JPH0916524A - Display screen automatic background lighting electrical calculator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric calculator capable of automatically controlling the illumination of background light for a liquid crystal display board in accordance with the brightness of a working environment. SOLUTION: In the electric calculator for automatically illuminating background light for a display screen, a keyboard, a microprocessor 2 and a liquid crystal display board in the calculator are connected to an electric circuit, the microprocessor 2 and the display board are provided with a photosensitive switch 41, an exciting power supply 42, an electronic light emitting board 43, and an automatic background light generating element 4 connected to the electric circuit and a photosensitive transistor Q1 in the switch 41 detects the brightness of a working environment.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an improved calculator,
Specifically, it relates to an electric calculator having a function of illuminating the background of a kind of automatically opening and closing display screen.

[0002]

2. Description of the Prior Art Electronic calculators currently on the market do not have the ability to automatically provide background light that illuminates a display screen. Therefore, when working in a place where the illuminance is insufficient or where the illuminance should not be taken, for example, the cockpit and cabin of an airplane, the cockpit of ships and trains, hospitals, laboratories, and occupations that require dark surroundings It is inconvenient to use a calculator in the place of (bar, night club), and there are various problems if it cannot be used.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electric calculator capable of automatically controlling the illumination of the background light of a liquid crystal display panel according to the brightness of the working environment.

[0004]

The present invention will be described below with reference to the drawings. The present invention has been realized as follows. Keyboard, microprocessor 2 connected to electrical circuitry
In addition to the liquid crystal display panel 3, a component 4 for generating automatic background light is included. The component 4 that generates this automatic background light is a photosensitivity switch 41, which includes an excitation power source and an electroluminescent plate 43. This component is connected to the electric circuit. The switch state of the photosensitivity switch 41 is determined by this practical new type calculator depending on the light and dark conditions of the site. When the light is insufficient or the weather is dim, the photosensitivity switch 41 is opened, the excitation power supply is activated, the electronic light emitting plate 43 is caused to emit light, and the liquid crystal display plate 3 is provided with background light. To do. When the brightness is normal, the user can clearly see the numbers displayed on the LCD panel. At that time, the photosensitivity switch 41 is turned off, and the pull-up circuit of the excitation power supply is cut off. In this case,
The electroluminescent plate 43 does not operate, that is, it does not provide background light to the liquid crystal display panel 3.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1, 2 and 3 are views showing an embodiment of the present invention. FIG. 1 shows a flow chart of the electrical circuit structure of the present invention. FIG. 2 shows a principle diagram of an electric circuit of the automatic background light generating component of the present invention. FIG. 3 is a structural conceptual diagram of the present invention. Referring to FIG. 1, an electric calculator according to the present invention includes a keyboard 1 connected to an electric circuit, a microprocessor 2, a display screen 3 including a liquid crystal display panel, and an automatic background light generating component.

Referring to FIG. 2, an automatic background light generating component 4
Is a composite structure including a light sensitive switch 41 connected to an electric circuit, which is a light sensitive transistor Q1 and a resistor R1.
The photosensitivity amplifier 411, the N-P-N type transistor amplifier 412, and the P-N-P type transistor 413 are connected to each other, and the transistor 413 is connected to the power supply circuit of the exciting power source 42. In this way, when the ambient light is bright, the photosensitivity transistor amplifier 411 is turned on, the transistor amplifier 412 is cut off, and the transistor 413 is cut off, so that the power supply current of the excitation power supply 42 is cut off. On the contrary, when the ambient light is insufficient or dim, the photosensitivity transistor amplifier 4
11 does not operate, the transistor amplifier 412 is driven, the transistor Q2 forming the transistor amplifier 412 is turned on, the transistor 413 is driven, and the power supply current of the excitation power supply 42 is operated. Finally, the electroluminescent plate 43 emits light to provide the liquid crystal display panel 3 with background light for illumination.

In this embodiment, the excitation power supply 42 includes an oscillator 412 and a transformer 422 in communication with the electrical circuit. The transistor Q3 in this transformer 421 is NP
A N-type transistor whose emitter is a transformer 42
2 is connected to the center connector of the primary coil, its collector electrode is connected to the power supply through the transistor 413, one terminal of the primary coil 4221 is grounded, and the other terminal is connected to the capacitor C1; The other terminal of the capacitor C1 is connected to the base electrode and the collector electrode of the transistor Q3 separately through the resistors R4 and R3, and the capacitor C2 is jumpered between the collector electrode and the base electrode of the transistor Q3. .

Referring to FIG. 3, the electroluminescent plate 43 is attached to the back of the liquid crystal display plate 3, but the photosensitivity switch 4
The light-sensitive transistor Q1 in the first light-sensitive transistor 41 is attached at an appropriate position where ambient light and dark can be detected. In this embodiment it is mounted on top of the middle of the LCD panel 3. In this case, the display data is not affected and the brightness of the environment of the display board 3 can be reflected. The following are the parameters of the relevant members of this example.

R1 = 150K R2 = 10K R3 = 680Ω R4 = 10K F5 = 4.7K Q1 is a light sensitive triode of PT370 type. C1 = 6.
8μ, C2 = 0.047μ

[0010]

EFFECTS OF THE INVENTION As described above, the present invention: 1) Expands the use range of the calculator so that it can be normally used even when working in a place where there are insufficient rays or where the rays should not be sufficiently bright. it can. 2) It is convenient to use, and even if the light and shade of the light beam changes at the site of use, it does not prevent the user from continuing the calculation.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining the principle of the present invention.

FIG. 2 is a circuit diagram showing a connection relationship between an electric circuit of an automatic background light generation component and an IC.

FIG. 3 is a structural conceptual diagram of the present invention.

[Explanation of symbols]

 1 keyboard 2 microprocessor 3 display screen 41 light sensitivity switch

Front Page Continuation (72) Inventor Wong Pong Chun Hong Kong New Territories Kwai Chun Wing Yip Street 1-3 Chun Shun Knitting Center Second Floor

Claims (4)

[Claims] 1. A keyboard (1), a microprocessor (2) and a liquid crystal display panel (3) of an electric calculator are connected to an electric circuit so that the microprocessor (2) and the liquid crystal display board (3) of the electric calculator are connected. ) Is provided with a photosensitivity switch (41), an excitation power source (42), an electronic light emitting plate (43), and an automatic background light generating component (4) connected to an electric circuit, and behind the liquid crystal display plate (3). An automatic electricity calculator for background light of a display screen, characterized in that an electroluminescent plate (43) is provided, and a light sensitive transistor Q1 of the light sensitive switch (4) detects the brightness of the environment. 2. A resistor R as the photosensitivity switch (41)
1 and a photosensitivity transistor Q1 to form a photosensitivity transistor amplifier (411), and an NPN type transistor amplifier (412) and a PNP type transistor (413) to construct a composite switch structure. An automatic electricity calculator for the background light of a display screen according to claim 1. 3. Automatic display screen according to claim 1, characterized in that the excitation power supply (42) comprises an oscillator (421) and a transformer (422) connected to a power supply circuit. Background light lighting electrical calculator. 4. An automatic electricity calculator for background light of a display screen according to claims 1 and 2, characterized in that the light sensitive transistor Q1 is mounted on a liquid crystal display panel (3).