JPH0245999Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a fluorescent light stand with a built-in radio.

Conventionally, in a discharge lamp lighting device that performs high-frequency lighting, in order to remove the switching nozzle that occurs in the high-frequency generation circuit that generates high frequencies, the device is housed in a shield case to prevent the switching nozzle from leaking to the outside. It was.

However, the nozzle coming out of a discharge lamp that discharges at high frequency cannot be removed because Sealad cannot be applied.
There was a problem in that the nozzle generated by the discharge lamp affected radios, etc., and in particular generated harsh beat sounds from radios. In order to prevent this beat sound from occurring, it was necessary to install the radio and the discharge lamp several meters apart.

On the other hand, high-frequency lighting has the advantage of being bright and flickering-free, and when used in fluorescent light stands, reduces eye fatigue.

However, due to the above-mentioned drawbacks, it is not suitable for use as a fluorescent lamp stand with a built-in radio, and furthermore, there is a problem that a radio cannot be used on the same desk due to the so-called ``nagara group''.

In view of this point, the present inventor considered the generation process of the above-mentioned beat sound and found the following.

FIG. 1 shows a schematic block diagram of a fluorescent lamp lighting device using a conventional high frequency generating circuit, and the fluorescent lamp lighting device performs the following operations. In other words, commercial power supply 1
is rectified and smoothed by the full-wave rectifier 5 and smoothing capacitor 6 of the DC power supply unit 2 and converted to DC, and the separately excited or automatic high frequency generation circuit 3 is driven by this DC,
The fluorescent lamp 4 is turned on by applying the high frequency output from the high frequency generating circuit 3 to the fluorescent lamp 4 via the current limiting element.

The output voltage of the DC power supply section 2 of this conventional example circuit includes a ripple with a frequency component twice the frequency of the commercial power supply 1 because the smoothing capacitor 6 is charged every half cycle of the commercial power supply frequency, and its waveform is Figure 2a
It's becoming like that. Further, the lamp current Ia flowing through the fluorescent lamp 4, which is lit by the high frequency output of the high frequency generating circuit 3 driven by the output of the DC power supply section 2, has a waveform as shown in FIG. 2b. This lamp current I
Looking at the envelope of the peak value of a, it can be seen that a waveform equivalent to the output waveform of the DC power supply section 2 is generated. Since the lamp current Ia flows at the oscillation frequency shown in FIG. 2b, the noise from the fluorescent lamp 4 is generated by a harmonic nozzle having an integral multiple of the oscillation frequency.

By the way, in the radio that generates the beat sound (for AM of a superheterodyne receiver), as shown in FIG. After converting the reception frequency to 455KHz in the frequency conversion circuit 8, amplification and detection are performed in the intermediate frequency amplifier circuit 10 and the detection circuit 11. For example, when the carrier frequency is 1000KHz, modulation is performed at a low frequency such as music. In the case of broadcast reception, the oscillation frequency of the local oscillation circuit 9 is set to 1455KHz according to the tuning frequency of the high frequency amplifier circuit 7, and the difference frequency is set to 1455KHz.
After obtaining 455KHz with frequency conversion circuit 8, amplify it,
The low frequency signal is detected by the detection circuit 11 and reproduced by the low frequency amplification circuit 12 and the speaker 13.
Therefore, the present inventor investigated the frequency of the detection output of the beat sound generated from the radio when high frequency lighting was performed, and found that the frequency was twice the frequency of the commercial power supply 1. In other words, the harmonic of the oscillation frequency of the high frequency generation circuit 3 becomes a carrier wave, the ripple frequency included in the output of the DC power supply section 2 becomes a low frequency signal, causing the same phenomenon as amplitude modulation, and the tuning frequency of the radio becomes the harmonic. It was discovered that a beat sound is generated when the If the oscillation frequency of the high frequency generation circuit is, for example, 80KHz as shown by the line in Figure 4, the generated harmonics will be 560KHz, 640KHz, 720KHz, 800KHz, and 880KHz in the AM reception band (525KHz to 1605KHz).
Hz, 960KHz, 1040KHz, 1120KHz, 1200KHz,
1280KHz, 1360KHz, 1440KHz, 1520KHz,
Occurs at 1600KHz.

Figure 4 shows the relationship between this harmonic and the change in tuning frequency within the tuning range of the radio. It will emit noise at the tuned frequency that intersects the line indicating the frequency of .

The present invention was devised in view of these points, and its purpose is to prevent the beat sound from being affected by the high frequency generation circuit during radio reception, and to combine the radio and the high frequency generation circuit. To provide a fluorescent light stand that can be incorporated into the.

The present invention will be explained below using examples.

FIG. 5 shows a circuit diagram of an embodiment of the present invention. The high frequency generation circuit 3 is composed of a two-stone ringing chain type inverter circuit.
In this high frequency generation circuit 3, when the power is turned on, one of the transistors Tr ₁ and Tr ₂ starts switching operation by the starting resistor R ₁ , and this causes positive feedback from the base feedback winding Nb of the oscillation transformer OT. is applied and the base bias winding Nc
Self-excited oscillation is started by the base current obtained by rectifying and smoothing the output of the oscillation transformer.
The high frequency output output from the output winding No. of the OT is applied to the fluorescent lamp 4 via the chi York CH to maintain lighting. Note that the starter is omitted in the figure. By the way, the oscillation frequency of this high frequency generation circuit 3 during lighting is determined by the value of the resonance capacitor C ₀ connected in parallel with the primary winding Na of the oscillation transformer OT.
By changing this value, the oscillation frequency can be varied.

Therefore, if capacitor C ₀ is made a variable capacitor,
Change the value of capacitor C ₀ corresponding to the tuning frequency,
In this embodiment, the harmonics of the oscillation frequency of the high frequency generation circuit ₃ and the tuning frequency are not made to match. a variable capacitor C ₂ that changes the value, and the above capacitor C ₀
variable capacitors C ₁ and C ₂ so that
The operating shaft is mechanically connected to the operating shaft of the radio frequency generating circuit 3, and the capacitor _C0 of the high frequency generating circuit 3 is used to vary the oscillation frequency of the high frequency generating circuit 3 in accordance with the operation of the radio station selection knob. The capacitance change is set in advance so that the harmonics of the high frequency generation circuit 3 do not match the tuning frequency at each point in accordance with the change in the tuning frequency. Figure 6 shows a high frequency generation circuit 3 that changes the tuned tuning frequency as shown by line A within the tuning range of the radio.
The graph shows the changes in the harmonics C, D, H, etc. of an embodiment in which the oscillation frequency of is changed as shown by the line B, and the line A of the tuning frequency change is n times the oscillation frequency of the high frequency generation circuit 3. If the oscillation frequency is changed as shown by line B between the n+1 times higher harmonics C and D, the frequency of the harmonics will not be equal to the tuning frequency.

In this way, in this embodiment, the high frequency amplifier circuit 7
and variable capacitors C ₁ and C ₂ of local oscillation circuit 9
The oscillation frequency of the high frequency generation circuit 3 is varied by mechanically interlocking with the value of the capacitor _C0 of the high frequency generation circuit 3, so that the tuning frequency of the radio and the harmonics of the oscillation frequency do not match, and the DC power supply section 2 This makes it possible to prevent the detection and reproduction of the beat sound by the ripple component from being carried out on the radio side.

FIG. 7 shows an embodiment in the case of a separately excited high frequency generation circuit 3. In this case, an oscillation circuit 15 for generating a trigger signal of the switching section 14 of the high frequency generation circuit 3 is used.
The capacitor C ₀ ' for setting the frequency is made variable, and the oscillation frequency is changed by mechanically interlocking the capacitor C ₀ ' with the tuning operation on the radio side, as in the above embodiment. T ₀ is an output transformer.

In each of the above embodiments, the oscillation frequency is made variable by changing the capacitance of the capacitor _C0 of the high frequency generation circuit 3 through mechanical interlocking, but this may also be done electrically or with a coaxial configuration. Instead, an interlocking configuration using a belt may be used.

FIG. 8 is a schematic circuit block diagram for changing the oscillation frequency of the high frequency generating circuit 3 electrically. In other words, there is a local oscillation frequency detection circuit 16 that detects the local oscillation frequency leaking from the local oscillation circuit 9 of radio A, a tuning frequency that is detected based on the signal detected by the circuit 16, and a high frequency generation circuit 3 that detects the tuning frequency based on the signal detected by the circuit 16. Control processing circuit 1 that varies frequency
7 may be provided.

In this case, first, the control processing circuit 17 controls the frequency variable means of the high frequency generation circuit 3 to vary the oscillation frequency within a range of, for example, ± several KHz, and the local oscillation frequency detection circuit 16 generates a high frequency together with the local oscillation frequency of the radio A side. The harmonics of the oscillation frequency of the circuit 3 are detected and the frequency components are analyzed by the control processing circuit 17 to determine whether there is a frequency that does not change in the detection signal. If there is a frequency that does not change, that frequency is the local oscillation frequency of radio A, so the high frequency generation circuit 3 calculates the tuning frequency from this local oscillation frequency and does not include the tuning frequency as a harmonic.
The control processing circuit 17 obtains the frequency in advance through experiments etc.
The frequency variable means of the high frequency generation circuit 3 is controlled so as to select the frequency from data stored in the frequency generator 3 and the frequency is selected from data stored in the frequency generator 3. On the other hand, if there is no change in the frequency change determination, the control processing circuit 17 further controls the frequency variable control means of the high frequency generation circuit 3 so as to widen the range of change in the oscillation frequency of the high frequency generation circuit 3. At the same time, the local oscillation frequency detection circuit 16 is controlled to increase the detection sensitivity of the local oscillation frequency detection circuit 16.

In this way, in this embodiment, the high frequency generating circuit 3
The current tuning frequency of radio A is detected by changing the oscillation frequency of the radio A, and the oscillation frequency of the high frequency generation circuit 3 is controlled with respect to this detected tuning frequency so that the harmonics are not the same as the tuning frequency, and the above-mentioned This prevents the generation of beat sounds. FIG. 8 shows a flowchart of the above-described operation of this embodiment. Furthermore, the frequency variable means of the high frequency generation circuit 3 may be a mechanical capacitance variable means, a variable capacitance element made of a semiconductor, or electronically changing a circuit constant that can vary the oscillation frequency. Means may also be used.

The present invention provides a high frequency generation circuit with a means for varying the oscillation frequency, and operates the variable means in accordance with the tuning frequency set on the radio for AM reception, so that the harmonics of the oscillation frequency of the high frequency generation circuit become the tuned frequency. Since it is equipped with an interlocking means that sets the values so that they are not equal, the harmonic components of the oscillation frequency of the high frequency generation circuit, amplitude modulated by the ripple component contained in the DC obtained by rectifying the commercial power supply, are received by the radio. As a result, it is possible to prevent the generation of beat sound from the radio due to the ripple component which is the modulation component, and since the generation of beat sound is eliminated, the radio and the high frequency generation circuit are integrated. In addition, the low-flicker lighting that is a feature of the high-frequency generator circuit makes it possible to create a stand that reduces eye fatigue, and since it can be integrated with a radio, it does not take up much space on your desk. , it has the advantage of being very convenient to handle for the so-called ``Nagagazoku''.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a fluorescent lamp lighting device using a conventional high-frequency generating circuit, FIGS. Fig. 4 is an explanatory diagram showing the relationship between the change in tuning frequency and harmonics in the same as above, Fig. 5 is a circuit block diagram of an embodiment of the present invention, and Fig. 6 is a variable capacitor C ₀ used in the same as above. 7 is a circuit block diagram of another embodiment of the present invention, FIG. 8 is a circuit block diagram of another embodiment of the present invention, and FIG. 9 is a flowchart for explaining the operation of the same. 1 is a commercial power supply, 2 is a DC power source, 3 is a high frequency generation circuit, 4 is a fluorescent lamp, and C ₀ is a capacitor.

Claims (1)

[Scope of utility model registration request] It is equipped with a high-frequency generation circuit that generates high-frequency output using direct current obtained by rectifying a commercial power source, and lights a fluorescent lamp with the high-frequency output. The circuit is provided with an oscillation frequency variable means, and the variable means is operated in accordance with a tuning frequency set by the radio placed near the high frequency generation circuit, so that the harmonics of the oscillation frequency of the high frequency generation circuit are tuned. 1. A fluorescent lamp stand comprising interlocking means for setting the frequency so that it is not equal to the frequency.