JPH0228228B2 - TEIATSUHODENTOOYOBISONOSEIGYOHOHO - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a low-pressure discharge lamp, such as a fluorescent lamp, whose light color and luminous flux can be freely changed, and a method of controlling the same.

(Background Art) As a color discharge lamp and its control method that can freely select and control the light color, we previously proposed a lamp and basic control circuit as shown in Figures 1 and 2 (Japanese Patent Application No. 131593/1982) ).

A discharge space 3 airtightly formed by an outer tube 1 and a stem 2 is filled with several Torr of rare gas and mercury vapor. It houses three U-shaped inner tubes 4a, 4b, 4c of approximately the same shape coated with a phosphor of electrodes 5a, 5
b and 5c, respectively, and the other end 6 is arranged to open near another common electrode 7 arranged on the stem 2.

The lighting circuit shown in FIG. 2 includes the above-mentioned discharge lamp FL,
A series circuit consisting of a discharge path selection switch Sw and a current-limiting variable resistor VR is operated by a DC power supply Vs. The discharge path selection switch Sw is operated to sequentially switch the discharge of the three inner tubes 4a, 4b, and 4c, as shown in the time chart of FIG. In other words, the period T is the three inner tubes 4a, 4
Each inner tube 4a, 4b, 4c is divided into light emitting periods b and 4c and the ratio of the light emitting periods is changed.
By changing the ratio of the emitted luminous flux, the emitted color (mixed color)
It changes the In addition, in the time chart shown in FIG. 3, an example is shown in which T1 is white, T2 is white-yellow, and T3 to T4 are yellow. Also, if the period T is set to about 10ms, each inner tube 4
A, 4b, and 4c appear to be lit at the same time.

Although such a variable color discharge lamp device has a plurality of discharge paths, only one current-limiting impedance is required, which is advantageous in terms of cost and miniaturization. Since the circuit current remains approximately constant even when the current is changed, the common electrode 7 is always kept at an appropriate temperature, which reduces the lifespan and response to changes in luminescent color compared to the case where three fluorescent lamps with different luminous colors are individually dimmed. However, because the luminous flux (luminance) is controlled by a current-limiting variable resistor VR, the response speed to changes in luminous flux is slower than the response speed to changes in luminescent color. . Furthermore, when controlling the luminous flux using a variable resistor, the current is changed, which has the disadvantage that the feature of this device, which is that the circuit (cathode) current is constant, is lost.

(Object of the invention) The present invention has been made in view of the above problems, and
The purpose is to provide a low-pressure discharge lamp and a control method thereof that have sufficiently fast response while keeping the circuit (cathode) current constant.

(Disclosure of the Invention) FIG. 4 shows an embodiment of the low-pressure discharge lamp according to the present invention, which differs from the conventional example shown in FIG. 1 in that an auxiliary electrode 8 is provided on the stem 2. , and other configurations are the same, so the description will be omitted by assigning the same reference numerals to the equivalent configurations.

FIG. 5 shows an example of a basic circuit for lighting the fluorescent lamp according to the above embodiment, and the circuit shown in FIG.
The auxiliary electrode 8 is connected to the discharge path selection switch Sw via a resistor r (which may be zero), and together with the other three discharge paths, there are four discharge path selection switches Sw. An example of a time chart for switching the discharge path selection switch Sw is shown in FIG. In the same figure, T1 and T2 are three inner tubes 4 as in the conventional case.
a, 4b, and 4c emit light evenly, resulting in a substantially white state. From T3, a discharge period (1/3) T is provided for flowing through the auxiliary electrode 8, and by providing such a discharge period, the luminous flux becomes approximately 2/3 of the luminous flux from T1 to T2. . In other words, the discharge flowing through the auxiliary electrode 8 does not contribute to the light emission of the lamp FL, and by appropriately setting the discharge period, a desired luminous flux can be obtained.

In this way, by controlling light (luminous flux adjustment) by flowing a discharge current that does not contribute to light emission, the circuit current can be kept approximately constant even if the luminous flux is changed, so unlike conventional lamps, the lamp life may be adversely affected. Moreover, since the luminous flux is adjusted by switching the discharge path, the responsiveness is comparable to that of changing the hue. Furthermore, regarding control, the control method is exactly the same as that for switching the discharge paths of the three inner tubes 4a, 4b, and 4c, which is advantageous in terms of circuit configuration.

In the above embodiment, the auxiliary electrode 8 was provided on the stem 2, but the present invention is not limited thereto.Furthermore, in order to clarify the discharge characteristics from the auxiliary electrode 8, fluorescent light was provided on the stem 2. A fourth inner tube which does not apply the body may be provided, and each inner tube 4a, 4
It goes without saying that the shapes of b and 4c are not limited to the U-shape, and may be straight pipes, for example, and the number of inner pipes does not need to be three.

Next, an embodiment in which the auxiliary electrode 8 is used not only for adjusting the luminous flux but also for starting will be described based on the circuit diagram shown in FIG. In this embodiment, the non-power side terminal of the common electrode 7 and the auxiliary electrode 8 are added to the circuit shown in FIG.
and is connected by a resistor Rf, and at the time of starting, the discharge path selection switch Sw is connected to the auxiliary electrode 8,
DC power supply Vs - Resistor R - Discharge path selection switch Sw -
The filament constituting the common electrode 7 is preheated through a path of resistance r - resistance Rf - common electrode 7 - DC power supply Vs. When the filament is sufficiently preheated,
Due to the potential difference generated across the resistor Rf, a discharge occurs between the common electrode 7 and the auxiliary electrode 8, and starting is completed. The operation after startup is as described above. In this case, it is desirable that the auxiliary electrode 8 be located near the common electrode 7 in order to facilitate starting.

In this way, this embodiment does not require any additional starting circuit, and is extremely advantageous in terms of cost. Note that in this embodiment as well, there are no restrictions on the shape or number of inner tubes.

(Effects of the Invention) As described above, the present invention provides an auxiliary electrode in the discharge space, and by passing a discharge current that does not contribute to light emission through the electrode to perform dimming (luminous flux adjustment), even if the luminous flux is changed, the circuit remains unchanged. The current can be kept almost constant. Therefore, unlike the conventional method, there is no adverse effect on the lamp life, and since the luminous flux is adjusted by switching the discharge path, it has the same level of responsiveness as when changing the hue.

[Brief explanation of drawings]

FIG. 1 shows a fluorescent lamp according to a conventional example, in which a is a perspective view, b is a plan view, FIG. 2 is a basic control circuit according to the conventional example, FIG. 3 is a time chart of the same, and FIG.
The figure shows an embodiment of the low pressure discharge lamp according to the present invention,
5 is a basic control circuit example according to the present invention, FIG. 6 is a time chart of the same as above, and FIG. 7 is a different example of a control circuit according to the present invention. 1...Outer tube, 2...Stem, 3...Discharge space,
4...Inner tube, 5...Electrode, 7...Common electrode, 8...
...Auxiliary electrode.

Claims (1)

[Claims] 1. Several Torr of rare gas and mercury vapor are sealed in a discharge space airtightly formed by an outer tube and a stem, and one end is placed around each of a plurality of electrodes arranged on the stem. A low-pressure discharge lamp comprising a plurality of inner tubes each of which is airtightly fixed and whose other end opens into the discharge space, each forming a discharge path with a common electrode disposed within the discharge space. A low-pressure discharge lamp characterized in that an auxiliary electrode is disposed within the discharge space. 2. The low-pressure discharge lamp according to claim 1, wherein each of the plurality of inner tubes is coated with a phosphor that emits light of a different color. 3. Claim 1 or 2, characterized in that the auxiliary electrode is disposed near the common electrode.
Low-pressure discharge lamps as described in section. 4 Airtightly formed by the outer tube and stem, with several
In a discharge space filled with Torr rare gas and mercury vapor, one end is hermetically fixed around each of the plurality of electrodes arranged on the stem, and the other end is opened into the discharge space. Along with installing the pipe,
In a low-pressure discharge lamp having a common electrode and an auxiliary electrode, each of the plurality of electrodes and the auxiliary electrode are sequentially switched, the discharge time ratio with the common electrode is controlled, and the light color and luminous flux are controlled. A method for controlling a low-pressure discharge lamp, characterized by: