CN1142539C

CN1142539C - Liquid crystal display controller

Info

Publication number: CN1142539C
Application number: CNB981228143A
Authority: CN
Inventors: 朱安琪
Original assignee: Motorola Inc
Current assignee: NXP USA Inc
Priority date: 1997-11-26
Filing date: 1998-11-26
Publication date: 2004-03-17
Anticipated expiration: 2018-11-26
Also published as: JPH11231847A; SG71735A1; CN1222720A

Abstract

A DMA (direct memory access) controller 33 reads out picture element intensity data 60 from a memory 16, and feeds the data to a frame rate controller 37. This data 42 is stored in display data buffers 41, 41A, 41B and 41C depending on the frame synchronous signal 32, and switch a picture element 45 in corresponding display frames 50, 50A, 50B and 50C, thereby providing intensity to be displayed by the picture element intensity data 60.

Description

LCD controller

Technical field

The present invention relates to LCD (LCD) controller, particularly relate to the lcd controller of the quantity of required reduction storer.

Background technology

LCD has the matrix of image cell or pixel.Each pixel can become opaque state or pellucidity by the pairing voltage level conversion that applies, and shows represented information by the voltage level of selecting that applies.

Have been found that pixel can show selectable " grey " tone between opaque and pellucidity by change the frequency that pixel is changed between opaque and pellucidity.

In the display of N level gray shade scale, N be the expression different tones quantity or by opaque to pellucidity grade.Usually, the information of the expression gray level of each pixel is stored in the storer, is arranged in as is known in the pixel impact damper of lcd controller.In the binary radix native system, for the display with N level gray scale, the pixel impact damper must store each pixel log2N position.For example, when 4 gray levels of needs, the pixel impact damper must store 2 binary digits of each pixel or position, and when 16 gray levels of needs, the pixel impact damper stores 4 of each pixels.Therefore, the quantity of gray level is big more, and the pixel impact damper just needs big more memory span.

Summary of the invention

Purpose of the present invention provides a kind of lcd controller, and the demand of its memory span does not increase with the quantity of wanting the gray-scale displayed level substantially pro rata.

According to the present invention, a kind of display controller is used for providing pixel data to display equipment, it is characterized in that this display controller comprises: frame speed controller, link to each other with storer, and be used for receiving pixel brightness data and frame synchronizing signal from storer; The direct memory access controller is connected between described storer and the described frame speed controller, is used for control and transmits the pixel brightness data from described storer to described frame speed controller; Screen translation circuit is connected between described storer and the described frame speed controller, and the pixel brightness data level that is used for offering described frame speed controller moves a predetermined number pixel; The pixel impact damper is coupled to frame speed controller, is used for the frequency according to frame synchronizing signal, receives the pixel brightness data, and the pixel brightness data are offered display equipment, and wherein the pixel impact damper is only stored an information to each display element; With the cursor logical circuit, be connected between described frame speed controller and the described pixel impact damper, be used for cursor information is appended to the pixel brightness data that offer described pixel impact damper.

Its feature also is to comprise interface circuit, is connected between described pixel impact damper and the described display equipment, is used for the pixel brightness data set from described pixel impact damper is dressed up the form that is suitable for the pixel on the crossover display terminal device.

Description of drawings

Fig. 1 is the block diagram of a lcd controller of expression;

Fig. 2 is the block diagram of a simplification of lcd controller in the presentation graphs 1.

Embodiment

With reference to accompanying drawing, by the example embodiment that present invention will be further described;

Among Fig. 1, the information that LCD (LCD) controller 10 receives from CPU (central processing unit) (CPU) 12 comprises the information that is used for the information that shows and how shows display message on display 25.The information that is used to show points out that on the display 25 of display module 23 those pixels are to be transformed into ON and those pixels are to be transformed into OFF, and when these information provide when showing, this information only is that " black and white " shows.When how the information of display message comprises pixel brightness information, and when pointing out the selecteed frequency when each pixel is transformed into ON and OFF, particular pixels can show " gray scale " level or the tone that has selection.

Lcd controller 10 is connected to CPU12 and storer 16 through address bus 18 and data bus 21.Memory controller 14 is connected between storer 16 and the CPU12, by CPU12 control reference-to storage 16.Lcd controller 10 is also connected to the display module 23 of the display 25 that has PEL matrix.

Lcd controller 10 comprises the control register 31 that connects address bus 18 and data bus 21, and provides one to output to direct memory visit (DMA) controller 33.The control information that control register 31 receives and storage provides from CPU12, the operation of lcd controller 10 is determined in this control information.

Dma controller 33 also is connected to address bus 18 and data bus 21, and provides one to output to screen translation circuit 35.Dma controller 33 controls are by the data transmission of storer 16 to lcd controller 10.Dma controller 33 also has an input to be connected to control register 31, receives the control information of determining the dma controller operation from control register 31.Dma controller 33 also has the input and the input that is used for the full signal of reception buffer that are used to receive the low speed data signal.Dma controller 33 will more multidata be to lcd controller 10 from storer 16 conversion when the reception of low speed signal, and dma controller 33 stops to give lcd controller 10 from the memory map data when the reception of buffer full signal.

Some pixels of information level ground displacement that screen translation circuit 35 will show on display 25, pixel number is to be programmed in the control register 31.Screen translation circuit 35 has the output that is connected with frame speed controller 37.

Frame speed controller 37 received frame synchronizing signals (32 among Fig. 2) and comprise information from the pixel brightness of storer 16, and be controlled at the conversion or the ON/OFF frequency of pixel on the display 25, so that according to this pixel of pixel brightness data presentation.

Frame speed controller 37 provides exports to cursor logical circuit 39, and cursor logical circuit 39 provides one to export to pixel impact damper 41.Cursor logical circuit 39 is added to information at the pixel brightness of display 16 to cursor, and is controlled at the conversion or the ON/OFF frequency of pixel on the display 25, so that according to this pixel of pixel brightness data presentation.

Frame speed controller 37 provides exports to cursor logical circuit 39, and cursor logical circuit 39 provides one to export to pixel impact damper 41.Cursor logical circuit 39 is added to cursor on the information that shows on the display 25 and with predetermined cursor bitmap, carries out by the overlapping or the logical operation of pixel.

Pixel impact damper 41 is first in first out (FIFO) structures, keeps display message on the display 25.The information that provides from the output of pixel impact damper 41 only is to the ON/OFF transitional information of each pixel on display 25.The quantity that is used for the storage unit of bank bit in pixel impact damper 41 can equal the quantity of the pixel on the display 25.Typically, the quantity of storage unit is to lack than the quantity of pixel on the display 25 in pixel impact damper 41, and under the control of dma controller 31, carry out the transmission of pixel brightness data for several times to frame speed controller 37 from storer 16, provide translation data to the whole pixels on the display 25.Total amount adjustment according to the data message flow that produces by the amount of capacity of data-switching frequency and pixel impact damper 41.

Pixel impact damper 41 provides low speed data signal and the output of buffer full signal to dma controller 33.When the translation data in the pixel impact damper 41 was lower than predetermined value, the pixel impact damper provided low data-signal output.For example, when the predetermined value of the pixel impact damper with 4 data word capacities was 2 data words, the data word in impact damper was 2 or than 2 under the little situation, the pixel impact damper will produce the low speed data signal.When the data word in the pixel impact damper is 4, the pixel impact damper will stop the data from storer 16 are sent to frame speed controller 37.

The output of pixel impact damper 41 offers the LCD interface 42 of assembling video data, so that make the data overall width and the polarities match of it and control signal, display module 23.LCD interface 42 becomes the form of changing pixel on the suitable display 25 to the output transform of pixel impact damper 41, and the information after the conversion is offered display module 23.

Utilize the block diagram of simplifying among Fig. 2 to describe the operation of the lcd controller 10 that 4 grades of gray shade scales are shown.In 4 intensity levels one can be arranged in 4 grades of gray shade scale display elements 45 on display (25 among Fig. 1).According to 4 full screens of frame synchronizing signal display element successively, each is called as

frame

50,50A, 50B and 50C.

The quantity that pixel 45 among 4

frames

50,50A, 50B and the 50C is converted into the frame of ON determines that display (25 among Fig. 1) goes up the brightness of these pixels.When a pixel 45 was converted into ON in whole 4

frames

50,50A, 50B and 50C, this pixel had maximum brightness.When having a pixel to be transformed into ON in per two frames at 4

frames

50,50A, 50B and 50C, this pixel has lower brightness.When having a pixel to convert ON in per three frames at 4

frames

50,50A, 50B and 50C, this pixel has lower brightness.When a pixel all was converted to OFF in 4

frames

50,50A, 50B and 50C, that pixel had minimum brightness.

Need two binary digits or position to select in 4 intensity levels each for 4 intensity levels of each pixel 45.Here, need 8 for the row 47 of 4 pixels, and it is stored in the storer 16 as altitude information.

These 8 when constituting 4 pairs two, every pair corresponding with in 4 pixels 45 in the top row 47 of display (25 among Fig. 1) each.

For each

pixel

45,1 42 of pixel impact damper 41 storage, therefore, to 4 pixels 45 in the top row 47 of display (25 among Fig. 1), 4 of pixel impact damper 41 storages.The transition status of the pixel 45 in the pixel impact damper 41 in every 42 representative and the top row 47 of display (25 among Fig. 1) is corresponding.When pixel impact damper 41 metas 42 are 1 (scale-of-two), go up corresponding pixel with display (25 among Fig. 1) and be switched to ON, and when this position was 0 (scale-of-two), corresponding pixel were converted into OFF.

Therefore, pixel impact damper according to the present invention has for each pixel and only stores 1 advantage.Thereby the total quantity that is stored in pixel impact damper meta equals the quantity of pixel on the display, and irrelevant with the quantity of gray-scale displayed level.

According to the low data and the buffer full signal that receive from pixel impact damper 41, dma controller 33 sends the display brightness data from storer 16 to frame speed controller 37.On the frame synchronization frequency that is provided by frame synchronizing signal 32, frame speed controller 37 sequentially loads pixel impact damper 41 42 4 times by the video data position.These are by the content of pixel impact damper 41 and are illustrated in subsequently as 41A, the 41B of dotted line and mark and the content of the pixel impact damper 41 among the 41C and point out.

Frame 50 provides according to the pixel 45 in the top row 47 of the content conversion of pixel impact damper 41.Corresponding

frame

50A, 50B and 50C represent according to as at dotted line and

mark

41A, 41B and represented pixel impact damper 41 content subsequently of 41C, the pixel 45 in the top row 47 of conversion.

In operation, when frame speed controller 37 is determined first 2 of display brightness data 60 when being 11 (scale-of-two) of indication maximum brightness level, each of

frame

50,50A, 50B and 50C is stored 1 (scale-of-two) in first position of pixel impact damper 41.Similarly, when display brightness data 60 connect following 2 is indication during than 10 (scale-of-two) of low luminance level, and this frame speed controller 37 is 1 (scale-of-two) to each of these 4

frames

50,50A, 50B and 50C every the single storage of the storage of second position of the pixel impact damper 41 of

frame

50A and 50C.

Further, when 2 the 3rd settings of display brightness data 60 are when indicating 01 (scale-of-two) of low luminance level more, the single storage of the storage of the 3rd position of the pixel impact damper 41 of this frame speed controller 37 in the frame 50 of 4

frames

50,50A, 50B and 50C 1 (scale-of-two).In addition, when display brightness data 60 last 2 when being set to indicate 00 (scale-of-two) of minimum brightness level are not provided with the 4th in any one pixel impact damper 41 of this frame speed controller 37 couples of 4

frames

50,50A, 50B and 50C.

So lcd controller described herein has and utilizes fixing and a limited memory span that " gray scale " on display level is provided.By only being stored the translation data position, each pixel on the display reaches this purpose.

As mentioned above, the invention provides a kind of lcd controller, its storer necessary condition is constant relatively, and irrelevant with the number of grey levels of actual displayed.

Claims

1. a display controller is used for providing pixel data to display equipment, it is characterized in that this display controller comprises:

Frame speed controller links to each other with storer, is used for receiving pixel brightness data and frame synchronizing signal from storer;

The direct memory access controller is connected between described storer and the described frame speed controller, is used for control and transmits the pixel brightness data from described storer to described frame speed controller;

Screen translation circuit is connected between described storer and the described frame speed controller, and the pixel brightness data level that is used for offering described frame speed controller moves a predetermined number pixel;

The pixel impact damper is coupled to frame speed controller, is used for the frequency according to frame synchronizing signal, receives the pixel brightness data, and the pixel brightness data are offered display equipment, and wherein the pixel impact damper is only stored an information to each display element; With

The cursor logical circuit is connected between described frame speed controller and the described pixel impact damper, is used for cursor information is appended to the pixel brightness data that offer described pixel impact damper.

2. display controller according to claim 1, its feature also is to comprise interface circuit, be connected between described pixel impact damper and the described display equipment, be used for the pixel brightness data set from described pixel impact damper is dressed up the form that is suitable for the pixel on the crossover display terminal device.