enlarged display control circuit
1108
judges whether an instruction for enlarging a part of the frame is made by an operator. If it is judged that the enlarge display instruction is made, it controls the frame memory data generating and frame memory write-in circuit
1105
and the frame memory read-out and display data generating circuit
1107
in accordance with information on an indicated magnification rate, an enlarging area, etc.
Further, the automatic input signal discriminate circuit
1104
discriminates, on the basis of the synchronous signal
1102
, an input video signal which is varied in accordance with, for example, the type of personal computer, and it controls the horizontal/vertical timing and basic clock generating circuit
1103
in accordance with the discrimination result.
According to the above-described technique, the enlargement processing can be performed. However, since the input and output operations of the video signals are perfectly asynchronously controlled by using a field memory, the field memory must have a storage capacity for storing video information of at least one frame. The memory capacity in which the video information of one frame can be stored is not so small in the present memory technique.
Furthermore, in the conventional technique as described above, all video signals are temporarily stored in the frame memory circuit
1106
so as to keep the read-out timing to the liquid crystal display unit constant at all times. Therefore, when a high-resolution video signal is input, a field memory to which high-speed access can be made is required irrespective of use and non-use of the enlargement processing. The use of a memory which can be accessed at high speed is a factor preventing cost reduction of the display device, because such a memory is expensive.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a liquid crystal display control device which performs enlargement processing while suppressing increase in memory capacity.
Another object of the present invention is to provide a liquid crystal display control device which enables application to high-resolution video signals irrespective of use of a memory having a low access speed (i.e., a cheap memory).
A further object of the present invention is to provide a liquid crystal display control device which can freely select any image quality and any cost in accordance with a user's request.
In order to attain the above objects, according to a first aspect of the present invention, a liquid crystal display control device
Furuhashi Tsutomu
Higa Atsuhiro
Kasai Naruhiko
Kurihara Hiroshi
Maeda Takeshi
Hitachi , Ltd.
Mattingly Stanger & Malur, P.C.
Wu Xiao
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