JPH05283006A - Luminance adjusting method and luminance unevenness detecting device - Google Patents

Abstract

PURPOSE:To enable visual judgement of a luminescent element which causes luminance unevenness in a group of luminescent elements. CONSTITUTION:A luminescent element A which excites and brightens a phosphor 9 applied to the anode face by accelerating thermions from a cathode 2 and hitting them against an anode in a vacuum container 1 is provided. The cathode voltage in a temperature limited region is applied to the cathode 2 of each luminescent element A of a group of luminescent elements 22 where a plurality of luminescent elements A are installed side by side from a cathode power source 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brightness adjusting method and a brightness unevenness detecting device for detecting the brightness unevenness of each light emitting element forming a pixel of a large screen display device and making the detection result available for a brightness adjusting operation. It is a thing.

[0002]

2. Description of the Related Art FIG. 3 is an exploded perspective view showing a conventional light emitting device disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) No. 62-10849, wherein 1a is a display member coated with a phosphor 9, and 1b is a display member. Spacers 1c are substrates (rear panels) on which various control electrodes are arranged. These are combined as shown in FIG. 4 to form the vacuum container 1 of the display tube.

2 is a linear cathode, 3 is a first control electrode (scan electrode), 4 is a second control electrode (data electrode),
Reference numerals 5 and 6 are wiring patterns for commonly connecting the control electrodes 3 and 4 in the row direction and the column direction, 7 is a shield electrode provided with an opening corresponding to the light emitting portion, and 8 is provided on the shield electrode 7. The opening 10 is an exhaust unit. Further, an aluminum thin film is vapor-deposited on the phosphor 9 in order to improve the luminous efficiency.

FIG. 5 is a wiring diagram showing the arrangement and wiring of the two types of electrodes 3, 4. S1 to S4 are lead portions of the scan electrodes 3 commonly connected in the row direction, and D1 to D4 are lead portions of the data electrodes 4 commonly connected in the column direction.

FIG. 6 is a timing chart of signals applied to the respective electrodes, FIG. 7 is an explanatory diagram showing a correspondence relationship between the pixel array and the electrodes, and FIG. 8 is a potential of each electrode and a flow of electrons. 9A and 9B are front views of a display in which a plurality of light emitting elements are arranged.

Next, the operation will be described. The basic principle of this type of display device is that the thermoelectrons emitted from the cathode 2 are accelerated and collide with the anode to excite the phosphor 9 coated on the anode surface to emit light. That is, in FIG. 7, the thermoelectrons emitted from the cathode 2 behave as follows depending on the combination of the potentials of the scanning electrode 3 and the data electrode 4.

The scan electrodes 3 connected in the row direction and the data electrodes 4 connected in the column direction are both cathodes 2.
On the other hand, when positive, the electrons emitted from the cathode 2 by the positive potential of the data electrode 4 are deflected by the potential of the scanning electrode 3, pass through the predetermined opening 8 and reach the anode, and emit the phosphor 9. Excuse me.

When the scanning electrode 3 is positive and the data electrode 4 is negative, the negative potential of the data electrode 4 near the cathode 2 causes the potential near the cathode 2 to be negative, and the emission of thermoelectrons is suppressed. Therefore, the phosphor 9 does not emit light.

When the scan electrode 3 is negative and the data electrode 4 is positive, there are the following two cases. a When the other scanning electrode 3 is positive, the thermoelectrons emitted from the cathode 2 are deflected to the other scanning electrode 3 side by the potential of the scanning electrode 3, and the phosphor 9 does not emit light.

B If the other scanning electrode 3 is also negative, the potential of the data electrode 4 is positive, but since the area of the data electrode 4 is small, due to the influence of the negative potential of the scanning electrodes 3 on both sides,
The vicinity of the cathode 2 becomes negative, and the phosphor 9 in which the emission of thermoelectrons is suppressed does not emit light.

When both the scan electrode 3 and the data electrode 4 are negative, the potential in the vicinity of the cathode 2 becomes negative, the emission of thermoelectrons is suppressed, and the phosphor 9 does not emit light. As a result, FIG.
7 and the arrangement of the pixels in FIG. 7, the phosphors 9 located at the intersections of the scanning electrodes 3 in the rows and the data electrodes 4 in the columns to which a positive potential is applied emit light.

[0012] First, when a signal is applied to the lead-out portion S1, the fluorescent portions P11 to P14 are selected, and these emit light according to the potentials of the lead-out portions D1 to D4 of the data electrode 4. Next, when a signal is applied to the lead-out portion S2, the fluorescent portions P21 to P24 are selected, and light is emitted according to the potentials of the lead-out portions D1 to D4 of the data electrode 4 as well.

In this way, each lead-out portion S1 of the scanning electrode 3 is formed.
6 to S4 and a data signal is applied to any of the lead portions D1 to D4 of the data electrode 4, an arbitrary display can be obtained.

FIG. 9 shows a display in which a plurality of light emitting elements A are arrayed, and the light emitting elements are arranged between pixels (between phosphors) in each light emitting element A so that the connection between the light emitting elements A is inconspicuous. 2 of dead space (width T1) around A
The space T2 more than double is required. The check of the light emission brightness of the light emitting element A is performed by turning on the light after assembling each light emitting element A.

[0015]

Since the conventional light emitting device is constructed as described above, in order to form a large-screen display, there is uneven brightness between the respective devices in which a large number of such light emitting devices are arranged. It is necessary to make adjustments so that the amount of light is less than a certain limit before shipping. Therefore, conventionally, the brightness of each light emitting element was increased, and the unevenness of brightness was visually identified. By removing it and replacing it with another,
The brightness adjustment work must be performed to adjust the brightness of the entire screen, and there is a problem in that the above-described visual unevenness discrimination and brightness adjustment work impose a heavy burden on the operator.

The invention of claim 1 has been made in order to solve the above-mentioned problems. According to the result of discrimination of the unevenness of brightness, the brightness of the light emitting element can be adjusted so as to eliminate the unevenness of brightness. Aim to get a way.

Further, according to the second aspect of the present invention, the unevenness of the luminance can be easily discriminated by lowering the potential of the cathode emitting the thermoelectrons to the level of the temperature limiting region, and the luminance adjustment work based on the discrimination result can be switched. It is an object of the present invention to obtain a brightness unevenness detection device that can be easily performed by one-touch operation.

[0018]

According to a first aspect of the brightness adjusting method of the present invention, a phosphor coated on the anode surface is formed by accelerating thermoelectrons from the cathode in a vacuum container to collide with the anode. While observing the brightness of each light-emitting element, a plurality of light-emitting elements for exciting and emitting light are arranged in parallel, and the cathode voltage in the temperature-limited region is applied to the cathode of each light-emitting element in this arranged light-emitting element group. The brightness of each of these light emitting elements is adjusted.

In the brightness nonuniformity detection device according to the invention of claim 2, the thermoelectrons from the cathode are accelerated in the vacuum container to collide with the anode to excite the phosphor coated on the anode surface to emit light. A light emitting element is provided, and the normal rated lighting state and the lighting state in the temperature limited area are instantly switched from the cathode power source to the cathode of each light emitting element of the light emitting element group in which a plurality of the light emitting elements are arranged in parallel with one touch. The cathode voltage is applied via a switch.

[0020]

According to the brightness adjustment in the first aspect of the invention, the light emitting element having an abnormal brightness is replaced with a light emitting element having a normal brightness to make the brightness uniform, or the brightness provided for each light emitting element according to the result of the brightness unevenness determination. This is performed by adjusting the adjusting unit to balance the brightness of the entire light emitting element group.

Further, in each light emitting element of the light emitting element group according to the invention of claim 2, the anode current ratio is made extremely large by applying a voltage in the temperature control region from the cathode power supply to the cathode by switching the changeover switch. This makes it easier to identify whether the light emitting state is normal or abnormal.

[0022]

EXAMPLES Example 1. An embodiment of the inventions of claims 1 and 2 will be described below with reference to the drawings. In FIG. 2, 21A, 2
1B is a cathode characteristic curve for each light-emitting element A.
A shows a cathode characteristic of a normal light emitting element, and 21B shows a cathode characteristic of an abnormal light emitting element. The vertical axis represents the current Ip flowing to the anode due to thermoelectrons emitted from the cathode 2, and the horizontal axis represents the cathode voltage Vf.

Further, V is a rated cathode voltage during the rated operation, and the anode current of the normal light emitting element at this time is IA, and the anode current of the abnormal light emitting element is IB. Similarly, the anode current of a normal light emitting element is IA (1/2) and the anode current of an abnormal light emitting element is IB (1/2) when the cathode voltage is 1/2 V which is 1/2 of the rated operation. To do. 2 of rated voltage
The same notation is applied to the case of 3.

Generally, in the case of a normal light emitting element, when the rated cathode voltage is V, there is a threshold value at which the anode current Ip starts to flow near 1/2 V, and the anode current Ip increases sharply as the cathode voltage is increased. FIG. 2 shows this state. This steeply rising region is called a temperature limiting region α, which is in the range of approximately 1/2 to 2/3 of the rated voltage V. On the other hand, if the cathode voltage is increased above the temperature limit region α, the increase of the anode current Ip will be gradual. This region is called a space charge limiting region β, and the rated cathode voltage V is in this region β.

As can be seen from FIG. 2, since there is a rated cathode voltage V in the space charge limiting region β, the anode current Ip at the rated cathode voltage V varies depending on whether the light emitting element is normal or abnormal. So there is no big difference. That is, the ratio IA / IB of the anode currents at the rated voltage of the normal light emitting element and the abnormal light emitting element is almost 1 and never doubles or more.

Therefore, as long as the brightness is adjusted with the rated cathode voltage V, it is difficult to distinguish between a normal light emitting element and an abnormal light emitting element. However, if the cathode voltage is dropped to 1/2 to 2/3 of the rated value and the ratio of the anode currents is checked in the same manner, IA (1/2) / IB (1/2) or IA (2 /
3) / IB (2/3) is significantly larger than 1, and it becomes easy to distinguish between a normal light emitting element and an abnormal light emitting element.

Next, a brightness unevenness detecting device constructed based on the above idea will be described. In FIG. 1, 22 is a light emitting element group in which 16 light emitting elements A are arranged side by side, 23 is a cathode power source with a rated cathode voltage, and 24 is a cathode power source adjusted to 1/2 to 2/3 of the rated cathode voltage V. Each of the cathode power supplies 23, 24 is shown to have a rated cathode voltage V that is easily switched to the normal rated lighting state by the changeover switch 25 and about 1 of the rated cathode voltage V that is switched to the lighting state in the temperature limited region. / 2 to 2/3
The state can be switched to.

Next, the operation will be described. First, when the changeover switch 25 is switched to the cathode power supply 23, as described above, 16 light emitting elements A can be made to emit light at the rated cathode voltage V at a time. On the other hand, by switching to the cathode power supply 24, it becomes possible to emit light in a state of about 1/2 to 2/3 of the rated cathode voltage V. At this time, each light emitting element 1
The difference in brightness becomes clear, and the normal light-emitting element A and the abnormal light-emitting element A can be instantly visually distinguished without using an expensive luminance measuring device.

Next, the light-emitting element A whose brightness is determined to be abnormal in this way is replaced with another normal light-emitting element to make the brightness of the entire light-emitting element group uniform or, if necessary, By performing the brightness adjustment by the adjustment operation of the brightness adjustment unit provided for each light emitting element A, the uneven brightness is eliminated,
The luminance balance of the entire light emitting element group can be maintained well.

In the above embodiment, 16 light emitting elements A are used.
The case of the light emitting element group 22 in which the
The number is not limited to 16, and an appropriate number can be used, and the same effect as that of the above-described embodiment can be obtained. Further, in each of the above-mentioned embodiments, the cathode voltage is set to 1/2 to the rated cathode voltage.
The case where 1/3 is selected is shown, but the cathode voltage near the point where the anode current rises sharply (in the temperature limit region)
Can be arbitrarily selected.

[0031]

As described above, according to the first aspect of the invention, by applying the cathode voltage in the temperature limited region to the cathode of the light emitting device, the brightness of each light emitting device can be checked while checking the brightness. Since the brightness of each light emitting element is adjusted, there is an effect that the brightness adjustment work and the brightness unevenness adjustment work can be performed quickly and easily.

According to the second aspect of the invention, a light emitting element is provided which accelerates and emits the phosphor coated on the anode surface by accelerating thermoelectrons from the cathode and colliding with the anode in the vacuum container. To the cathode of each light emitting element of the light emitting element group in which a plurality of the light emitting elements are arranged in parallel, the cathode voltage via the changeover switch that instantly switches between the normal rated lighting state and the lighting state in the temperature limited area with one touch. Since the anode current ratio can be made extremely large, the luminance difference becomes large, and the normal light emitting element and the abnormal light emitting element can be easily distinguished by the simple operation of the changeover switch. , There is an effect that something that can be done visually is obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a brightness adjustment method and a brightness unevenness detection device according to an embodiment of the inventions of claims 1 and 2. FIG.

FIG. 2 is a cathode characteristic curve showing an anode current-cathode voltage of the light emitting device according to the invention of claims 1 and 2.

FIG. 3 is an exploded perspective view showing a conventional light emitting device.

FIG. 4 is a perspective view showing a conventional light emitting device.

5 is a wiring diagram showing an electrode arrangement of the light emitting element in FIG.

6 is a timing chart showing signals applied to each scan electrode and data electrode in FIG.

FIG. 7 is an explanatory diagram showing a correspondence relationship between an array of pixels of the light emitting element in FIG. 3 and electrodes.

8 is an operation explanatory diagram showing the potential of each electrode and the flow of electrons in FIG.

9 is a front view showing a display in which the light emitting elements of FIG. 4 are arranged in parallel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vacuum container 2 Cassault 9 Phosphor 22 Light emitting element group 23, 24 Cathode power supply 25 Changeover switch A Light emitting element

Front page continuation (72) Inventor Shigeki Kikuta 700 Wada, Ueno-machi, Ise City, Mie Prefecture, Ise Electronics Industry Co., Ltd. (72) Norihisa Hasegawa 700 Wada, Ueno-cho, Ise City, Mie Prefecture, Ise Electronics Industry Co., Ltd.

Claims (2)

[Claims] 1. A plurality of light-emitting elements are arranged in parallel in a vacuum container, in which thermoelectrons from the cathode are accelerated to collide with the anode to excite the phosphor coated on the anode surface to emit light. A brightness adjusting method in which the brightness of each light emitting element is adjusted while the brightness of each light emitting element is being observed by applying a cathode voltage in the temperature limited region to the cathode of each light emitting element of the light emitting element group. 2. A light-emitting element for accelerating thermoelectrons from the cathode and colliding with the anode in a vacuum container to excite the phosphor coated on the anode surface to emit light, and a plurality of the light-emitting elements are arranged in parallel. And a cathode for applying a cathode voltage to a cathode of each light emitting element of the light emitting element group through a changeover switch that instantly switches between a normal rated lighting state and a lighting state in a temperature limited region with one touch. An uneven brightness detecting device having a power supply.