Abstract:
There is provided a television tuner including a first amplifier for amplifying received signals having frequencies of VHF-L and VHF-H bands, a first converter for converting a frequency of the received signals having been amplified by the first amplifier, a second amplifier for amplifying a received signal having a frequency of UHF band, a second converter for converting a frequency of the received signal having been amplified by the second amplifier, a signal transmitter for transmitting an operation switching signal by which the VHF-L band, the VHF-H band, or the UHF band is selected, a detector for detecting that none of the VHF-L and VHF-H bands is selected, based on data about the VHF-L and VHF-H bands, represented by the operation switching signal, and a driver for driving the second amplifier and pausing the first amplifier when the detector detects that none of the VHF-L and VHF-H bands is selected, and pausing the second amplifier and driving the first amplifier when the detector detects that one of the VHF-L and VHF-H bands is selected.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a television tuner switching a mode between UHF and VHF modes to thereby receive signals having frequencies of UHF and VHF bands, a tuner integrated circuit (IC) for controlling operation modes of such a television tuner, and a method of controlling a television tuner. 
     2. Description of the Related Art 
     In general, three frequency bands are now utilized as radio wave for television broadcasting: Very High Frequency-Low (VHF-L) band; Very High Frequency-High (VHF-H) band; and Ultra High Frequency (UHF) band. 
     A so-called television tuner has conventionally selected a channel by means of a logical channel (LC) tuning circuit. However, it is quite difficult to cover the above-mentioned three bands by a single LC tuning circuit. Hence, a conventional television tuner has been designed to include three LC tuning circuits each associated with the above-mentioned three bands, which LC tuning circuits are alternately switched. This is the same in a LC oscillation circuit of a frequency converter. 
     In the United States, a frequency band for FM radio broadcasting is positioned between VHF-L and VHF-H bands for television broadcasting. Hence, when radio waves for television broadcasting in VHF-L and VHF-H bands are to be received, radio waves for radio broadcasting in FM band may interfere with them to thereby degrade images and/or sound in quality. In order to avoid such interference, it would be necessary to trap radio waves for radio broadcasting in FM band. 
     In cable television service now spreading in the United States, a frequency band of signals for cable television is almost the same as a frequency band of signals for radio wave for television broadcasting, but is assigned FM band used for radio broadcasting. Hence, when a cable television is in operation, it is impossible to trap FM band. 
     Hence, in a television tuner available in the United States, a FM trap circuit for trapping signals of FM band is connected to an antenna through which radio waves for television broadcasting are received. The FM trap circuit is operated when radio waves for television broadcasting in VHF-L and VHF-H bands are to be received, and is paused when signals of a cable television are to be received through a cable. 
     A television tuner now available is not designed to switch only a LC tuning circuit in order to switch signals to be received between VHF-L and VHF-H bands, and UHF band. Circuits for amplifying high frequency and circuits for converting frequency separately prepared for VHF-L and VHF-H bands, and UHF band are connected to a front stage of a LC tuning circuit to thereby define a circuit for receiving signals having a frequency of VHF-L and VHF-H bands, and a circuit for receiving signals having a frequency of UHF band. The thus defined circuits are wholly, selectively switched. 
     The television tuner having such a structure as mentioned above makes it possible to simplify a circuit structure thereof, suppress degradation in characteristics, and optimize noise figure (NF) and operation current of transistors constituting the circuit, in accordance with a band. The above-mentioned control for switching circuits for receiving signals having frequencies of VHF-L and -H bands, and UHF band is generally carried out by means of operation switching signals standardized by a micro-computer, using an integrated injection logic (IIL) gate as standard specification. 
     An example of conventional television tuners is explained hereinbelow with reference to FIGS. 1,  2 A and  2 B, wherein FIG. 1 is a block diagram of a television tuner, FIG. 2A is a partial block diagram of a tuner integrated circuit, and FIG. 2B illustrates data for switching a band. 
     As illustrated in FIG. 1, the illustrated television tuner  1  is comprised of a high frequency amplifying section  100 , a tuner integrated circuit  200 , a logical channel (LC) section  300 , and a control circuit  400 . 
     The high frequency amplifying section  100  amplifies signals for radio wave or cable television broadcasting. The tuner IC  200  converts the amplified television signals into an intermediate frequency. The control circuit  400  is comprised of a microcomputer in which a suitable control program is installed as software, and controls operation of the high frequency amplifying section  100  and the tuner IC  200 . 
     The tuner IC  200  includes a frequency converter  2  to which a tuner controller  3  is connected. The high frequency amplifying section  100  includes a first amplifier  4  for amplifying a frequency of UHF band, and a second amplifier  5  for amplifying frequencies of VHF-L and -H bands. The first and second amplifiers  4  and  5  are connected upstream to the frequency converter  2 . A FM trap circuit  6  is connected upstream to the second amplifier  5 . 
     The FM trap circuit  6  to which the second amplifier  5  is connected, and the first amplifier  4  are both connected to a switch device  7 , to which an antenna (not illustrated) for receiving radio wave broadcasting or a communication cable (not illustrated) for cable broadcasting is connected through an input terminal  8 . 
     The frequency converter  2  includes a first frequency mixer  11  for UHF band and a second frequency mixer  12  for VHF-L and -H bands, which are connected to a first local oscillator (LO)  13  for UHF band and a second local oscillator (LO)  14  for VHF-L and -H bands, respectively. 
     The first and second local oscillators  13  and  14  are connected to a phase locked loop (PLL) section  15  through a buffer amplifier  19 . The phase locked loop section  15  is connected to the first and second local oscillators  13  and  14  for feedback through logical channels  16  and  17  for UHF band, and VHF-L and -H bands, respectively, in the logical channel section  300 . 
     As mentioned above, the first and second amplifiers  4  and  5 , the first and second mixers  11  and  12 , the first and second local oscillators  13  and  14 , and the first and second logical channels  16  and  17  are equipped separately for UHF band, and VHF-L and -H bands, and are connected in series to thereby define a first circuit  500  for receiving signals having a frequency of UHF band, and a second circuit  600  for receiving signals having a frequency of VHF-L and -H bands. 
     The first and second local oscillators  13  and  14  oscillate at certain frequencies. The first and second mixers  11  and  12  convert frequencies of television signals in UHF band and VHF-L and -H bands into intermediate frequencies by mixing them with frequencies of oscillation made by the first and second local oscillators  13  and  14 . The phase locked loop section  15  outputs a control voltage to the first and second logical channels  16  and  17  in accordance with the oscillation frequencies of the first and second local oscillators  13  and  14 , respectively, and cooperates with the first and second logical channels  16  and  17  to control oscillation frequencies of the first and second local oscillators  13  and  14  by feed-back. 
     As illustrated in FIG. 1, the phase locked loop section  15  is comprised of a frequency divider  41 , a phase detector  42 , a standard oscillator  43 , a charge pump  44 , and a buffer amplifier  45 . The frequency divider  41  divides a local oscillation signal transmitted from the buffer amplifier  19 . The standard oscillator  43  transmits an oscillation signal having a certain frequency. 
     The phase detector  42  generates a voltage proportional to a difference in phase between a frequency division signal transmitted by the frequency divider  41  and the oscillation signal transmitted from the standard oscillator  43 . 
     The charge pump  44  increases an output voltage of the phase detector  42  up to a certain voltage. The buffer amplifier  45  removes high frequency parts out of the thus increased voltage, and outputs the resultant voltage to the first and second logical channels  16  and  17  as a control voltage. 
     The frequency divider  41  can vary a division ratio in accordance with a signal transmitted from the control circuit  400  in order to conform to a received channel. Hence, an output signal transmitted from the frequency divider  41  has a certain frequency regardless of a frequency of a received signal. 
     The standard oscillator  43  can vary its oscillation frequency in accordance with the control signal transmitted from the control circuit  400  in order to conform to a band and/or channel interval of various areas. 
     An UV switching buffer  18  is connected to the first and second mixers  11  and  12 , and is connected further to a tuner control section  3 . The tuner control section  3  includes a band switching buffer  21  which is provided with output terminals P 1 , P 2 , P 3 , and P 4  arranged in a row in this order. Control signals for VHF-L band, VHF-H band, FM band, and UHF band are transmitted through the output terminals P 1 , P 2 , P 3 , and P 4 . 
     The output terminal for UHF band is connected to the first amplifier  4  used for UHF band. The output terminals P 1  and P 2  for VHF-L and VHF-H bands, respectively, are both connected to the second amplifier used for VHF-L and VHF-H bands. The output terminal P 4  for UHF band is connected not only to the first amplifier  4 , but also to the UV switching buffer  18 . 
     The band switching buffer  21  is connected to a data converter  22 , to which the phase locked loop section  15  and the control circuit  400  are connected. More specifically, as illustrated in FIG. 2A, the control circuit  400  is connected to the data converter  22  through an IIC bus  23  including a data input wiring  24  and a clock input wiring  25 . These input wirings  24  and  25  are connected to a serial-parallel converter  26  of the data converter  22 . 
     The serial-parallel converter  26  is comprised of eight D-type flip-flop circuits  27  to  35  which are electrically connected in serial to each other so that an input terminal of a flip-flop circuit located upstream is connected to a normal output terminal of a flip-flop circuit located downstream. Normal output terminals of the first four flip-flop circuits  27 ,  28 ,  29  and  30  of the serial-parallel converter  26  are connected in parallel to input terminals of the remaining four flip-flop circuits  32 ,  33 ,  34 , and  35  constituting a data latch circuit  31 . A 8-clock counter  36  connected to the clock input wiring  25  is connected to controls terminals of the four flip-flop circuits  32 ,  33 ,  34 , and  35  constituting the data latch circuit  31 . 
     Normal output terminals of the four flip-flop circuits  32 ,  33 ,  34 , and  35  are connected in parallel to a four-bit band switching buffer  37 . Four bit buffers equipped with the band switching buffer  37  are connected to the output terminals P 1 , P 2 , P 3  and P 4  through which the control signals for UHF band, FM band, VHF-H band, and VHF-L band are transmitted. 
     Though detailed later, 8-bit operation switching signals by each of which indicates as one-bit data that VHF-L band, VHF-H band, UHF band, or none of them is selected are input in serial to the serial-parallel converter  26  of the tuner controller  3  from the control circuit  400 . The band switching buffer  37  of the tuner controller  3  transmits at least four-bit operation switching signals in parallel by each of which indicates as one-bit data that VHF-L band, VHF-H band, UHF band, or none of them is selected. 
     As illustrated in FIG. 2A, the band switching buffer  37  includes first, second, third and fourth bit buffers B 1 , B 2 , B 3 , and B 4 . The first and second bit buffers B 1  and B 2  retaining setting data D 1  and D 2  about VHF-L band and VHF-H band, respectively, are connected to the second amplifier  5  used for VHF-L and VHF-H bands. The third bit buffer B 3  retaining setting data D 3  about FM band is connected to the FM trap circuit  6 . The fourth bit buffer B 4  retaining setting data D 4  about UHF band is connected to the first amplifier  4  used for UHF band, and further to the UV switching buffer  18  of the frequency converter  2  through a control output wiring  38 . 
     The first and second bit buffers B 1  and B 2  of the band switching buffer  37  are connected further to the second amplifier used for VHF-L and -H bands. The fourth bit buffer B 4  is connected to the first amplifier  4 , and further to the second amplifier  5  through an inverter. That is, one of the first and second amplifiers  4  and  5  operates in accordance with whether the setting data D 4  about UHF band is selected or not. The second amplifier  5  used for VHF-L and -H bands switches tuning frequency band of a built-in LC tuning circuit (not illustrated) between VHF-L band and VHF-H band in accordance with the setting data D 1  and D 2  about VHF-L band and VHF-H band, respectively. 
     The television tuner  1  having the above-mentioned structure is used for receiving television radio waves in the United States, for instance. In the United States, since FM band of radio waves used for radio broadcasting is assigned between VHF-H and VHF-L bands, it is necessary to trap FM band in order to avoid interference when radio waves in VHF-H and -L bands are to be received. 
     On the other hand, a frequency band for transmission signals of a cable television is almost the same as the above-mentioned frequency band of a television ground wave. However, since a channel of the frequency band for transmission signals of a cable television is assigned also to FM band, it is not possible to trap FM band when cable television signals are to be received. Hence, the television tuner  1  turns on the FM trap circuit  6  for trapping FM band or turns off the FM trap circuit  6  for pausing to trap FM band by the tuner controller  3  in accordance with whether radio waves in VHF-L and -H bands or cable signals of a cable television are received. 
     The above-mentioned radio waves for television broadcasting and wired signals for a cable television cover from VHF-L and -H bands to UHF band. For this reason, it is quite difficult to use a hardware for both UHF band, and VHF-L and -H bands. Specifically, the frequency converter  2  can receive signals having frequency ranging from UHF band to VHF-L and -H bands. However, since it is necessary to switch operation modes for receiving signals in UHF band and VHF-L and -H bands, the tuner controller  3  carries out such switching. 
     In more detail, as illustrated in FIG. 2B, 8-bit operation switching signals including data “X, X, X, X, U, FM, VH, VL” (indicates any data) each of which indicates VHF-L band, VHF-H band, FM band, UHF band, or none of them is selected, are input in serial in this order to the data input wiring  24  of the tuner controller  3  from the control circuit  400 . 
     Since the operation switching signals are serially input to the data input wiring  24  in synchronization with clock signals, at a time when an eighth clock signal has been input, the last four-bit data “U, FM, VH, VL” in the 8-bit operation switching signals is retained in the first to fourth flip-flop circuits  27  to  30  of the serial-parallel converter  26 , respectively. 
     When the eighth clock signal has been input to the data input wiring  24  as mentioned earlier, the 8-clock counter  36  which repeats counting clock signals transmits a latch signal to the data latch circuit  31 . Hence, the last four-bit data “U, FM, VH, VL” in the 8-bit operation switching signals, retained in the flip-flop circuits  27  to  30 , are transferred in parallel to the four flip-flop circuits  32  to  35  of the data latch circuit  31 , and retained therein. 
     The four-bit operation switching signals converted into parallel data are individually retained in the flip-flop circuits  32  to  35  of the data latch circuit  31 , and then, input in parallel to the four bit buffers B 1 , B 2 , B 3  and B 4  of the band switching buffer  37 . The parallel four-bit operation switching signals transmitted to the band switching buffer  37  indicates in each bit whether VHF-H band, VHF-L band, FM band, or UHF band is selected. 
     For instance, if UHF band is selected as a band for receiving signals, only the setting data for UHF band is set to be “1”, and other setting data for VHF-H, VHF-L and FM bands are set to be “0”. The band switching buffer  37  transmits control signals to the frequency converter  2  through the control output wiring  38  in accordance with the setting data for UHF band which is input to the fourth bit buffer B 4 . 
     The frequency converter  2  receives the control signals, as mentioned above. The UV switching buffer  18  switches the first and second mixers  11  and  12 , and the first and second local oscillators  13  and  14  in accordance with the control signals input thereto. As a result, an operation mode of the television tuner  1  is switched between VHF mode used for receiving signals having a frequency in VHF-L and -H bands, and UHF mode used for receiving signals having a frequency in UHF band. 
     As mentioned above, there are generated the operation switching signals for both VHF-L and -H bands for the purpose of switching a tuning frequency of the second amplifier to be used for VHF-L and -H bands. However, since switching between VHF and UHF modes is carried out in accordance with whether the setting data about UHF band indicates that UHF band is selected, VHF mode can be selected regardless of which one of the setting data about VHF-H and -L bands is selected. 
     The setting data about FM band is inevitably selected only when wired signals for a cable television are to be received, and is not selected when radio waves for television broadcasting are to be received. Hence, the FM trap circuit  6  to which the setting data about FM band is transmitted as a control signal from the band switching buffer  21  is designed not to trap FM band when the setting data about FM band indicates that FM band is selected, but trap FM band when the setting data indicates that FM band is not selected. 
     Thus, since FM band is trapped when radio waves for television broadcasting are received, radio waves in VHF-L and -H bands adjacent to FM band are well received by the second circuit  600 . In addition, since FM band is not trapped when wired signals for a cable television are received, wired signals in FM band can be well received by the second circuit  600 . 
     As the tuner IC  200  operating in such a manner as mentioned above, there may be employed TDA 6402A commercially available from Philips Ltd. (Philips data sheet, TDA 6402A, TDA 6403, TDA 6403A, Mar. 6, 1997). 
     In the above-mentioned television tuner  1 , since the tuner controller  3  switches operation modes of the frequency converter  2  in accordance with the operation switching signals transmitted from the control circuit  400 , the frequency converter  2  can receive UHF and VHF signals. 
     However, some television tuners are designed to have a different arrangement of the first and second amplifiers  4  and  5 , and the FM trap circuit  6  from the arrangement of those in the television tuner  1  illustrated in FIG.  1 . In such television tuners, data wirings connecting the band switching buffer  37  to the frequency converter  2  intersect with each other. 
     Data wirings for a television tuner are generally patterned on a printed wiring board. In order to intersect data wirings with each other as mentioned above, it would be necessary to form a wiring pattern in a multi-layered structure, or make jumper wirings, either of which would significantly lower a fabrication yield of a television tuner. 
     Hence, in order to avoid intersection of data wirings, a television tuner having such a layout as mentioned above changes an order of setting data about UHF and FM bands in the operation switching signals. As a result, the control signals are transmitted from the tuner controller  3  to the frequency converter  2  in accordance with the setting data about FM band in the operation switching signals. 
     For instance, when the frequency converter  2  and the tuner controller  3  are constituted of separate parts, what is necessary to do is merely to adjust a wiring structure. However, when the frequency converter  2  and the tuner controller  3  are constituted of the single tuner IC  200 , it is quite difficult to adjust a wiring structure in accordance with a format of the operation switching signals. 
     In order to solve such a problem, there has been suggested a tuner IC which can conform to the above-mentioned format of the operation switching signals. FIG. 3 illustrates such a tuner IC  700 . In the illustrated tuner IC  700 , the third bit buffer B 3  of the band switching buffer  37  is directly connected to the UV switching buffer  18  through the control output wiring  38 . As a tuner IC having such a structure as illustrated in FIG. 3, there is TDA 6402 commercially available from Philips Ltd. 
     That is, there has been used two kinds of formats of the operation switching signals to conform to two layouts of television tuners. As a result, there has been prepared two kinds of tuner ICs in accordance with the two kinds of the operation switching signals. Specifically, there has been prepared TDA 6402 and TDA 6402A both of which are commercially available from Philips Ltd., as the tuner ICs  200  and  700 , respectively. 
     As a result, fabrication yields for the tuner ICs  200  and  700  have remained low, and in addition, the number of fabrication steps and load on stock control has been increased. The above-mentioned two kinds of tuner ICs such as the tuner ICs  200  and  700  are generally designed to have the same appearance in order to keep compatibility in a mold for making a resin package and/or in a shape of a connector, which is accompanied with a problem that the tuner IC  200  or  700  may be incorporated into an inappropriate television tuner. 
     SUMMARY OF THE INVENTION 
     In view of the above-mentioned problems of the conventional television tuners, it is an object of the present invention to provide a television tuner which is capable of conforming to two kinds of formats of operation switching signals. It is also an object of the present invention to provide a tuner IC used for the above-mentioned television tuner, a method of controlling the above-mentioned television tuner, and a recording medium for causing a computer to act as the above-mentioned television tuner. 
     In one aspect of the present invention, there is provided a television tuner including (a) a first signal receiver for receiving signals having frequencies of VHF-L and VHF-H bands, (b) a second signal receiver for receiving signals having a frequency of UHF band, (c) a third signal receiver for receiving operation switching signals by each of which the VHF-L band, the VHF-H band, or the UHF band is selected, (d) a detector for detecting that none of the VHF-L and VHF-H bands is selected, based on data about the VHF-L and VHF-H bands, represented by the operation switching signals, and (e) a driver for driving the second signal receiver when the detector detects none of the VHF-L and VHF-H bands is selected. 
     In the above-mentioned television tuner, signals having frequencies of VHF-L and VHF-H bands are received by the first signal receiver, and signals having a frequency of UHF band are received by the second signal receiver. The operation switching signals by each of which the VHF-L band, the VHF-H band, or the UHF band is selected are received by the third signal receiver. If the detector detects none of VHF-L and VHF-H bands are selected, based on setting data about them, the second signal receiver is selectively operated by the operation switching signal indicating the detection result of the detector. Hence, even if the setting data about UHF band is altered in position in an operation switching signal, the second signal receiver is selectively operated or not operated, only based on the setting data about VHF-L and -H bands, regardless of alteration in position of the setting data about UHF band. 
     It should be noted that any parts constituting the above-mentioned television tuner might be formed so as to accomplish a function to be required. For instance, as mentioned later, there may be employed a specific hardware, a computer to which required functions are given by means of a program, functions accomplished in a computer by means of a suitable program, and a combination thereof. 
     The operation switching signal may be constituted as at least four-bit stream by each of which the VHF-L band, the VHF-H band, or the UHF band is selected, and may include two formats where the setting data about UHF and FM bands are exchanged in position. 
     For instance, the second signal receiver may include (b-1) a local oscillator which makes oscillation at a certain frequency, and (b-2) a frequency mixer for mixing an oscillation frequency of the local oscillator and a frequency of received signals, and converting the thus mixed frequencies into an intermediate frequency. 
     The local oscillator oscillates at a certain frequency, which is mixed with a frequency of a received signal, by the frequency mixer, to thereby convert into an intermediate frequency. Thus, a signal having a frequency in UHF band can be processed in the same manner as a signal having a frequency in VHF-L and -H bands. 
     There is further provided a television tuner including (a) a first amplifier for amplifying received signals having frequencies of VHF-L and VHF-H bands, (b) a first converter for converting a frequency of the received signals having been amplified by the first amplifier, (c) a second amplifier for amplifying a received signal having a frequency of UHF band, (d) a second converter for converting a frequency of the received signal having been amplified by the second amplifier, (e) a signal transmitter for transmitting an operation switching signal by which the VHF-L band, the VHF-H band, or the UHF band is selected, (f) a detector for detecting that none of the VHF-L and VHF-H bands is selected, based on data about the VHF-L and VHF-H bands, represented by the operation switching signal, and (g) a driver for driving the second amplifier and pausing the first amplifier when the detector detects that none of the VHF-L and VHF-H bands is selected, and pausing the second amplifier and driving the first amplifier when the detector detects that one of the VHF-L and VHF-H bands is selected. 
     In the above-mentioned television tuner, received signals having a frequency in VHF-L and -H bands are amplified by the first amplifier, and a frequency of the thus amplified signals is converted by the first converter. Similarly, received signals having a frequency in UHF band are amplified by the second amplifier, and a frequency of the thus amplified signals is converted by the second converter. The signal transmitter transmits the operation switching signals by each of which the VHF-L band, the VHF-H band, or the UHF band is selected. If the detector detects that none of VHF-L and VHF-H bands are selected, based on setting data about them, the driver drives the second amplifier and pauses the first amplifier. On the other hand, if the detector detects that one of the VHF-L and VHF-H bands is selected, the driver pauses the second amplifier and drives the first amplifier. Hence, even if the setting data about UHF band is altered in position in an operation switching signal, the first or second amplifier is selectively operated, only based on the setting data about VHF-L and -H bands, regardless of alteration in position of the setting data about UHF band. 
     For instance, the driver is comprised a first driver and a second driver, the first driver driving the second amplifier and pausing the first amplifier when the detector detects that none of the VHF-L and VHF-H bands is selected, the second driver pausing the second amplifier and driving the first amplifier when the detector detects that one of the VHF-L and VHF-H bands is selected. 
     In another aspect of the present invention, there is provided a tuner integrated circuit to be used for a television tuner including VHF mode for receiving a signal having a frequency of VHF-L and VHF-H bands, and UHF mode for receiving a signal having a frequency of UHF band, the tuner integrated circuit including (a) a signal receiver for serially receiving operation switching signals by each of which the VHF-L band, the VHF-H band, or the UHF band is selected, (b) a data converter for converting the operation switching signals serially received in the signal receiver into parallel signals, (c) a logical multiplier for logically multiplying binary data about the VHF-L and VHF-H bands, represented by the operation switching signals, and (d) a switching device for switching a mode of the television tuner between the UHF and VHF modes in accordance with a logical product provided by the logical multiplier. 
     The above-mentioned tuner integrated circuit may further include a data retainer for retaining the parallel signals therein. 
     Operation switching signals by each of which the VHF-L band, the VHF-H band, or the UHF band is selected are input in serial to the signal receiver. Then, the operation switching signals are converted by the data converter into parallel signals, and retained in the data retainer. The thus retained binary setting data about VHF-L and -H data in the operation switching signals are logically multiplied by the logical multiplier. A mode of a television tuner is switched by the switching device between UHF and VHF modes in accordance with the thus obtained logical product. Hence, even if the setting data about UHF and FM bands are altered in position in an operation switching signal, a mode in a television tuner is switched between UHF and VHF modes in accordance with the setting data about VHF-L and -H bands, regardless of alteration in position of the setting data about UHF and FM bands. 
     There is further provided a tuner integrated circuit to be used for a television tuner including VHF mode for receiving a signal having a frequency of VHF-L and VHF-H bands, and UHF mode for receiving a signal having a frequency of UHF band, the tuner integrated circuit including (a) a signal receiver for serially receiving operation switching signals by each of which the VHF-L band, the VHF-H band, or the UHF band is selected, (b) a data converter for converting the operation switching signals serially received in the signal receiver into parallel signals, (c) a wired AND for logically multiplying inverted outputs transmitted from the data converter, (d) a first integrated injection logic gate for inverting a logical product transmitted from the wired AND, (e) a second integrated injection logic gate for inverting data transmitted from the first integrated injection logic gate, and (f) a switching buffer for switching a mode of the television tuner between the UHF and VHF modes in accordance with an output transmitted from the second integrated injection logic gate. 
     The above-mentioned tuner integrated circuit may further include a data latch circuit for retaining the parallel signals therein. 
     It is preferable that each of the operation switching signals includes at least four-bit data each of which is indicative of whether the VHF-L band, the VHF-H band, or the UHF band is selected, in which case, the data latch circuit preferably includes at least four flip-flop circuits. 
     It is preferable that inverted outputs transmitted from first and second flip-flop circuits among the flip-flop circuits are logically multiplied by the wired AND. 
     Operation switching signals by each of which the VHF-L band, the VHF-H band, or the UHF band is selected are input in serial to the signal receiver. Then, the operation switching signals are converted by the data converter into parallel signals, and retained in the flip-flop circuits constituting the data retainer, for instance. Inverted outputs transmitted from first and second flip-flop circuits among the flip-flop circuits are logically multiplied by the wired AND, and the thus logically multiplied setting data is twice inverted by the first and second integrated injection logic gates, and then, input into the switching buffer. The switching buffer outputs control signals through a control output wiring in accordance with the setting data transmitted thereto. The control signals are input into a television tuner. Hence, even if the setting data about UHF and FM bands are altered in position in an operation switching signal, a mode in a television tuner is switched between UHF and VHF modes in accordance with the setting data about VHF-L and -H bands, regardless of alteration in position of the setting data about UHF and FM bands. 
     The term “inverted output” of the flip-flop circuits means an output terminal through which binary data which was input through an input terminal and inverted is output. The term “normal output” means an output terminal through which binary data which was input through an input terminal, but not inverted is output. 
     There is still further provided a tuner integrated circuit to be used for a television tuner including VHF mode for receiving a signal having a frequency of VHF-L and VHF-H bands, and UHF mode for receiving a signal having a frequency of UHF band, the tuner integrated circuit including (a) a signal receiver for serially receiving operation switching signals each including at least four-bit data each of which is indicative of whether the VHF-L band, the VHF-H band, or the UHF band is selected, (b) a data converter for converting the operation switching signals serially received in the signal receiver into parallel signals, (c) a data latch circuit including at least four flip-flop circuits for retaining the parallel signals therein, (d) a first integrated injection logic gate for inverting a normal output transmitted from a first flip-flop circuit among the flip-flop circuits, (e) a second integrated injection logic gate for inverting a normal output transmitted from a second flip-flop circuit among the flip-flop circuits, (f) a wired AND for logically multiplying outputs transmitted from the first and second integrated injection logic gates, (g) a third integrated injection logic gate for inverting a logical product transmitted from the wired AND, (h) a fourth integrated injection logic gate for inverting an output transmitted from the third integrated injection logic gate, and (i) a switching buffer for switching a mode of the television tuner between the UHF and VHF modes in accordance with an output transmitted from the fourth integrated injection logic gate. 
     Operation switching signals by each of which the VHF-L band, the VHF-H band, or the UHF band is selected are input in serial to the signal receiver. Then, the operation switching signals are converted by the data converter into parallel signals, and retained in the flip-flop circuits constituting the data retainer, for instance. The setting data of a normal output of the first flip-flop circuit in the data latch circuit is inverted by the first integrated injection logic gate, and the setting data of a normal output of the second flip-flop circuit in the data latch circuit is inverted by the second integrated injection logic gate. Those two inverted setting data are logically multiplied by the wired AND. The thus logically multiplied setting data is twice inverted by the third and fourth second integrated injection logic gates, and then, input into the switching buffer. The switching buffer outputs control signals through a control output wiring in accordance with the setting data transmitted thereto. The control signals are input into a television tuner. Hence, even if the setting data about UHF and FM bands are altered in position in an operation switching signal, a mode in a television tuner is switched between UHF and VHF modes in accordance with the setting data about VHF-L and -H bands, regardless of alteration in position of the setting data about UHF and FM bands. 
     There is yet further provided a tuner integrated circuit to be used for a television tuner including VHF mode for receiving a signal having a frequency of VHF-L and VHF-H bands, and UHF mode for receiving a signal having a frequency of UHF band, the tuner integrated circuit including (a) a signal receiver for serially receiving operation switching signals by each of which the VHF-L band, the VHF-H band, or the UHF band is selected, (b) a data converter for converting the operation switching signals serially received in the signal receiver into parallel signals, (c) a CMOS AND gate for logically multiplying inverted outputs transmitted from the data converter, and (d) a switching buffer for switching a mode of the television tuner between the UHF and VHF modes in accordance with an output transmitted from the CMOS AND gate. 
     The tuner integrated may further include a data latch circuit for retaining the parallel signals therein. Each of the operation switching signals preferably includes at least four-bit data each of which is indicative of whether the VHF-L band, the VHF-H band, or the UHF band is selected, in which case the data latch circuit preferably includes at least four flip-flop circuits. It is preferable that inverted outputs transmitted from first and second flip-flop circuits among the flip-flop circuits are logically multiplied by the CMOS AND gate. 
     Operation switching signals by each of which the VHF-L band, the VHF-H band, or the UHF band is selected are input in serial to the signal receiver. Then, the operation switching signals are converted by the data converter into parallel signals, and retained in the flip-flop circuits constituting the data retainer, for instance. Inverted outputs transmitted from first and second flip-flop circuits among the flip-flop circuits are logically multiplied by the CMOS AND gate, and the thus logically multiplied setting data is input into the switching buffer. The switching buffer outputs control signals through a control output wiring in accordance with the setting data transmitted thereto. The control signals are input into a television tuner. Hence, even if the setting data about UHF and FM bands are altered in position in an operation switching signal, a mode in a television tuner is switched between UHF and VHF modes in accordance with the setting data about VHF-L and -H bands, regardless of alteration in position of the setting data about UHF and FM bands. 
     There is still yet further provided a tuner integrated circuit to be used for a television tuner including VHF mode for receiving a signal having a frequency of VHF-L and VHF-H bands, and UHF mode for receiving a signal having a frequency of UHF band, the tuner integrated circuit including (a) a signal receiver for serially receiving operation switching signals each including at least four-bit data each of which is indicative of whether the VHF-L band, the VHF-H band, or the UHF band is selected, (b) a data converter for converting the operation switching signals serially received in the signal receiver into parallel signals, (c) a data latch circuit including at least four flip-flop circuits for retaining the parallel signals therein, (d) a first inverter for inverting a normal output transmitted from a first flip-flop circuit among the flip-flop circuits, (e) a second inverter for inverting a normal output transmitted from a second flip-flop circuit among the flip-flop circuits, (f) a CMOS AND gate for logically multiplying outputs transmitted from the first and second inverters, and (g) a switching buffer for switching a mode of the television tuner between the UHF and VHF modes in accordance with an output transmitted from the CMOS AND gate. 
     Operation switching signals by each of which the VHF-L band, the VHF-H band, or the UHF band is selected are input in serial to the signal receiver. Then, the operation switching signals are converted by the data converter into parallel signals, and retained in the flip-flop circuits constituting the data retainer, for instance. The setting data of a normal output of the first flip-flop circuit in the data latch circuit is inverted by the first inverter, and the setting data of a normal output of the second flip-flop circuit in the data latch circuit is inverted by the second inverter. Those two inverted setting data are logically multiplied by the CMOS AND gate. The thus logically multiplied setting data is input into the switching buffer. The switching buffer outputs control signals through a control output wiring in accordance with the setting data transmitted thereto. The control signals are input into a television tuner. Hence, even if the setting data about UHF and FM bands are altered in position in an operation switching signal, a mode in a television tuner is switched between UHF and VHF modes in accordance with the setting data about VHF-L and -H bands, regardless of alteration in position of the setting data about UHF and FM bands. 
     There is further provided a tuner integrated circuit to be used for a television tuner including VHF mode for receiving a signal having a frequency of VHF-L and VHF-H bands, and UHF mode for receiving a signal having a frequency of UHF band, the tuner integrated circuit including (a) a signal receiver for serially receiving operation switching signals by each of which the VHF-L band, the VHF-H band, or the UHF band is selected, (b) a data converter for converting the operation switching signals serially received in the signal receiver into parallel signals, (c) a CMOS NOR gate for making neither-nor operation of normal outputs transmitted from the data converter, and (d) a switching buffer for switching a mode of the television tuner between the UHF and VHF modes in accordance with an output transmitted from the CMOS NOR gate. 
     The tuner integrated circuit may further include a data latch circuit for retaining the parallel signals therein. It is preferable that each of the operation switching signals includes at least four-bit data each of which is indicative of whether the VHF-L band, the VHF-H band, or the UHF band is selected, in which case, the data latch circuit includes at least four flip-flop circuits. 
     The neither-nor operation by the CMOS NOR gate may be made for normal outputs transmitted from first and second flip-flop circuits among the flip-flop circuits. 
     Operation switching signals by each of which the VHF-L band, the VHF-H band, or the UHF band is selected are input in serial to the signal receiver. Then, the operation switching signals are converted by the data converter into parallel signals, and retained in the flip-flop circuits constituting the data retainer, for instance. Inverted outputs transmitted from first and second flip-flop circuits among the flip-flop circuits are negatively logically summed by the CMOS NOR gate, and the thus negatively logically summed setting data is input into the switching buffer. The switching buffer outputs control signals through a control output wiring in accordance with the setting data transmitted thereto. The control signals are input into a television tuner. Hence, even if the setting data about UHF and FM bands are altered in position in an operation switching signal, a mode in a television tuner is switched between UHF and VHF modes in accordance with the setting data about VHF-L and -H bands, regardless of alteration in position of the setting data about UHF and FM bands. 
     There is further provided a television tuner including (a) one of the above-mentioned tuner integrated circuits, (b) a first signal receiver for receiving signals having frequencies of VHF-L and VHF-H bands, (c) a second signal receiver for receiving signals having a frequency of UHF band, and (d) a driver for selectively driving one of the first and second signal receivers in accordance with an output transmitted from the tuner integrated circuit. 
     In the above-mentioned television tuner, signals having frequencies of VHF-L and VHF-H bands are received by the first signal receiver, and signals having a frequency of UHF band are received by the second signal receiver. The tuner integrated circuit outputs a control signal in accordance with setting data about VHF-L and -H bands in the operation switching signal, in accordance with which one of the first and second signal receivers is selectively operated by the driver. 
     In still another aspect of the present invention, there is provided a method of controlling a television tuner including a first signal receiver receiving signals having frequencies of VHF-L and VHF-H bands, and a second signal receiver receiving a signal having a frequency of UHF band, including the steps of (a) receiving an operation switching signal by which the VHF-L band, the VHF-H band, or the UHF band is selected, and (b) driving the second signal receiver and pausing the first signal receiver when none of the VHF-L and VHF-H bands is selected by the operation switching signal. 
     In accordance with the above-mentioned method, even if the setting data about UHF band is altered in position in an operation switching signal, the second signal receiver is selectively operated or not operated, only based on the setting data about VHF-L and -H bands, regardless of alteration in position of the setting data about UHF band. 
     There is further provided a method of controlling a television tuner including a first signal receiver receiving signals having frequencies of VHF-L and VHF-H bands, and a second signal receiver receiving a signal having a frequency of UHF band, including the steps of (a) receiving an operation switching signal by which the VHF-L band, the VHF-H band, or the UHF band is selected, (b) driving the second signal receiver and pausing the first signal receiver when none of the VHF-L and VHF-H bands is selected by the operation switching signal, and (c) driving the first signal receiver and pausing the second signal receiver when one of the VHF-L and VHF-H bands is selected by the operation switching signal. 
     In accordance with the above-mentioned method, the second signal receiver is selectively operated or not operated, only based on the setting data about VHF-L and -H bands, regardless of alteration in position of the setting data about UHF band, even if the setting data about UHF band is altered in position in an operation switching signal. 
     There is still further provided a method of controlling a television tuner including VHF mode for receiving a signal having a frequency of VHF-L and VHF-H bands, and UHF mode for receiving a signal having a frequency of UHF band, the method including the steps of (a) receiving an operation switching signal by which the VHF-L band, the VHF-H band, or the UHF band is selected, (b) making a logical product of binary data about the VHF-L and VHF-H bands, represented by the operation switching signal, and (c) switching a mode of the television tuner between the UHF and VHF modes in accordance with the logical product. 
     In accordance with the above-mentioned method, a mode of a television tuner is switched between UHF and VHF modes in accordance with a logical product of setting data about VHF-L and -H bands in the operation switching signal. Hence, even if the setting data about UHF and FM bands are exchanged in position in an operation switching signal, it is possible to switch a mode of a television tuner between UHF and VHF modes, regardless of alteration in position of the setting data about UHF and FM bands. 
     In yet another aspect of the present invention, there is provided a recording medium readable by a computer, storing a program therein for causing a computer to act as one of the above-mentioned television tuners. 
     The above and other objects and advantageous features of the present invention will be made apparent from the following description made with reference to the accompanying drawings, in which like reference characters designate the same or similar parts throughout the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram of a conventional television tuner. 
     FIG. 2A is a block diagram of a tuner integrated circuit constituting a part of the television tuner illustrated in FIG.  1 . 
     FIG. 2B illustrates data for switching a band, used in the tuner integrated circuit illustrated in FIG.  2 A. 
     FIG. 3 is a block diagram of a tuner integrated circuit constituting a part of another television tuner. 
     FIG. 4A is a block diagram of a tuner integrated circuit constituting a part of a television tuner in accordance with the first embodiment of the present invention. 
     FIG. 4B illustrates data for switching a band, used in the tuner integrated circuit illustrated in FIG.  4 A. 
     FIG. 5 is a block diagram of a tuner integrated circuit constituting a part of a television tuner in accordance with the second embodiment of the present invention. 
     FIG. 6 is a block diagram of a tuner integrated circuit constituting a part of a television tuner in accordance with the third embodiment of the present invention. 
     FIG. 7 is a partial block diagram of a tuner integrated circuit constituting a part of a television tuner in accordance with the fourth embodiment of the present invention. 
     FIG. 8 is a partial block diagram of a tuner integrated circuit constituting a part of a television tuner in accordance with the fifth embodiment of the present invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A television tuner in accordance with the first embodiment is explained hereinbelow with reference to FIGS. 4A and 4B. Parts or elements that correspond to those of the conventional television tuner illustrated in FIG. 1 have been provided with the same names, and are not detailed. FIG. 4A is a block diagram of a tuner integrated circuit constituting a part of the television tuner in accordance with the first embodiment of the present invention. 
     An illustrated tuner integrated circuit  101  includes a tuner controller  102  to which a frequency converter  103  is connected. The frequency converter  103  includes mixers (not illustrated) for mixing frequencies of UHF, VHF-L, and VHF-H bands, local oscillators (not illustrated), and a UV switching buffer  104  for switching the mixers and the local oscillators. 
     The tuner integrated circuit  101  includes a data input wiring  111  through which input signals are transmitted into the tuner integrated circuit  101 , and a clock input wiring  112  through which clock signals are input into the tuner integrated circuit  101 . These input wirings  111  and  112  are connected to a control circuit (not illustrated) acting as a signal transmitter from which operation switching signals are transmitted. 
     The data input wiring  111  and the clock input wiring  112  are connected to a serial-parallel converter  117  as a data converter, comprised of eight D-type flip-flop circuits  113  to  122  connected to each other in serial. The first four flip-flop circuits  113  to  116  of the serial-parallel converter  117  are connected in parallel to the remaining four D-type flip-flop circuits  119  to  122  constituting a data latch circuit  118  as a data retainer. 
     Each of the four flip-flop circuits  119  to  122  constituting the data latch circuit  118  has a control terminal connected to a 8-clock counter  123  connected to the clock input wiring  112 . The last four flip-flop circuits  119  to  122  constituting the data latch circuit  122  have normal output terminals connected to the output terminals P 1 , P 2 , P 3 , and P 4 , respectively, through a four-bit band switching buffer  124 . 
     That is, the first flip-flop circuit  119  of the data latch circuit  118  is connected to a first bit buffer B 1  retaining setting data D 1  about VHF-L band in an operation switching signal. The second flip-flop circuit  120  is connected to a second bit buffer B 2  retaining setting data D 2  about VHF-H band. The third flip-flop circuit  121  is connected to a third bit buffer B 3  retaining setting data D 3  about one of UHF and FM bands. The fourth flip-flop circuit  122  is connected to a fourth bit buffer B 4  retaining setting data D 4  about the other of UHF and FM bands. 
     The first and second flip-flop circuits  119  and  120  of the data latch circuit  118  have inverted output terminals connected to a wired AND  125  acting as a logical multiplier. First and second integrated injection logic (IIL) gates  126  and  127  are connected in series to the wired AND  125 . The second integrated injection logic gate  127  is connected further to the UV switching buffer  104  constituting a part of the frequency converter  103 . 
     The television tuner in accordance with the first embodiment, which included the above-mentioned tuner integrated circuit  101 , has a first circuit for receiving signals having frequencies in UHF band, and a second circuit for receiving signals having frequencies in VHF-L and -H bands, similarly to the conventional television tuner illustrated in FIG.  1 . The first circuit is comprised of an amplifier for amplifying signals having frequencies in UHF band, a mixer for mixing signals having frequencies in UHF band, a local oscillator for UHF band, a logical channel for UHF band, and the like, and receives radio waves and wired signals having frequencies in UHF band. The second circuit is comprised of an amplifier for amplifying signals having frequencies in VHF-L And -H bands, a mixer for mixing signals having frequencies in VHF-L and -H bands, a local oscillator for VHF-L and -H bands, a logical channel for VHF-L and -H bands, and the like, and receives radio waves and wired signals having frequencies in VHF-L, VHF-H, and FM bands. 
     Though detailed later, the setting data D 1  and D 2  about VHF-L and -H bands, respectively, in operation switching signals transmitted from the control circuit (not illustrated) to the tuner integrated circuit  101  are logically multiplied by the wired AND  125 . In accordance with the thus calculated logical product, the UV switching buffer  104  switches the mixer between a first mixer used for UHF band and a second mixer used for VHF-L and -H bands, and the local oscillator between a first local oscillator used for UHF band and a second local oscillator used for VHF-L and -H bands. As a result, a mode is switched between UHF mode and VHF mode in the frequency converter  103 . Hence, the UV switching buffer  104  acts as the switching device, the detector, the signal transmitter, and the driver. 
     In the first embodiment, the driver is comprised of a single UV switching buffer  104 . However, it should be noted that the driver may be comprised of two UV switching buffers one of which drives an amplifier for amplifying signals having frequencies in UHF band, and the like, and the other drives an amplifier for amplifying signals having frequencies in VHF-L and -H bands, and the like. 
     The television tuner  101  having the above-mentioned structure can receive signals having frequencies in UHF, VHF-L, and VHF-H bands, transmitted in the form of radio waves or wired signals, in the above-mentioned first and second circuits. A control for switching an operation mode between UHF mode and VHF mode is accomplished by the tuner controller  102 . 
     In the above-mentioned control for switching an operation mode, 8-bit operation switching signals each indicating that VHF-L, VHF-H, FM, or UHF band is selected or not in a single bit are input in serial to the data input wiring  111  of the tuner controller  102  from the control circuit (not illustrated in FIG.  4 A), and the thus input operation switching signals are converted into parallel signals by the serial-parallel converter  117 . 
     The thus converted operation switching signals are retained in the four flip-flop circuits  119  to  122  of the data latch circuit  118 , and then, input to the band switching buffer  124  in parallel. As a result, the band switching buffer  124  transmits control signals associated with the operation switching signals, to the high frequency amplifying section and the frequency converter  103 . 
     That is, the control signals associated with the setting data D 3  about UHF band are transmitted to the first and second amplifiers for amplifying signals for UHF and VHF bands, through the output terminal P 3  from the third bit buffer B 3  of the band switching buffer  124 . The first and second amplifiers are switched therebetween in accordance with the control signals. 
     Similarly, the control signals associated with the setting data D 1  and D 2  about VHF-L and -H bands are transmitted to the amplifier for amplifying signals for VHF band, through the output terminals P 1  and P 2  from the first and bit buffers B 1  and B 2  of the band switching buffer  124 . A tuning frequency band in a logical channel tuning circuit of the above-mentioned amplifier is switched between VHF-L and VHF-H bands in accordance with the setting data D 1  and D 2  about VHF-L and VHF-H bands, respectively. 
     In addition, the control signals associated with the setting data D 4  about FM band are transmitted to the FM trap circuit of the high frequency amplifying section through the output terminal P 4  from the fourth bit buffer B 4  of the band switching buffer  124 . Hence, the FM trap circuit does not trap FM band, if the setting data D 4  about FM band indicates that FM band is selected, but traps FM band, if the setting data D 4  about FM band indicates that FM band is selected. 
     The setting data D 1  and D 2  about VHF-H and VHF-L bands in the operation switching signals are retained in the first and second flip-flop circuits  119  and  120  of the data latch circuit  118 . As illustrated in FIG.  4  and Table 1 shown below, setting data A and B of inverted outputs transmitted from the first and second flip-flop circuits  119  and  120  are logically multiplied in the wired AND  125 . The thus logically multiplied setting data is inverted into setting data C by the first integrated injection logic gate  126 . The setting data C is inverted again into setting data D by the second integrated injection logic gate  127 , and input into the UV switching buffer  104 . 
     
       
         
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 VL 
                 VH 
                 U/FM 
                 FM/U 
                   
                   
                   
                   
                 UV 
               
               
                 B1 
                 B2 
                 B3 
                 B4 
                 A 
                 B 
                 C 
                 D 
                 SW 
               
               
                   
               
             
             
               
                 1 
                 0 
                 X 
                 X 
                 0 
                 1 
                 1 
                 0 
                 VHF 
               
               
                 0 
                 1 
                 X 
                 X 
                 1 
                 0 
                 1 
                 0 
                 VHF 
               
               
                 0 
                 0 
                 X 
                 X 
                 1 
                 1 
                 0 
                 1 
                 UHF 
               
               
                 1 
                 1 
                 X 
                 X 
                 0 
                 0 
                 1 
                 0 
                 VHF 
               
               
                   
               
             
          
         
       
     
     As mentioned earlier, the setting data D input into the UV switching buffer  104  becomes “1” only when the initial operation switching signals for VHF-H and VHF-L bands are both “0”. This means that the setting data D corresponds to switching between UHF and VHF modes of the frequency converter  103 . 
     In the first embodiment, the tuner integrated circuit  101  switches a mode in the frequency converter  103  in accordance with the setting data of VHF-L and VHF-H bands in the operation switching signals. Hence, even if the setting data about UHF and FM bands are exchanged in position in the operation switching signals, a mode in the frequency converter  103  is switched between UHF and VHF modes in accordance with the setting data about VHF-L and -H bands, regardless of alteration in position of the setting data about UHF and FM bands. 
     That is, the tuner integrated circuit  101  in the first embodiment can conform to the operation switching signals having two kinds of formats, which ensures a higher fabrication yield. In particular, a logical multiplier for producing control signals for the frequency converter  103 , based on the operation switching signals, is comprised of the wired AND  125 , and buffers for the wired AND  125  are comprised of two integrated injection logic gates  126  and  127 . As a result, it is possible to omit circuits which would be added to a conventional structure, resulting in higher productivity, smaller size, and lighter weight. 
     In addition, since portions outside the tuner integrated circuit  101  in the television tuner are not necessary to be altered or remodeled, it is possible to keep a fabrication yield of the television tuner high. 
     Furthermore, the tuner integrated circuit  101  in the first embodiment can be used for two kinds of television tuners having different formats in the operation switching signal. In such a case, it is not necessary to switch a dip switch in the tuner integrated circuit  101 , and hence, it would be avoidable, when television tuners are fabricated, that defective television tuners are fabricated by incorporating a tuner integrated circuit having a different format in the operation switching signal. 
     A television tuner in accordance with the second embodiment is explained hereinbelow with reference to FIG.  5 . Parts or elements that correspond to those of the first embodiment illustrated in FIG. 4A have been provided with the same reference numerals and names, and are not detailed. FIG. 5 is a block diagram of a tuner integrated circuit constituting a part of the television tuner in accordance with the second embodiment of the present invention. 
     In a tuner integrated circuit  201  of the television tuner in accordance with the second embodiment, a tuner controller  202  is connected to a frequency converter  103 , similarly to the tuner integrated circuit  101  illustrated in FIG.  4 A. 
     The tuner controller  202  has almost the same structure as that of the tuner controller  102  of the tuner integrated circuit  101 , but is different from the tuner controller  102  in a connection between the data latch circuit  108  and the UV switching circuit  104 . 
     In the second embodiment, the first flip-flop circuit  119  of the data latch circuit  118  has a normal output terminal connected to a first integrated injection logic gate  203 , and the second flip-flop circuit  120  of the data latch circuit  118  has a normal output terminal connected to a second integrated injection logic gate  204 . The first and second integrated injection logic gates  203  and  204  are both connected to a wired AND  205  acting as a logical multiplier. The wired AND  205  is connected in series to third and fourth integrated injection logic gates  206  and  207 , and the fourth integrated injection logic gate  207  is connected to the UV switching buffer  104  of the frequency converter  103 . 
     The tuner integrated circuit  201  in the second embodiment switches an operation mode of the frequency converter  103  in accordance with the operation switching signals, similarly to the tuner integrated circuit  101  illustrated in FIG.  4 A. 
     In the above-mentioned switching control, since the operation switching signals having been input in serial into the data input wiring  111  are converted into parallel signals by the serial-parallel converter  117 , and then, retained in the four flip-flop circuits  119  to  122  of the data latch circuit  118 , the setting data of VHF-H and -L bands in the operation switching signal are retained in the first and second flip-flop circuits  119  and  120  of the data latch circuit  118 . 
     As illustrated in FIG.  5  and Table 2 shown below, the setting data transmitted from normal output terminals of the first and second flip-flop circuits  119  and  120  are inverted into setting data A and B by the first and second integrated injection logic gates  203  and  204 , respectively. The thus obtained setting data A and B are logically multiplied in the wired AND  205 . 
     Then, the thus logically multiplied setting data is inverted into setting data C by a third integrated injection logic gate  206 . The thus obtained setting data C is inverted again into setting data D by a fourth integrated injection logic gate  207 , and the thus produced setting data D is input into the UV switching buffer  104  of the frequency converter  103 . 
     
       
         
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                 VL 
                 VH 
                 U/FM 
                 FM/U 
                   
                   
                   
                   
                 UV 
               
               
                 B1 
                 B2 
                 B3 
                 B4 
                 A 
                 B 
                 C 
                 D 
                 SW 
               
               
                   
               
             
             
               
                 1 
                 0 
                 X 
                 X 
                 0 
                 1 
                 1 
                 0 
                 VHF 
               
               
                 0 
                 1 
                 X 
                 X 
                 1 
                 0 
                 1 
                 0 
                 VHF 
               
               
                 0 
                 0 
                 X 
                 X 
                 1 
                 1 
                 0 
                 1 
                 UHF 
               
               
                 1 
                 1 
                 X 
                 X 
                 0 
                 0 
                 1 
                 0 
                 VHF 
               
               
                   
               
             
          
         
       
     
     Similarly to the tuner integrated circuit  101 , since the tuner integrated circuit  201  in the second embodiment switches a mode of the frequency converter  103  in accordance with the setting data of VHF-L and -H bands in the operation switching signal, it is possible to process the operation switching signals having two kinds of formats, with a single tuner integrated circuit, which ensures a high fabrication yield. 
     Differently from the tuner controller  102  in the first embodiment, in the tuner integrated circuit  201  in the second embodiment, normal outputs transmitted from the first and second flip-flop circuits  119  and  120  of the data latch circuit  118  are inverted by the integrated injection logic gates  203  and  204 , respectively, and then, logically multiplied in the wired AND  205 . 
     Hence, the tuner integrated circuit  201  in the second embodiment has a greater number of elements than that of the tuner integrated circuit  101  in the first embodiment. However, it is no longer necessary to make wirings to be connected to inverted outputs of the first and second flip-flop circuits  119  and  120 . Hence, for instance, a wiring connecting the normal outputs of the first and second flip-flop circuits  119  and  120  to the band switching buffer  124  may be branched, and the thus branched wirings may be connected to the integrated injection logic gates  203  and  204 . This arrangement makes an area occupied by wirings smaller, and a circuit smaller in size. 
     A television tuner in accordance with the third embodiment is explained hereinbelow with reference to FIG.  6 . Parts or elements that correspond to those of the first embodiment illustrated in FIG. 4A have been provided with the same reference numerals and names, and are not detailed. FIG. 6 is a block diagram of a tuner integrated circuit constituting a part of the television tuner in accordance with the third embodiment of the present invention. 
     In a tuner integrated circuit  301  of the television tuner in accordance with the third embodiment, a tuner controller  302  is connected to a frequency converter  103 , similarly to the tuner integrated circuit  101  illustrated in FIG.  4 A. 
     The tuner controller  302  has almost the same structure as that of the tuner controller  102  of the tuner integrated circuit  101 , but is different from the tuner controller  102  in a connection between the data latch circuit  108  and the UV switching circuit  104 . 
     In the tuner controller  302  of the tuner integrated circuit  301  in accordance with the third embodiment, inverted outputs of the first and second flip-flop circuits  119  and  120  of the data latch circuit  118  are connected to a CMOS AND gate  303  acting as a logical multiplier, and the CMOS AND gate  303  is connected to the Lw switching buffer  104  of the frequency converter  103 . 
     The tuner integrated circuit  301  in the third embodiment switches an operation mode of the frequency converter  103  in accordance with the operation switching signals, similarly to the tuner integrated circuit  101  illustrated in FIG.  4 A. 
     As illustrated in FIG.  6  and Table  3  shown below, the setting data A and B transmitted from the inverted output terminals of the first and second flip-flop circuits  119  and  120  are logically multiplied into setting data D by the CMOS AND gate  303 , and the thus obtained logical product as the setting data D is input into the UV switching buffer  104  of the frequency converter  103 . 
     
       
         
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
               
                   
               
               
                 VL 
                 VH 
                 U/FM 
                 FM/U 
                   
                   
                   
                 UV 
               
               
                 B1 
                 B2 
                 B3 
                 B4 
                 A 
                 B 
                 D 
                 SW 
               
               
                   
               
             
             
               
                 1 
                 0 
                 X 
                 X 
                 0 
                 1 
                 0 
                 VHF 
               
               
                 0 
                 1 
                 X 
                 X 
                 1 
                 0 
                 0 
                 VHF 
               
               
                 0 
                 0 
                 X 
                 X 
                 1 
                 1 
                 1 
                 UHF 
               
               
                 1 
                 1 
                 X 
                 X 
                 0 
                 0 
                 0 
                 VHF 
               
               
                   
               
             
          
         
       
     
     The UV switching buffer  104  receives the setting data D defined as mentioned above, and transmits control signals through a control signal wiring in accordance with the received setting data D. An operation mode in the frequency converter  103  is switched between UHF and VHF modes in accordance with the control signals. 
     Similarly to the tuner integrated circuit  101 , since the tuner integrated circuit  301  in the third embodiment switches a mode of the frequency converter  103  in accordance with the setting data of VHF-L and -H bands in the operation switching signal, it is possible to process the operation switching signals having two kinds of formats, with a single tuner integrated circuit, which ensures a high fabrication yield. 
     Differently from the tuner controller  102  in the first embodiment, the inverted outputs of the first and second flip-flop circuits  119  and  120  are logically multiplied by the CMOS AND gate  303  in the tuner integrated circuit  301 . Hence, it is unavoidable that the tuner integrated circuit  301  in the third embodiment has more complicated circuit structure than that of the tuner integrated circuit  101  in the first embodiment. However, the tuner integrated circuit  301  in the third embodiment has a smaller number of circuit elements than that of the tuner integrated circuit  101  in the first embodiment, from the viewpoint of which the tuner integrated circuit  301  could have higher productivity, smaller size, and lighter weight. 
     FIG. 7 partially illustrates a tuner integrated circuit constituting a part of a television tuner in accordance with the fourth embodiment. The illustrated tuner integrated circuit has almost the same structure as that of the tuner integrated circuit  301  illustrated in FIG. 6, but is different from the tuner integrated circuit  301  in further having a first inverter  401  connected to the first flip-flop circuit  119 , and a second inverter  402  connected to the second flip-flop circuit  120 . Normal outputs of the first and second flip-flop circuits  119  and  120  are inverted by the first and second inverters  401  and  402 , respectively. The thus inverted normal outputs are logically multiplied by the CMOS AND gate  303 . 
     The fourth embodiment provides the same advantages of the above-mentioned third embodiment. 
     FIG. 8 partially illustrates a tuner integrated circuit constituting a part of a television tuner in accordance with the fifth embodiment. The illustrated tuner integrated circuit has almost the same structure as that of the tuner integrated circuit  301  illustrated in FIG. 6, but is different from the tuner integrated circuit  301  in that the illustrated tuner integrated circuit includes a CMOS NOR gate  403  in place of the CMOS AND gate  303 . 
     Normal outputs of the first and second flip-flop circuits  119  and  120  are negatively, logically summed by the CMOS NOR gate  403 . The fifth embodiment provides the same advantages of the above-mentioned third embodiment. 
     Hereinbelow is explained an embodiment of a recording medium storing a program therein for accomplishing the above-mentioned television tuners. 
     A recording medium storing a program for accomplishing the above-mentioned television tuners may be accomplished by programming functions of the above-mentioned television tuners with a programming language readable by a computer, and recording the program in a recording medium such as CD-ROM, a floppy disc, a magnetic tape, and any other suitable means for storing a program therein. 
     As a recording medium may be employed a hard disc equipped in a server. It is also possible to accomplish the recording medium in accordance with the present invention by storing the above-mentioned computer program in a recording medium as mentioned above, and reading the computer program by other computers through a network. 
     While the present invention has been described in connection with certain preferred embodiments, it is to be understood that the subject matter encompassed by way of the present invention is not to be limited to those specific embodiments. On the contrary, it is intended for the subject matter of the invention to include all alternatives, modifications and equivalents as can be included within the spirit and scope of the following claims. 
     The entire disclosure of Japanese Patent Application No. 9-266467 filed on, Sep. 30, 1997 including specification, claims, drawings and summary is incorporated herein by reference in its entirety.