JP2013236148A - Transmission method and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the transfer amount of a signal without increasing the frequency of transmission clock when the signal is transmitted by a differential serial scheme.SOLUTION: A transmission method transmits a signal by a differential serial transmission scheme via a pair of transmission lines. The pair of transmission lines is composed of a positive side transmission line for transmitting a positive differential signal, and a negative side transmission line for transmitting a negative differential signal. The positive side transmission line and the negative side transmission line further transmit a common signal. The positive and negative differential signals are signals composed of the voltage with higher potential than the common signal by a voltage of Vs in a voltage level, and the voltage with lower potential than the common signal by the voltage of Vs. When the pair of transmission lines is called one lane of differential transmission lines, the whole of the transmission lines is composed of a plurality of lanes of differential transmission lines. The amplitude of the common signal transmitted by at least two lanes of differential transmission lines of the plurality of lanes is changed over time in synchronization with the positive and negative differential signals.

Description

  The present invention relates to a transmission method and a display device, and more particularly to a technique effective when applied to a display device in which an input signal is supplied in a differential serial transmission system via a pair of transmission lines.

A TFT liquid crystal display device using a thin film transistor as an active element can display a high-definition image, and is therefore used as a display device for a television, a personal computer display, or the like.
In general, in a liquid crystal display device, an area surrounded by two adjacent scanning lines (also referred to as gate lines) and two adjacent video lines (also referred to as source lines or drain lines) is separated from the scanning lines. A so-called sub-pixel is formed by forming a thin film transistor which is turned on by the scanning signal and a pixel electrode to which the video signal from the video line is supplied via the thin film transistor. A region where the plurality of sub-pixels are formed is a display region, and there is a peripheral region surrounding the display region. In the peripheral region, a drain driver (also referred to as a source driver) that supplies a video voltage (gradation voltage) to each video line and a gate driver that supplies a scanning voltage to each scanning line are provided.
A display control signal is input to the drain driver and the gate driver from a display control circuit (also referred to as a timing controller), and the drain driver and the gate driver are controlled and driven by the display control circuit. Note that display data or a display control signal from the main body side to the display control circuit is transmitted by a differential serial method as described in Patent Document 1 below.

JP-A-10-340070

In recent years, the transfer amount of image data per screen has increased with the increase in resolution of liquid crystal display panels, and it has become necessary to increase the transfer rate of display data or display control signals from the external main body to the display control circuit. Has been.
On the other hand, due to the internal layout on which the liquid crystal display panel is mounted, restrictions on the outer shape of the flexible wiring board become severe, and many wirings must be formed in a narrow width.
Under such circumstances, the wiring on the flexible wiring board is adopted from the RGB parallel wiring to the customer's request even though the high-speed serial wiring that supplies the input signal by the differential serial transmission method is adopted. A situation that is difficult to respond to occurs in the wiring layout design on the flexible wiring board.
In the differential serial transmission method, it is natural that if the transmission clock is increased, high-speed transmission is possible. However, this requires higher frequency transmission characteristics on the differential transmission line on the flexible wiring board. In other words, it is necessary to use a substrate (generally hard) with low high-frequency loss. This becomes a factor that limits the feature of the FPC that it can be folded and mounted.
The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to transfer a signal without increasing a transmission clock when transmitting a signal by a differential serial method. It is an object of the present invention to provide a transmission method and a display device adopting the transmission method.
The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

Of the inventions disclosed in this application, the outline of typical ones will be briefly described as follows.
(1) A transmission method for transmitting a signal by a differential serial transmission method via a pair of transmission lines, wherein the pair of transmission lines includes a positive transmission line that transmits a positive differential signal and a negative difference. A negative transmission line that transmits a signal, the positive transmission line and the negative transmission line further transmit a common signal, and the positive and negative differential signals have a voltage level of When the pair of transmission lines is referred to as a differential transmission line of one lane, the signal is composed of a voltage having a higher potential by Vs than the common signal and a voltage having a lower potential by Vs than the common signal. The entire transmission line is composed of a plurality of lane differential transmission lines, and the amplitude of the common signal transmitted by at least two lanes of the plurality of lanes is synchronized with the positive and negative differential signals. And change over time .
(2) In (1), the entire transmission line includes a differential transmission line of two lanes, and the first difference signal transmitted from the differential transmission line of the first lane in the differential transmission lines of the two lanes. 1st signal is reproduced from a differential signal transmitted through the differential transmission line of the second lane, and the primary extension composed of the differential transmission lines of the first and second lanes. The differential transmission line is regarded as the third differential transmission line, and the third signal is obtained from the difference signal of the third differential transmission path, which is the difference between the common signals transmitted through the first and second differential transmission lines. Play.

(3) In (1), the entire transmission line includes a differential transmission line of 4 lanes, and from the differential signal that transmits the differential transmission line of the first lane among the differential transmission lines of 4 lanes. The second signal from the differential signal that transmits the differential transmission line of the second lane, the third signal from the differential signal that transmits the differential transmission line of the third lane, the fourth signal A fourth signal is regenerated from the differential signal transmitted through the differential transmission line of the first lane, and a primary extended differential transmission line composed of the differential transmission lines of the first and second lanes is provided as the fifth signal. Considering a differential transmission line, a fifth signal from a differential signal of a fifth differential transmission line, which is a difference of a common signal transmitted through the first and second differential transmission lines, is converted into the third and fourth signals. Primary extended differential transmission line composed of differential transmission lines in the lane of the sixth differential transmission line The sixth signal from the differential signal of the sixth differential transmission line, which is the difference between the common signals transmitted through the third and fourth differential transmission lines, and the fifth and sixth primary signals. A secondary extended differential transmission line composed of extended differential transmission lines is regarded as a seventh differential transmission line, and a seventh difference which is a difference between the common signals transmitted through the fifth and sixth differential transmission lines. The seventh signal is reproduced from the differential signal of the differential transmission path.
(4) In (1), the transmission line is formed on a wiring board composed of a combination of an insulating base material and two or more conductive layers, and the transmission line on the positive side of each lane. And the negative transmission line are formed in the same conductive layer.
(5) In (4), the wiring board is a flexible wiring board.
(6) In (5), two conductive layers are formed on the wiring board.
(7) Moreover, this invention is a display apparatus which employ | adopted the transmission method in any one of (1) thru | or (6).

The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.
According to the present invention, when a signal is transmitted by the differential serial method, the amount of signal transfer can be improved without increasing the transmission clock.

It is a block diagram which shows schematic structure of the liquid crystal display device of the Example of this invention. It is the schematic which shows the signal waveform transmitted in the differential serial transmission system in the liquid crystal display device of the Example of this invention. It is a figure for demonstrating the differential serial transmission system in the liquid crystal display device of the Example of this invention. It is a figure for demonstrating the extended differential serial transmission system in the liquid crystal display device of the Example of this invention. It is the schematic which shows a part of signal waveform transmitted in the extended differential serial transmission system shown to Fig.4 (a). In the liquid crystal display device of the Example of this invention, it is sectional drawing showing the bending state of a flexible wiring board. It is a top view of the flexible wiring board of the liquid crystal display device of the Example of this invention. FIG. 7 is a cross-sectional view showing a cross-sectional structure taken along the line A-A ′ of FIG. 6. FIG. 8 is a sectional view showing a sectional structure when a shield layer is added to the sectional structure of FIG. 7. It is the schematic which shows the signal waveform transmitted in the conventional differential serial transmission system. It is a figure for demonstrating the conventional differential serial transmission system.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In all the drawings for explaining the embodiments, parts having the same functions are given the same reference numerals, and repeated explanation thereof is omitted. Also, the following examples are not intended to limit the interpretation of the scope of the claims of the present invention.
[Example]
FIG. 1 is a block diagram showing a schematic configuration of a liquid crystal display device according to an embodiment of the present invention.
In the liquid crystal display panel (PNL), a plurality of scanning lines (GL) and video lines (DL) are provided in parallel. Sub-pixels are provided corresponding to the intersections between the scanning lines (GL) and the video lines (DL).
The plurality of subpixels are arranged in a matrix, and each subpixel is provided with a pixel electrode (PX) and a thin film transistor (TFT). A counter electrode (CT) is provided so as to face each pixel electrode (PX), and a liquid crystal capacitor (LC) and a storage capacitor (Cadd) are provided between each pixel electrode (PX) and the counter electrode (CT). Is formed.
The liquid crystal display panel (PNL) includes a first glass substrate (SUB1) provided with a pixel electrode (PX), a thin film transistor (TFT), and a second glass substrate (not shown) on which a color filter and the like are formed. The two glass substrates are bonded together by a seal material provided in a frame shape in the vicinity of the peripheral edge between the two glass substrates while being overlapped with a predetermined gap therebetween, and both the liquid crystal sealing openings provided in a part of the seal material. Liquid crystal is sealed and sealed inside the sealing material between the substrates, and a polarizing plate is attached to the outside of both glass substrates.
Since the present invention is not related to the internal structure of the liquid crystal display panel, a detailed description of the internal structure of the liquid crystal display panel is omitted. Furthermore, the present invention can be applied to a liquid crystal display panel having any structure. For example, in the case of the vertical electric field method, the counter electrode (CT) is formed on the second glass substrate. In the case of the horizontal electric field method, the counter electrode (CT) is formed on the first glass substrate (SUB1).

FIG. 5 is a cross-sectional view showing a bent state of a flexible wiring board (FPC) in the liquid crystal display device according to the embodiment of the present invention.
FIG. 6 is a plan view of a flexible wiring board (FPC) of the liquid crystal display device according to the embodiment of the present invention.
FIG. 7 is a cross-sectional view showing a cross-sectional structure taken along the line AA ′ of FIG.
FIG. 8 is a cross-sectional view showing a cross-sectional structure when a shield layer is added to the cross-sectional structure of FIG.
5 and 6, SUB2 is the second glass substrate, 10 is the light guide plate, 11 is the lower frame, 12 is the crimping portion, and the flexible wiring board (FPC) is the first glass substrate (SUB1) in the crimping portion 12. ) And electrically and mechanically.
7 and 8, 20 is a base material layer, 21 is a ground layer to which a ground potential is applied, 22 is a wiring layer, 23 is a differential transmission line, 24 is a component, 25 is a shield layer, and 26 is an insulating layer. is there.
As shown in FIG. 5, in the liquid crystal display device of the present embodiment, the flexible wiring board (FPC) is bent and arranged on the back side of the liquid crystal display panel (PNL).
As shown in FIG. 7, the flexible printed circuit board (FPC) is formed on the base material layer 20, the ground layer 21 formed on the other surface of the base material layer, and one surface of the base material layer. It is composed of a differential transmission line 23 and a wiring layer 22 formed on both surfaces of the material layer, and a component 24 is mounted on a flexible wiring board (FPC).
In general, as shown in FIG. 7, the flexible wiring board (FPC) is a double-sided two-layer wiring at most. However, in recent years, as shown in FIG. In some cases, the shield layer 25 is formed to have four layers, but wiring cannot be formed in the shield layer 25, and the wiring layer is still two layers.

In the liquid crystal display device shown in FIG. 1, a drive circuit (DRV) is mounted on the first glass substrate (SUB1).
The drive circuit (DRV) includes a controller circuit 100, a drain driver 130 that drives the video line (DL) of the liquid crystal display panel (PNL), and a gate driver 140 that drives the scanning line (GL) of the liquid crystal display panel (PNL). A power supply circuit 120 that generates a power supply voltage necessary for displaying an image on a liquid crystal display panel (PNL), and a memory circuit 150.
Signals (display data and display control signals) are input to the controller circuit 100 from the external main body side via a transmission line (LEN) by a differential serial transmission method.
The controller circuit 100 controls the display by sending display data received by the differential serial transmission method to the source driver 130 and the memory circuit 150.

[Conventional differential serial transmission system]
First, a conventional differential serial transmission system will be described with reference to FIG. FIG. 9 is a schematic diagram showing signal waveforms transmitted in the conventional differential serial transmission method. 9A is a positive transmission signal (PS), FIG. 9B is a transmission signal, FIG. 9C is a common voltage (Vcom), and FIG. 9D is An inverted signal (/ S) of the signal (S) to be transmitted and FIG. 9 (e) is a negative-polarity transmission signal (NS).
As shown in FIG. 9, the signal to be transmitted (S) and the inverted signal (/ S) of the signal to be transmitted are signals that change between the voltage Va and the voltage Vb (Va> Vb).
In the conventional differential serial transmission method, the signal (S) to be transmitted and the common voltage (Vcom) are combined, and the voltage level is VH, which is higher than the common voltage (Vcom) by Vs, A positive-polarity transmission signal (PS) composed of a voltage VL that is lower by a voltage Vs than the common voltage (Vcom) is generated.
Similarly, the inverted signal (/ S) and the common voltage (Vcom) are synthesized, and the voltage level is higher than the common voltage (Vcom) by the voltage VH higher than the common voltage (Vcom) and the common voltage (Vcom). Also, a negative-polarity transmission signal (NS) composed of a voltage VL having a low potential by the voltage Vs is generated.
The positive transmission signal (PS) is input to the controller circuit 100 via the positive transmission line in the pair of transmission lines, and the negative transmission signal (NS) is transmitted through the pair of transmission lines. Then, the signal is input to the controller circuit 100 via the transmission line on the negative polarity side.
The controller 100 restores the signal (S) by taking the difference between the positive signal (PS) and the negative signal (NS).
As described above, the pair of transmission lines is composed of a positive transmission line and a negative transmission line, and this pair of transmission lines is referred to as a one-lane differential transmission line.

FIG. 10 is a diagram for explaining a conventional differential serial transmission system.
As shown in FIG. 10, in the conventional differential serial transmission method, a signal (Sa) and a constant common potential (Vcom) are synthesized in the transmission unit (TX1) to generate a positive polarity signal (FIG. a) PS) and a negative signal (NS in FIG. 9E) are generated and transmitted to the receiving unit (RX1) via the differential transmission path (LEN1) of the first lane, In the receiving unit (RX1), the signal (Sa) is restored by taking the difference between the positive signal (PS in FIG. 9A) and the negative signal (NS in FIG. 9E).
Similarly, in the transmission unit (TX2), the signal (Sb) and the common potential (Vcom) having a constant potential are combined, and a positive signal (PS in FIG. 9A) and a negative signal (FIG. 9) are combined. 9 (e) NS) and is transmitted to the reception unit (RX2) via the differential transmission line (LEN2) of the second lane, and the reception unit (RX2) has a positive signal (FIG. 9 (a)) and a negative signal (NS in FIG. 9 (e)) are taken to restore the signal (Sb).
Here, in the liquid crystal display device of the present embodiment, the transmission units (TX1, TX2) are arranged on the external main body side, and the reception units (RX1, RX2) are arranged in the controller circuit 100. In FIG. 10, the resistor R is a termination resistor.
As described above, in the conventional differential serial transmission system, the common voltage (Vcom) is a constant potential voltage that is not intentionally changed. Therefore, as shown in FIG. 10, when a two-lane differential transmission line is used, only two signals can be transmitted unless the time division method is used. Further, when the time division method is used, more than two signals can be transmitted, but the total transmission amount within a certain time is reduced according to the occupation ratio of each transmission signal.

[Differential serial transmission system of the embodiment of the present invention]
In this embodiment, a common signal (SC) that changes in synchronization with the signal is used instead of the common voltage (Vcom) having a constant potential.
FIG. 2 is a schematic diagram showing signal waveforms transmitted in the differential serial transmission method in the liquid crystal display device according to the embodiment of the present invention. 2A is a positive transmission signal (PS), FIG. 2B is a signal to be transmitted, FIG. 2C is a common signal (common signal of the present invention; SC), FIG. 2 (d) is an inverted signal (/ S) of the signal (S) to be transmitted, FIG. 2 (e) is a negative transmission signal (NS), and FIG. 2 (f) is a restored signal (S). FIG. 2G shows the restored common signal (SC).
As shown in FIG. 2 (c), in this embodiment, the common signal (SC) is not a constant potential signal, but a signal whose amplitude changes between the voltage Vc and the voltage Vd. The timing at which the voltage (Vc) changes to the voltage (Vd) and the timing at which the voltage (Vd) changes to the voltage (Vc) are synchronized with the signal (S) (or the inverted signal (/ S)). Signal.
In the present embodiment, a signal (S) to be transmitted and a common signal (SC) are combined, and when the signal (S) to be transmitted is a voltage Va having a higher potential than the center potential (So), If the voltage (V) is higher than the common potential (SC) and the signal (S) to be transmitted is lower than the central potential (So), the voltage Vs is higher than the common signal (SC). A positive transmission signal (PS) composed of a low potential voltage is generated.
Similarly, the inverted signal (/ S) of the signal (S) to be transmitted and the common signal (SC) are synthesized, and the inverted signal (/ S) has a voltage Va having a higher potential than the center potential (So). In this case, when the voltage Vs is higher than the common signal (SC) by a voltage Vs and the signal (S) to be transmitted is a voltage Vb lower than the center potential (So), the common signal (SC) Also generates a negative transmission signal (NS) consisting of a voltage having a low potential by the voltage of Vs.
In other words, in the present embodiment, the positive transmission signal (PS) and the negative transmission signal (NS) have a voltage level of a high potential VH, a low potential VL, and an intermediate potential. The signal takes a ternary voltage of Vo (= (VH + VL) / 2).

The positive transmission signal (PS) is input to the controller circuit 100 via the positive transmission line in the pair of transmission lines, and the negative transmission signal (NS) is transmitted through the pair of transmission lines. Then, the signal is input to the controller circuit 100 via the transmission line on the negative polarity side.
Then, in the controller circuit 100, by taking the difference between the positive transmission signal (PS) and the negative transmission signal (NS), as shown in FIG. Can be generated.
Further, in this embodiment, by dividing the potential difference between the positive transmission signal (PS) and the negative transmission signal (NS), as shown in FIG. ) Can be restored.
In this embodiment, a common signal (SC) that changes in synchronization with the signal is used instead of the common voltage (Vcom) having a constant potential.
Here, preferably, the common signal (SC) is synchronized with, for example, the signal (S) to be transmitted or the inverted signal (/ S), and changes with a phase difference as small as possible with respect to these signals. Good signal to do. This is because, if there is a phase difference, a substantially higher frequency component is generated. However, since this high frequency component is attenuated, there is a high possibility that the transmitted signal is changed.

FIG. 3 is a diagram for explaining a differential serial transmission method in the liquid crystal display device according to the embodiment of the present invention.
As shown in FIG. 3, in the differential serial transmission system of the present embodiment, the signal (Sa) and the common signal (SCa) are synthesized in the transmission unit (TX1) to generate a positive signal (FIG. ) PS) and a negative signal (NS in FIG. 2E) are generated and transmitted to the receiving unit (RX1) via the differential transmission path (LEN1) of the first lane. In the part (RX1), the signal (Sa) is restored by taking the difference between the positive signal (PS in FIG. 2 (a)) and the negative signal (NS in FIG. 2 (e)).
Similarly, in the transmission unit (TX2), the signal (Sb) and the common signal (SCb) are combined, and the positive signal (PS in FIG. 2A) and the negative signal (FIG. 2B). NS) of the second lane, and is transmitted to the reception unit (RX2) via the differential transmission path ((LEN2) of the second lane. In the reception unit (RX2), a positive signal (FIG. The signal (Sb) is restored by taking the difference between (PS) of a) and the negative polarity signal (NS of FIG. 2 (e)).
Further, in the present embodiment, in the transmission unit (TX3), the signal (Sc) and the common voltage (Vcom) having a constant potential are synthesized, and the positive signal (PS in FIG. 2A) and the negative polarity 2 (NS in FIG. 2 (e)) is generated, and the positive signal (PS in FIG. 2 (a)) is input to the transmission unit (TX1) as the common signal (SCa). The signal (NS in FIG. 2E) is input to the transmission unit (TX2) as a common signal (SCb).

Further, in the receiving unit (RX1), the potential difference between the positive polarity signal and the negative polarity signal is divided by the terminating resistor (R) to restore the common signal (SCa). Similarly, the receiving unit (RX2) ), The potential difference between the positive polarity signal and the negative polarity signal is divided by the terminating resistor (R) to restore the common signal (SCb).
Then, in the receiver (RX3), the signal (Sc) can be restored by taking the difference between the common signal (SCa) and the common signal (SCb).
As described above, in the present embodiment, the positive transmission line composed of both the positive and negative transmission lines of the differential transmission line (LEN1) of the first lane and the differential transmission of the second lane. A primary extension transmission line is formed by a negative transmission line composed of both positive and negative transmission lines of the line (LEN2), and one signal is transmitted using the primary extension transmission line. Can be made.
That is, in this embodiment, it is possible to transmit three signals through a 2-lane differential transmission line without changing the transmission clock.

FIG. 4A is a diagram for explaining an extended differential serial transmission method in the liquid crystal display device according to the embodiment of the present invention.
As shown in FIG. 4A, in the extended differential serial transmission system of the present embodiment, a signal (Sa) and a common signal (SCa) are synthesized in the transmission unit (TX1) to obtain a positive polarity signal. (PS in FIG. 2 (a)) and a negative polarity signal (NS in FIG. 2 (e)) are generated and transmitted to the receiving unit (RX1) via the first lane (LEN1). In the part (RX1), the signal (Sa) is restored by taking the difference between the positive signal (PS in FIG. 2 (a)) and the negative signal (NS in FIG. 2 (e)).
Further, in the transmission unit (TX2), the signal (Sb) and the common signal (SCb) are combined, and a positive signal (PS in FIG. 2A) and a negative signal (FIG. 2B). NS) and is transmitted to the receiving unit (RX2) via the second lane (LEN2). In the receiving unit (RX2), the positive signal (PS in FIG. 2A) and the negative electrode The signal (Sb) is restored by taking the difference of the sex signal (NS in FIG. 2E).
Further, in the transmission unit (TX4), the signal (Sc) and the common signal (SCc) are synthesized, and a positive signal (PS in FIG. 2A) and a negative signal (FIG. 2E). NS) and is transmitted to the receiving unit (RX4) via the third lane (LEN3). In the receiving unit (RX4), a positive signal (PS in FIG. 2A) and the negative electrode The signal (Sc) is restored by taking the difference of the sex signal (NS in FIG. 2 (e)).
Further, in the transmission unit (TX5), the signal (Sd) and the common signal (SCd) are synthesized, and a positive signal (PS in FIG. 2A) and a negative signal (FIG. 2B). NS) and is transmitted to the receiving unit (RX5) via the fourth lane (LEN4). In the receiving unit (RX5), the positive signal (PS in FIG. 2A) and the negative electrode The signal (Sd) is restored by taking the difference of the sex signal (NS in FIG. 2E).

Further, in the transmission unit (TX3), the signal (Se) and the common signal (SCe) are combined, and a positive signal (PS in FIG. 2A) and a negative signal (FIG. 2E). NS) and a positive signal is input to the transmission unit (TX1) as a common signal (SCa) and a negative signal is input to the transmission unit (TX2) as a common signal (SCb). To do.
Further, in the receiving unit (RX1), the potential difference between the positive polarity signal and the negative polarity signal is divided by the terminating resistor (R) to restore the common signal (SCa). Similarly, the receiving unit (RX2) ), The potential difference between the positive polarity signal and the negative polarity signal is divided by the terminating resistor (R) to restore the common signal (SCb).
Then, in the receiving unit (RX3), the signal (Se) can be restored by taking the difference between the common signal (SCa) and the common signal (SCb).
Thus, in this embodiment, the positive polarity side transmission path composed of both the positive polarity side and negative polarity side transmission lines of the first lane (LEN1), and the positive polarity side and negative polarity of the second lane (LEN2). Since the primary extension transmission line which consists of the negative polarity side transmission line which consists of both transmission lines on the right side is formed, one signal can be transmitted using the primary extension transmission line.

Further, in the transmission unit (TX6), the signal (Sf) and the common signal (SCf) are combined, and a positive signal (PS in FIG. 2A) and a negative signal (FIG. 2E). NS) and a positive signal is input to the transmission unit (TX4) as a common signal (SCc) and a negative signal is input to the transmission unit (TX5) as a common signal (SCd). To do.
Further, in the receiving unit (RX4), the potential difference between the positive polarity signal and the negative polarity signal is divided by the terminating resistor (R) to restore the common signal (SCc). Similarly, the receiving unit (RX5) ), The potential difference between the positive signal and the negative signal is divided by the terminating resistor (R) to restore the common signal (SCd).
Then, in the receiving unit (RX6), the signal (Sf) can be restored by taking the difference between the common signal (SCc) and the common signal (SCd).
As described above, in this embodiment, the positive polarity side transmission path including both the positive polarity side and negative polarity side transmission lines of the third lane (LEN3), and the positive polarity side and negative polarity of the fourth lane (LEN4). Since the primary extension transmission line which consists of the negative polarity side transmission line which consists of both transmission lines on the right side is formed, one signal can be transmitted using the primary extension transmission line.

In addition, in the transmission unit (TX7), the signal (Sg) and the common voltage (Vcom) having a constant potential are combined, and a positive signal (PS in FIG. 2A) and a negative signal (FIG. 2 (e) NS) and a positive signal as a common signal (SCe) is input to the transmitter (TX3), and a negative signal as a common signal (SCf) as a transmitter ( Input to TX6).
Further, in the receiving unit (RX3), the potential difference between the positive polarity signal and the negative polarity signal is divided by the terminating resistor (R) to restore the common signal (SCe). Similarly, the receiving unit (RX6) ), The potential difference between the positive signal and the negative signal is divided by the terminating resistor (R) to restore the common signal (SCf).
Then, in the receiving unit (RX7), the signal (Sg) can be restored by taking the difference between the common signal (SCe) and the common signal (SCd).
As described above, in this embodiment, the positive-side transmission path including the primary extended transmission lines of the first lane (LEN1) and the second lane (LEN2), the third lane (LEN3), and the fourth lane Since the secondary extended transmission line is configured with the negative polarity side transmission line composed of the primary extended transmission line in the lane (LEN4), one signal can be transmitted using the secondary extended transmission line.
That is, in the extended differential serial transmission system of the present embodiment, seven signals Sa to Sg can be transmitted by the four-lane differential transmission line LEN1 to LEN4.
FIG. 4B is a schematic diagram showing a signal waveform transmitted through the transmission line on the positive polarity side of the first lane (LEN1) in the extended differential serial transmission method shown in FIG. 4A. In FIG. 4B, PSa is a positive transmission signal of the signal (Sa), PCa is a common signal (SCa), and PCe is a common signal (SCe).
As shown in FIG. 4B, in the extended differential serial transmission system shown in FIG. 4A, a positive transmission signal (or a negative transmission signal) is a high potential VH as a voltage level. A signal having a four-value voltage of Vm1, a first intermediate potential Vm1, a second intermediate potential Vm2, and a low potential VL voltage (VH>Vm1>Vm2>VL); Become.

Even when a larger number of transmission lines are formed, an extended transmission line can be formed in the same manner. If N lane differential transmission lines composed of 2N transmission lines are formed, a maximum of (2N− The extra signal of 1) can be transmitted.
And the differential transmission line (including the primary and secondary extended differential transmission lines) of the total (2N-1) lanes is the transmission line on the positive polarity side and the transmission line on the negative polarity side of each lane. Since the wiring route of the same layer is used, the symmetry is good and it is suitable as a differential transmission line.
The differential serial transmission method using the above-described extended differential transmission line is a differential transmission line such as a one formed on a rigid board, a flexible board, or a differential transmission cable formed by overlapping a plurality of conductors. Any shape can be applied.
For this reason, there are few choices of materials and it is difficult to increase the transmission clock, the total number of wires is generally limited to two layers in order to ensure bendability, and the number of wires determined from the outer shape is severely limited. It is effective to apply to a flexible wiring board (FPC).
Therefore, by applying this embodiment to a flexible wiring board (FPC) used for an image display device such as a liquid crystal display device, a narrow flexible wiring board (FPC) is used, and the controller on the TFT substrate is used. More display data can be transmitted to and from the circuit 100.

As described above, in this embodiment, in the differential serial transmission system, an extended differential transmission line is configured using the common signals of the two lanes, and a signal is applied to the differential signal of two lanes. Three differential signals can be transmitted on the transmission line.
Furthermore, since the maximum (2N-1) number of differential signals can be simultaneously transmitted by the N-lane differential transmission line by expanding, the transmission data capacity can be increased without increasing the differential transmission line. it can.
By setting the number N of differential transmission lines constituting one lane as an even number, it is possible to configure a differential transmission line by combining wirings of the same extension order.
In general, a plurality of lanes of differential transmission lines on a flexible printed circuit board (FPC) are generally arranged in parallel. Accordingly, even in the extended differential transmission line, a differential transmission line having good symmetry between the transmission line on the positive polarity side and the transmission line on the negative polarity side can be configured.
For this reason, the transmission line which has high tolerance with respect to external noise can be obtained by taking the difference of the signal of the transmission line of a positive polarity side, and the transmission line of a negative polarity side. Furthermore, since the noise resistance is high, a transmission signal with a low amplitude voltage can be used, so that power consumption necessary for transmission can be minimized.

The differential serial transmission system of this embodiment is effective when N is an even number, but when N is an odd number, it is applied to an even number of (N−1) lanes excluding one lane. As a result, the transmission capacity can be increased.
In the case where the clock signal is an independent transmission method and uses a double data rate (DDR), it is desirable to apply the present embodiment to other differential transmission lines excluding the clock signal. . This is because, in the case of a double data rate (DDR), the transition timing of the clock signal and the transition of the data signal are shifted from each other, so that the combined signal of both requires transmission characteristics for higher frequencies.
In the flexible wiring board (FPC) using the differential serial transmission method of this embodiment, more signals can be transmitted using a small number of differential transmission lines formed in the same wiring layer. Therefore, even when the wiring layer and the wiring width are limited, more signals can be transmitted without increasing the transmission clock. Furthermore, since a necessary signal can be transmitted without increasing the wiring layer, it can be used without impairing the bendability of the flexible wiring board (FPC) as shown in FIG.

In the liquid crystal display device of this embodiment, more signals (display data or display control signals) can be transmitted to the controller circuit 100 without increasing the width of the flexible wiring board (FPC).
As shown in FIG. 6, in the flexible printed circuit board (FPC), the connecting portion to the housing side of the main body is often narrow in width, and the component placement position on the FPC for convenience of housing in the housing In many cases, the wiring formation width is limited, and the number of transmission lines cannot be increased unnecessarily.
In this embodiment, a necessary signal can be transmitted even in such a case, and a high-definition image can be displayed.
Alternatively, in this embodiment, since the data transmission speed can be improved without increasing the width of the flexible wiring board (FPC), a liquid crystal display device that displays a higher definition image can be configured. For this reason, since this liquid crystal display device can be installed in a narrow housing, it is possible to configure a high-quality image display terminal with high portability.
In the above description, the embodiment in which the present invention is applied to the liquid crystal display device has been described. However, the present invention is not limited to this, and the present invention is applied to other display devices such as an organic EL display. It goes without saying that it is possible.
As mentioned above, the invention made by the present inventor has been specifically described based on the above embodiments. However, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Of course.

DESCRIPTION OF SYMBOLS 10 Light guide plate 11 Lower frame 12 Crimp part 20 Base material layer 21 Ground layer 22 Wiring layer 23 Differential transmission line 24 Component 25 Shield layer 26 Insulating layer 100 Controller circuit
120 Power supply circuit 130 Drain driver 140 Gate driver 150 Memory circuit DL Video line (source line or drain line)
GL scan line (or gate line)
PX Pixel electrode CT Counter electrode TFT Thin film transistor LC Liquid crystal capacitor Cadd Retention capacitor PNL Liquid crystal display panel SUB1 First glass substrate SUB2 Second glass substrate DRV Drive circuit FPC Flexible wiring substrates LEN, LEN1, LEM2, LEN3, LEN4 Transmission lines TX1, TX2, TX3, TX4, TX5, TX6, TX7 Transmitter RX1, RX2, RX3, RX4, RX5, RX6, RX7 Receiver

Claims (13)

A transmission method for transmitting a signal by a differential serial transmission method via a pair of transmission lines,
The pair of transmission lines includes a positive transmission line that transmits a positive differential signal and a negative transmission line that transmits a negative differential signal.
The positive transmission line and the negative transmission line further transmit a common signal,
The positive and negative differential signals are signals having a voltage level that is higher in voltage by Vs than the common signal and lower in voltage by Vs than the common signal.
When the pair of transmission lines is referred to as a one-lane differential transmission line, the entire transmission line is composed of a plurality of lanes of differential transmission lines, and is transmitted by at least two lanes of the differential transmission lines. A transmission method characterized by temporally changing the amplitude of the common signal to be synchronized with the positive and negative differential signals. The entire transmission line includes a two-lane differential transmission line;
The first signal from the differential signal that transmits the differential transmission line of the first lane in the differential transmission line of the two lanes, and the second signal from the differential signal that transmits the differential transmission line of the second lane. And the primary extended differential transmission line composed of the differential transmission lines of the first and second lanes is regarded as the third differential transmission line, and the first and second differential transmission lines are considered. The transmission method according to claim 1, wherein the third signal is regenerated from a difference signal of the third differential transmission path, which is a difference of the common signal transmitted through the transmission line. The entire transmission line includes a 4-lane differential transmission line,
The first signal from the differential signal transmitted through the differential transmission line of the first lane among the differential transmission lines of the four lanes, and the second signal from the differential signal transmitted through the differential transmission line of the second lane. The signal is reproduced from the differential signal transmitted through the differential transmission line of the third lane, the third signal is reproduced from the differential signal transmitted through the differential transmission line of the fourth lane, and the first signal is reproduced. The primary extended differential transmission line composed of the differential transmission lines of the first and second lanes is regarded as the fifth differential transmission line, and the common signal transmitted through the first and second differential transmission lines is Considering the fifth signal from the differential signal and the primary extended differential transmission line composed of the differential transmission lines of the third and fourth lanes as the sixth differential transmission line, the third and fourth A sixth signal from the differential signal of the common signal transmitted through the differential transmission line, and the fifth signal And the secondary extended differential transmission line composed of the sixth primary extended differential transmission line is regarded as the seventh differential transmission line, and the common signal transmitted through the fifth and sixth differential transmission lines The transmission method according to claim 1, wherein the seventh signal is reproduced from the difference signal. The transmission line is formed on a wiring board composed of a combination of an insulating base material and two or more conductive layers,
2. The transmission method according to claim 1, wherein the positive transmission line and the negative transmission line of each lane are formed in the same conductive layer.   The transmission method according to claim 4, wherein the wiring board is a flexible wiring board.   6. The transmission method according to claim 5, wherein the conductive layer formed on the wiring board is two layers. A display panel having a plurality of pixels;
A display device comprising a drive circuit for driving the plurality of pixels,
A signal is supplied to the drive circuit from the outside via a pair of transmission lines in a differential serial transmission system,
The pair of transmission lines includes a positive transmission line that transmits a positive differential signal and a negative transmission line that transmits a negative differential signal.
The positive transmission line and the negative transmission line further transmit a common signal,
The positive and negative differential signals are signals having a voltage level that is higher in voltage by Vs than the common signal and lower in voltage by Vs than the common signal.
When the pair of transmission lines is referred to as a one-lane differential transmission line, the entire transmission line is composed of a plurality of lanes of differential transmission lines, and is transmitted by at least two lanes of the differential transmission lines. The display device is characterized in that the amplitude of the common signal to be changed changes with time in synchronization with the positive and negative differential signals. The entire transmission line includes a two-lane differential transmission line;
The first signal from the differential signal that transmits the differential transmission line of the first lane in the differential transmission line of the two lanes, and the second signal from the differential signal that transmits the differential transmission line of the second lane. And the primary extended differential transmission line composed of the differential transmission lines of the first and second lanes is regarded as the third differential transmission line, and the first and second differential transmission lines are considered. The display device according to claim 7, wherein the third signal is reproduced from the differential signal of the third differential transmission path, which is the difference of the common signal transmitted through the transmission line. The entire transmission line includes a 4-lane differential transmission line,
The first signal from the differential signal transmitted through the differential transmission line of the first lane among the differential transmission lines of the four lanes, and the second signal from the differential signal transmitted through the differential transmission line of the second lane. The signal is reproduced from the differential signal transmitted through the differential transmission line of the third lane, the third signal is reproduced from the differential signal transmitted through the differential transmission line of the fourth lane, and the first signal is reproduced. The primary extended differential transmission line composed of the differential transmission lines of the first and second lanes is regarded as the fifth differential transmission line, and the difference between the common signals transmitted through the first and second differential transmission lines The fifth differential transmission line is the fifth signal from the differential signal of the fifth differential transmission line, and the sixth differential transmission is performed through the primary extended differential transmission line composed of the differential transmission lines of the third and fourth lanes. 6th which is the difference between the common signals transmitted through the third and fourth differential transmission lines. The sixth signal is regarded as a differential signal of the differential transmission path, and the secondary extended differential transmission line composed of the fifth and sixth primary extended differential transmission lines is regarded as a seventh differential transmission line. The seventh signal is reproduced from a differential signal of a seventh differential transmission path, which is a difference between common signals transmitted through the fifth and sixth differential transmission lines. Display device. The transmission line is formed on a wiring board composed of a combination of an insulating base material and two or more conductive layers,
The display device according to claim 7, wherein the positive transmission line and the negative transmission line of each lane are formed in the same conductive layer.   The display device according to claim 10, wherein the wiring board is a flexible wiring board.   The display device according to claim 11, wherein the conductive layer formed on the wiring board is two layers.   The display device according to claim 7, wherein the display panel is a liquid crystal display panel or an organic electroluminescence panel.

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