Patent Publication Number: US-2004051815-A1

Title: Apparatus for providing tuner parameters in a television receiver

Description:
[0001] The invention generally relates to television receivers and, more particularly, to tuners used in television receivers. The term “television receiver” herein includes any television signal receiver with or without display.  
       [0002] Television tuners are used in television receivers such as television sets, video cassette recorders, home entertainment systems, and the like. The tuners are implanted as either discrete tuner modules or as onboard tuner circuits integrated into a chassis (“tuner-on-board”). Both discrete tuner modules and onboard tuner circuits often include phase lock loop (PLL) circuits that facilitate reception of television signals.  
       [0003]FIG. 1 depicts a portion of a prior art television chassis  100  that is conventionally found in a television receiver. The television chassis  100  comprises a tuner  104  having a phase lock loop  106  and a microprocessor  108  having an on-chip memory  110 . The tuner  104  is coupled to the microprocessor  108  via a communications bus  114 , e.g., an inter-integrated circuit ( 12 C) bus. The input port  102  for the television chassis  100  is coupled to an antenna, a cable feed or the like. The tuner  104  is typically a single conversion tuner, although a double conversion tuner may be used. The selection of a channel to receive by the television receiver is performed by the microprocessor  108  instructing the tuner  104  and the phases loop  106  to tune to a particular channel for reception. The tuner parameters  112  that are used to control the phase lock loop  106  are generally stored within an on-chip memory  110 . That is, a tuner&#39;s parameters are “hard coded” in the memory that is embedded in the microprocessor. As such, if the tuner  104  is a module that is manufactured separately from the television chassis, the tuner functionality must be well matched from tuner-to-tuner so that the same tuner parameters can be stored in the on-chip memory  110  in a hard coded manner for all tuner modules.  
       [0004] Electronic tuner control is a process whereby control data (also referred to herein as the tuner parameters) for a particular tuner are stored in nonvolatile memory (on-chip memory  110 ) within the microprocessor  108 . When a user selects a desired channel, the microprocessor  108  within the television receiver chassis  100  identifies (looks up) the control data stored in the nonvolatile memory  110  for the desired channel. The control data is then communicated to the television tuner  104 .  
       [0005] Tuner manufacturers use a variety of phase-locked loop (PLL) integrated circuits (ICs) in their tuner designs. The PLL IC is used to adjust the operating frequency of the tuner and thereby cause the television to receive the desired television channel. Since the frequency range to be covered spans over 700 MHZ, the PLL achieves broad band tuning by dividing this frequency range into convenient sections—typically three or four. These sections are known as bands, e.g., VHF low, VHF high and VHF.  
       [0006] The division of the covered frequency range is arbitrary and varies between tuner designs. This frequency range information for each band in the tuner forms part of the control data that is stored in nonvolatile memory  110 .  
       [0007] The stored control data also contains instructions that direct the PLL to synthesize the desired frequency and the mode of operation of that particular PLL IC. The control data controls the PLL for the selected channel, and controls various switch circuits within the tuner, i.e., VHF low, VHF high and UHF band selections.  
       [0008] While electronic control eases the design requirements, it narrows compatibility among television receiver components. The microprocessor  108  must contain specific routines for selecting and communicating the control data from the on-chip memory  110  to the tuner  104 . The tuner  104  must be adapted to accept the data and compensate for mismatches. As Such, replacement of malfunctioning television tuners in the field requires finding a new television tuner that is adapted to be controlled by a particular microprocessor and a particular set of tuner parameters.  
       [0009] When discrete tuner modules are utilized within the television chassis and those modules are manufactured by various tuner manufacturers, the tuner parameters that are to be stored in the on-chip memory varies from tuner-to-tuner. As such, the on-chip memory must be specially programmed with different data for each and every tuner type that is supplied from a different manufacturer for the television chassis. Since on-chip memory storage is of a limited size, it is not practical to store tuner parameters for every type of tuner that can be used with a television chassis. As such, a single set of parameters is stored for a particular tuner In the on-chip memory  110 . Thus, a faulty tuner can not be replaced without replacing the microprocessor  108 .  
       [0010] Therefore, the need exists in the art for a method and apparatus for flexibly storing tuner parameters within a television chassis  
       [0011] The present invention is a television chassis comprising a tuner, a microprocessor, a communications bus and a replaceable nonvolatile memory, e.g., an electrically erasable programmable read only memory (EEPROM). The replaceable nonvolatile memory is programmed to contain the tuner control parameters for a tuner at the time of chassis manufacture, allowing for quick adjustment to a change in the tuner type. The memory can be programmed for a tuner such that on the manufacturing floor the tuner from each manufacturer is supplied with matching control parameters for the television chassis that the tuner is going to be placed within. Once the television is assembled, the tuner parameters are recalled by the microprocessor and used to facilitate electronic control of the tuner and phase lock loop in a conventional manner. While using a separate programmable memory to store the tuner parameters, the invention avoids the problem of having to program an on-chip memory within the microprocessor for each and every type of tuner module that is used in the television chassis.  
       [0012] So that the manner in which the above recited features of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are Illustrated in the appended drawings. 
     
    
    
     [0013] It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.  
     [0014]FIG. 1 depicts a portion of a block diagram of a prior art television chassis; and  
     [0015]FIG. 2 depicts a portion of a block diagram of a television chassis in accordance with the present invention. 
    
    
     [0016] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures.  
     [0017] After considering the following description, those skilled in the art will clearly realize that the teachings of this invention can be readily utilized in a television receiver. This disclosure involves a television tuner in which a rewritable memory is used in conjunction with a microprocessor to facilitate tuning of the tuner. The rewritable memory stores the tuner control parameters for a phase lock loop within the tuner.  
     [0018]FIG. 2 depicts a block diagram of one embodiment of a television chassis  200  in accordance with the invention. The television chassis  200  comprises an input port  102  for receiving RF signals, e.g., television signals, a tuner  104  having a phase lock loop  106 , a microprocessor  108  having on-chip memory  110 , and a rewritable memory  202  for storing tuner parameters  112 . The tuner  104  is coupled through a communications bus  114  to a tuner control system  204  comprising the microprocessor  108  and memory  202 . The tuner receives television signals through the port  102  that is typically connected to a cable, a digital video disk, a video cassette recorder, or any other source of television signals.  
     [0019] The tuner module  104  selects an RF signal corresponding to desired television channels selected from a plurality of channel locations in a frequency band provided by the RF source. The RF signals associated with television channels may be analog and/or digital television signals. The analog television signal may comprise a conventional National Television Standard Committee (NTSC) modulated signal within the United States. The digital television signal may comprise a vestigial side band (VSB) modulated signal in compliance with the Advanced Television Systems Committee (ATSO) standard A/53, for example, a high definition television (HDTV) signal. The system described herein could also be configured to function with other formats, such as European, by appropriate changes in the television control system  204 .  
     [0020] The tuner module  104  select the desired television channel to be displayed on a display pursuant to a tuning command generated by the microprocessor  108 . The microprocessor  108  is coupled to the tuner module  104  via the communications bus  114 . In the embodiment, the communications bus  114  may be an inter-integrated circuit ( 12 C) bus, a three wire bus or any type of communications bus. In addition to a tuning command generated by the microprocessor  108 , the microprocessor recalls the tuner parameters  112  from the memory  202  for use with tuner module  104 . These tuner parameters  112  are passed through the communications bus  114  to the phase lock loop  106  within the tuner module  104 .  
     [0021] Memory  202  is rewritable type memory of a nonvolatile nature that may include, but is not limited to, read only memory (ROM) or programmable read only memory (PROM), the later of which may be subdivided into an electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) and one time PROM (OTPROM). The memory  202  is simultaneously programmed with a plurality of other memories using “bulk” programming techniques prior to installing the memory  202  in the chassis  200 . Electronically programmable memory may be programmed with the correct tuner control information during chassis manufacture. The control data  112  comprises digital information necessary to for the tuner PLL  106  to synthesize the correct frequency for receiving selected television signals.  
     [0022] In this manner, the tuner module  104  is electronically tuned to provide the correct frequency and best performance for the desired television channel. The tuner module  104  contains all necessary data for tuner control after that tuner parameters are passed from the microprocessor to the phase lock loop  106  to facilitate tuner control. As such, the tuner module  104  is a discrete component within the television chassis  200  which allows, for example, the replacement of the tuner module  104  in the field without changing the television control system  204 , specifically, the microprocessor  102 . When using the invention, the tuner module  104  can be changed with a matched memory  202  to facilitate changing the tuner parameters  112  to match the new tuner  104 .  
     [0023] Although various embodiments that incorporate the teachings of the present invention have been shown and described in detail herein, those skilled in the art can readily devise many other varied embodiments that still incorporate these teachings. For example, the disclosed invention can be used for FM broadcast radio receivers.