Abstract:
A circuit and a method for an effective way to customize the display driver software of any type of LCD-display and any type of LCD-driver chip used in an LCD display system is achieved. This is important in a multiple sourcing environment where LCD driver chips and LCD modules from different vendors are used in LCD display systems. This is accomplished through identification and registration of the information relevant for the said software customization by storing said information in an LCD module identification register. A microprocessor controlling the LCD display system is reading this identification register and providing the software customization elements specific to the LCD-driver chip and to the LCD-module during an initialization step of the system.

Description:
BACKGROUND OF THE INVENTION 
   (1) Field of the Invention 
   The invention relates to liquid crystal display (LCDs) systems, comprising a microprocessor unit (MPU) and an LCD module comprising an LCD display and an LCD driver chip, and more particularly, to a circuit and a method to identify and to register in said LCD system information the physical characteristics of said LCD module and said LCD driver chip to provide an easy way to configure and customize the system software for said LCD driver chip and said LCD module. 
   (2) Description of the Prior Art 
   Every LCD module type and LCD driver chip type needs it own specific display driver software to be adapted to the specific requirements and parameters as specific memory organization, control register setting, number of characters per line required, contrast tables, etc. of specific LCD drivers. The system software of LCD display systems has to be configured according to the specific types of LCD-driver chips and LCD modules used. This situation makes multiple sourcing for LCD modules and LCD driver chips difficult, the system software required has to be adopted for each type of driver chip and LCD module used individually. Said specific adoption is a critical step in the manufacturing process. 
   In prior art multiple sourcing of LCD modules and LCD driver chips is often avoided to circumvent the handling problems linked with the requirement of customizing the driver software for every type of LCD modules and LCD driver chips used in the system with the disadvantage of not using the components available on the market at the best pricing conditions. Otherwise in prior art these multiple source components are being used on the expense of a significant handling effort for the complex customizing of the software, especially it has to be absolutely assured that the right software version is adopted to the specific type of LCD-driver chips and LCD-modules used in the LCD system. 
   Several prior art inventions describe the deployment of LCD-modules and LCD-driver chips. U.S. Pat. No. 5,825,341 to Pawlowski shows a control interface for a liquid crystal display having more than 80 characters using a pair of controller/driver devices. The usage of one or two standard controller/drivers of the same kind is recommended. U.S. Pat. No. 6,222,518 B1 to Ikeda et al. describes a data processing system including a bus and a display data generating circuit coupled to the bus for generating display data and a display apparatus coupled to the bus. U.S. Pat. No. 6,262,594 B1 to Cheung et al. discloses an integrated circuit chip having pads that are grouped into a number of groups and also having functional modules that share use of two or more groups of the pads for transferring signals to or from external circuitry. 
   SUMMARY OF THE INVENTION 
   A principal object of the present invention is to provide a method and a circuit for an easy handling of the LCD system software customization process regarding the specific requirements of specific types of LCD modules and LCD driver chips used as part of an LCD system. 
   A further object of the present invention is to provide a circuit in the LCD-display system to register and contain the information required for the identification of the specific LCD-module types and LCD-driver chip types used in an LCD system. 
   A still further object of the present invention is to implement an effective method of the adoption of the required system software version to drive the specific LCD module types and the specific LCD chip types used in an LCD display system. 
   In accordance with the objects of this invention an identification system for an LCD system comprising an LCD module and a microprocessor unit to control said LCD system is achieved. Said LCD module includes an LCD driver chip and an LCD display. An LCD information register is located within said LCD system for holding information required to identify the physical characteristics of said LCD driver chip and said LCD display. Means for providing said information to said microprocessor unit to customize the system software of said LCD module to the specific requirements of the said LCD driver chip and said LCD display are introduced. 
   In accordance with the objects of this invention an identification system for an LCD system comprising an LCD module and a microprocessor unit to control said LCD system is achieved. Said LCD module includes an LCD driver chip and an LCD display. An LCD information register is located within said LCD system for holding information required to identify the physical characteristics of said LCD driver chip and said LCD display. Any serial or parallel interface using any communications protocol can be used to provide said information to said microprocessor unit to customize the system software of said LCD module to the specific requirements of the said LCD driver chip and said LCD display. 
   In accordance to further objects of the invention a method for the customization of a system software that drives an LCD module in an LCD system is achieved. Said system includes said LCD module, a microprocessor unit, an LCD identification register, and wherein said LCD module includes an LCD driver chip and an LCD display. Information about the physical characteristics of said LCD driver chip and said LCD module is provided to said LCD identification register. Said information is inputted from said register into said microprocessor unit. The specific parameters required for the specific types of LCD driver chip and said LCD display are selected and assigned according to said information read from the said identification register by said microprocessor unit. Said parameters are supplied by said microprocessor unit to said LCD driver chip and said LCD module for said customization of said system software. 
   In accordance to further objects of the invention a method for the customization of a system software that drives an LCD module in an LCD system is achieved. Said system includes said LCD module, a microprocessor unit, an LCD identification register, and wherein said LCD module includes an LCD driver chip and an LCD display. Information about the physical characteristics of said LCD driver chip and said LCD module is provided to said LCD identification register wherein said physical characteristics contain information such as the manufacturer of the LCD-driver chip, the type of the LCD-driver chip, the version of the LCD driver chip, the manufacturer of the LCD-module, the type of the LCD-module, the version of the LCD-module and other relevant information. Said information is inputted from said register into said microprocessor unit. The specific parameters required for the specific types of LCD driver chip and said LCD display are selected and assigned according to said information read from the said identification register by said microprocessor unit. Said parameters are supplied by said microprocessor unit to said LCD driver chip and said LCD module for said customization of said system software. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings forming a material part of this description, there is shown: 
       FIG. 1  illustrates an LCD display system comprising an LCD-module, an LCD-driver chip, a microprocessor unit (MPU) with memory and an interface to an LCD driver chip. 
       FIG. 2  illustrates an example of an LCD-driver module with an LCD-driver chip including an LCD-system identification register and the placement of the configuration pads for an advantageous routing of VSS and VDD tracks. 
       FIG. 3  illustrates an example for a serial communication protocol to read out the LCD-module identification. 
       FIG. 4  illustrates a method of the customization of the driver software of the LCD-module and the LCD-driver chip. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The preferred embodiments disclose a novel method and circuits for the adoption of the software to drive a liquid crystal display (LCD) system to the specific requirements of any types of LCD driver chips and any types of LCD modules, functionally suitable for the requirements of said LOD system. This is very important for LCD systems wherein the LCD driver chips and LCD modules are coming from multiple suppliers, therefore being of different types and versions of said components and having different software requirements caused by e.g. different memory organizations and/or different control register settings. Every LCD module type and LCD driver chip needs its specific software display driver. The software to control LCD systems has to be configured for the individual types and versions of the LCD driver chip and the LCD module used. Using LCD module identification and registration as part of the total LCD system makes the system software customization for different driver chips types and different LCD modules types used in an LCD system much easier and therefore enables the manufacturer of said LCD system to buy the best offer for said components available on the market from multiple sources. 
   LCD displays are used in many different types of electronic consumer products such as mobile phones, organizers, navigation systems, etc. A typical LCD system is shown in FIG.  1 . The LCD system is comprising an LCD module  1  and a microprocessor unit (MPU)  4 . The LCD module is comprising an LCD display  2  and an LCD driver chip  3 . The MPU  4  communicates with the LCD driver via a serial interface lines  5 . VSS lines  6  and VDD lines  7  are providing the power supply for the LCD driver chip and the LCD display. A capacitor C stabilizes the high LCD driving voltage VLCD  11  generated by the LCD driver chip. The LCD driver chip  3  is driving rows  9 ,  10  and the columns  12  of the LCD display  2 . The LCD module identification register  8  is located within the LCD driver chip  3 . As example of an existing embodiment the MPU is mounted on a printed circuit, the LCD driver chip is mounted on the glass (COG) of the LCD module. 
   One key element of the invention is to keep the information about the specific types and characteristics of the LCD modules and the driver chips used in an LCD system in an LCD module identification register within said LCD system. Every type of an LCD driver chip and every type of an LCD display needs a specific parameter setting for the LCD system software as e.g. characters per line, brightness, contrast table etc. These parameters differ from the type of LCD modules and type of LCD driver chips used. Said LCD module identification register can be realized preferably on the LCD driver chip. Said identification register is being used to store information about the type of LCD driver chip and the type of LCD display used as part of said LCD system. Said LCD module identification register can be read by the MPU controlling the LCD system via the existing communication interface without increasing the number of signal connections from MPU to the LCD module. 
   The LCD module identification register can contain information for example about the manufacturer of the LCD driver chip, the type of the LCD driver chip, the version of the LCD driver chip, the manufacturer of the LCD module, the type of the LCD module, the version of the LCD module, etc. 
   There are various ways to supply said LCD module identification information to the LCD identification register. One simple and low cost approach is to supply the information about the LCD module used via identification (ID) pads on the LCD driver chip and the information about the LCD driver chip to said chip by using either mask programmable registers or fuse programmable registers or re-programmable registers such as e.g. E 2 PROM or other programming tools to be hold in the memory of said driver chip. Any of the information about the types of both said driver chip and said LCD module can be programmed inside the LCD driver chip using said one-time programmable or re-programmable registers. The supply of said information can be performed for instance during final test of the LCD system as an initialization step of said system. If one time programmable or programmable registers are used, the information about the LCD module can also be programmed into the driver chip at final test. 
   The information about the physical characteristics of the LCD modules can be supplied to ID pads by connections to either VDD tracks or VSS pads routed below the chip. Said supply is normally performed during the production process of the LCD module. The identification pads (ID) pads can be placed at any location required on the LCD driver chip. LCD driver chips for chips on glass (COG) applications in general have a high number of supply pads. Some of these supply pads can be used for LCD module identification without increasing the number of pads required. Replacing some of the VSS and/or VDD supply pads by ID pads in between the other VSS and VDD supply pads will not increase the track resistance of the supplies significantly and allows an easy way to supply the configuration information to the LCD module information register. 
   Depending on the way said identification information is supplied and stored said LCD identification register is implemented in one or two different ways. In case the identification information for both LCD module and LCD driver chip is supplied by one-time programmable or re-programmable registers said LCD identification register resides in the memory of said LCD driver chip. In case parts of said identification information are supplied to the ID pads and parts of said information is supplied by said programmable registers the LCD identification register will be divided in 2 parts, one part is in the register and the other part is hard coded on the ID pads of the driver chip. 
     FIG. 2  shows an example for the layout of an LCD module  1  with an LCD driver chip  3  and the placement of the identification (ID) pads (ID 0  . . . IDn)  26  used for the module identification. The same numbers for the main components used in  FIG. 1  are used in  FIG. 2  as well. The signal tracks to the LCD display are omitted. VDD  6  and VSS  7  are the power supply voltages for the LCD module. A few of the VSS pads  21  and VDD pads  22  are shown. The VSS  24  and VDD tracks  25  used to set the ID information are routed below the LCD driver chip (VSS and VDD track routing). The VSS track  25  below the LCD driver chip is beginning at the VSS pads  21  located left of the ID pads  26  and ends at the right sight of the LCD driver chip. The VDD track  24  is beginning at the left side of the VDD pads  22  and ends at the left side of the LCD driver chip. Using a configuration like this the ID pads  26  can be either connected to VDD or VSS and are able to be used as a configurable LCD module ID. In reality there will be more ID pads  26  used than shown on the drawing. The number of ID pads depends on the volume of information to be held in the LCD module identification register. The number of supply pads is sufficient to spare some of them as identification pads. The driver chip is surrounded segment driver pads  27  used for driving the segments of the display. Changing the ID information can be done by low effort changing the glass layout, just by modifying the configurable LCD module tracks. 
   The LCD module identification register can be read via any serial or parallel interface using any communication protocol. An example for a serial communication protocol is shown in FIG.  3 . This example shows a serial communication protocol to read out the LCD module identification register. The instruction sent by the MPU to read the said identification register on the driver chip is “00110000”. The Identification code sent back is B[ 7 : 0 ]. The signal called OENA represents the driver chip internal control signal for bi-directional SDIO. 
   The MPU has its own memory where the system software and related parameters of required types of driver chips and the LCD displays to operate the LCD system are stored. In an initialization step, for instance during the power up sequence the MPU can read the LCD module identification register and can then assign and load the specific software and the parameters required to the LCD driver chip. 
   It is obvious that this invention applies also for the case where more than one driver chips are used in an LCD system. In case all driver chips are identical it is sufficient to keep said LCD module identification register on one of the LCD driver chips used. In case the LCD driver chips have different physical characteristics, e.g. different types of LCD driver chips are driving the LCD rows and columns, said LCD module identification register has to be implemented on each LCD driver chip. In this case the MPU will read from each LCD driver chip said identification register and will supply the specific parameters to each of said LCD driver chips individually. 
     FIG. 4  illustrates a method how the LCD module identification register is used for the customization of the system software of the LCD display system. In step  41 , performed during the production/test of the driver/module), the information about the physical characteristics as type, manufacturer and version of the LCD driver chip and the LCD module used in the LCD display system is provided to the LCD module identification register. In step  42  a microprocessor is reading said information supplied to the said identification register before. In step  43  said microprocessor selects and assigns the parameters required for the specific LCD driver chip and for the LCD display used in the LCD system according to the result of the readout of step  42 . For instance the selected parameters could cover items as the number of characters per line, brightness, contrast table, etc. In step  44  the microprocessor supplies said selected parameters to the LCD driver chip and to the LCD display. Step  45  closes this initialization method of the system software. 
   While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the invention.