JPH09218659A - Electroluminescence display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce variation of brightness of electroluminescence caused by voltage variation of a battery by providing a voltage stabilizing circuit between a boosting driver and a power source battery. SOLUTION: This device is provided with a power source battery 1, electroluminescence elements 4A, 4B, a boosting driver 3 driving the electroluminescence elements 4A, 4B, and a voltage stabilizer circuit 2 provided between the boosting driver 3 and the power source battery 1. Thus, as the voltage stabilizing circuit 2 is provided between the boosting driver 3 and the power source battery 1, brightness of the electroluminescence elements 4A, 4B can be held almost constant and fully bright independently of a new battery or an old battery. Therefore, accurate information can be informed to a photographer. Further, as output voltage of the boosting driver 3 is not varied depending on a load state, plural electroluminescence elements 4A, 4B can be driven by one boosting driver 43.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electroluminescence display device using electroluminescence (EL).

[0002]

2. Description of the Related Art Conventionally, in driving an EL, a driving power source is directly obtained from a battery as shown in FIG. That is, the EL drive circuit 3 and the battery 1 were directly connected.

[0003]

However, since the battery 1 has an internal resistance, the battery output drops when a relatively large current flows when the motor is driven or the magnet is energized. (Points A, B, and C in FIG. 3). Therefore, there is a problem that the EL display flickers, and the photographing information is not accurately transmitted to the photographer.

Further, there is a problem that the EL display becomes dark when the remaining battery level decreases, particularly when the battery check reaches a power supply voltage level at which the battery cannot be operated. That is, when the difference between the initial voltage of the battery and the battery-warning level voltage is large, there is a drawback that the EL brightness difference becomes large (points D and E in FIG. 2).

The present invention has been made in view of the above problems, and it is an object of the present invention to reduce the luminance change of EL due to the voltage change of the battery.

[0006]

In order to achieve this object, the electroluminescence display of the present invention comprises a power supply battery (1) and an electroluminescence device (4).
A booster driver (3) for driving the electroluminescence element, and a voltage stabilizing circuit (2) provided between the booster driver and the power supply battery.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block connection diagram showing an embodiment of an electroluminescence display device according to the present invention.

In FIG. 1, reference numeral 1 is a battery. As the battery 1, an alkaline dry battery, a lithium battery, a nicad battery, a nickel hydrogen battery, or the like is used. Reference numeral 2 is a series regulator, which drops the voltage input from the battery to a predetermined voltage and supplies it to the EL drive circuit 3. As the series regulator 2, a mini-mold type three-terminal regulator is easy to use. However, it is needless to say that an external power transistor may be attached when power is required to brighten the EL.

The series regulator 2 includes a regulator IC block 20, a PNP transistor 30, and a resistor R.
1 and a resistor R2. The positive electrode of the battery 1 is connected to the emitter of the transistor 30, and the resistor R1 is connected between the emitter and the base of the transistor 30. Further, the battery 1 is a regulator IC block 2
0, the power source of the operational amplifier 23 and the constant current circuit 21.
It is connected to the. The constant current circuit 21 is connected to the reference voltage generation circuit 22, and the output of the reference voltage generation circuit 22 is input to the negative input terminal of the operational amplifier 23. The output of the operational amplifier 23 is connected to one end of the resistor R2, and the other end is connected to the base of the transistor 30 and the resistor R1.
The collector of the transistor 30 is the output of the regulator 2 and is connected to the power supply line of the EL drive circuit 3. Further, in order to feed back the voltage, the collector of the transistor 30 has a resistor 24 in the regulator IC block 20.
, And the other end of the resistor 24 is connected to the resistor 25 and the positive input terminal of the operational amplifier 23.

The chip select terminal (C
E) is connected to the CPU 6. When the chip select terminal (CE) is low level (L), regulator IC
Block 20 operates. That is, the operational amplifier 23 operates, a constant voltage is input to the negative input terminal of the operational amplifier 23, and the stabilized output voltage (divided by the resistors 24 and 25) is input to the positive input terminal.

Immediately before the operation of the operational amplifier 23, the output voltage is 0.
Since it is V, 0V is applied to the plus input terminal.
That is, a higher voltage is applied to the negative input terminal. Therefore, the output of the operational amplifier 23 becomes low level, the base potential of the transistor 30 drops, and the transistor 30 starts to operate. When the transistor 30 operates, feedback is applied so that the output voltage (divided by the resistors 24 and 25) and the reference voltage have the same potential.
That is, when the chip select terminal (CE) of the regulator IC block 20 is at L, the regulator 2 operates and drops the voltage input from the battery to a predetermined voltage, so that E
It is supplied to the L drive circuit 3. On the other hand, when the chip select terminal (CE) is H, the transistor 30 is turned off and E
No power is supplied to the L drive circuit 3.

The EL driver-3 boosts the predetermined voltage supplied from the series regulator 2 to a level at which EL emits light at a predetermined frequency. The EL drive circuit 3 has an E
Self-excited oscillation of LC oscillation due to the capacitance component of L and the inductance component of the step-up transformer, and external excitation by turning on EL by inputting a control signal such as a clock signal from the outside so as to repeat step-up start and step-down stop at a predetermined cycle There are two types of oscillation.

EL elements 4A and 4B are turned on when backlight illumination of the display means (LCD) 11 is required. A DC / DC converter 5 is controlled by a control signal supplied from the CPU 6. When the control signal is L, the DC / DC converter 5 does not start and the CPU 6 is controlled by the internal regulator.
It outputs the energy for driving low current consumption. When the control signal is H, the DC / DC converter 5 is activated and a constant voltage is applied to the CPU 6, the photometry circuit 7, and the distance measurement circuit 8 regardless of the power fluctuation of the battery due to the large current flowing through the motor. , And the shutter control circuit 9. The CPU 6 includes a DC / DC converter 5, an EL drive circuit 3, a photometry circuit 7, a distance measurement circuit 8, a shutter control circuit 9, a film feeding means 10, a display means 11, a lens motor control means 12, and switches Sw1 to Sw1. Sw4
Is connected and controls the entire camera.

The photometric circuit 7 measures the brightness of the object using a well-known SPD, CCD or the like and sends it to the CPU 6. The distance measuring circuit 8 is a phase difference method using a pair of CCDs (passive AF) or various AF methods such as a triangulation method (active AF) that irradiates an object with infrared light and uses the reflected light. The distance to the subject is measured, transmitted to the CPU 6, and the lens motor control means 1 is sent by the control signal from the CPU 6.
2 is controlled to drive the taking lens. A signal for controlling the aperture and shutter speed is input from the CPU 6 to the shutter control circuit 9 based on the information from the photometry circuit 7 and the distance measurement circuit 8, and the aperture control and the shutter control are performed on the basis of the signals to perform film control. Expose.

Reference numeral 10 is a film feeding control means, which is a CPU 6
The film feeding motor is controlled by controlling the feeding motor based on the signal from. Reference numeral 11 denotes a display unit that displays shooting information based on the data from the CPU 6 by using an LED or an LCD so that the user can understand the shooting information. Further, on the back surface of the LCD, an EL element 4 for backlight is arranged. Reference numeral 12 is a lens motor control means, which controls the photographic lens motor.

The switch Sw1 is a main switch,
It is connected to the CPU 6 and activates the DC / DC converter 5 based on the operation of the switch Sw1. When the photographer operates the switches Sw2 and Sw3, the photographing operation starts. The switch Sw2 is a half-push switch of the camera and is connected to the CPU 6. By pressing the switch Sw2 halfway, the brightness of the subject is measured (photometering circuit 7), the focus of the subject is detected, and the focus of the subject is adjusted (distance measuring circuit 8). The switch Sw3 is a release switch of the camera and is connected to the CPU 6. By the release operation of the switch Sw3, the shutter control circuit 9 exposes the subject while the subject is in focus, and the film feeding means 10 feeds one frame. Switch Sw4
Is an EL lighting control switch, which is connected to the CPU 6. Press the switch Sw4 for a certain time C
A lighting signal is output from the PU 6 to the EL drive circuit 3 to light the EL element 4 for a certain period of time.

FIG. 2 is a graph showing the number of images taken on the horizontal axis and the voltage at each point on the vertical axis, showing the battery voltage, the output voltage of the series regulator 2 and the output voltage of the DC / DC converter 5. As shown in FIG. 2, the EL drive circuit voltage is constant at the output voltage of the series regulator 2 regardless of whether the battery is a new battery or an old battery whose battery warning level is very low. FIG.
FIG. 3 is an enlarged view of FIG. 2, which is a voltage waveform when a single film is photographed. When a large current flows through the AF motor, shutter mechanism operation, and feeding motor, that is, at points A, B, and C, the battery voltage drops due to the internal resistance of the battery. However, since the output voltage of the series regulator 2 is constant, the luminance change due to the voltage change does not occur.

FIG. 4 is a flowchart of the first embodiment of the present invention, which will be described with reference to the flowchart.

The program starts when the switch Sw4 is turned on, and the two EL elements 4 are turned on in step S100. That is, the CPU 6 in FIG. 2 outputs a signal to the control terminal of the EL drive circuit 3, whereby the EL drive circuit 3 starts boosting, and the EL element 4 is illuminated by applying a high voltage at a predetermined frequency. . Step S
At 101, the EL display timer is started. In step S102, it is determined whether or not the release switch is pressed, and if it is pressed, the process proceeds to step S103,
If it has not been pressed, the process proceeds to step S108.

In step S103, the distance measuring circuit 8 of FIG.
Based on the information obtained from the lens motor control means 12
To activate the focus on the subject. This time,
As indicated by point A in FIG. 3, the battery voltage drops due to the driving of the AF motor, but the output voltage of the regulator 2 does not change, so that the brightness of the EL element 4 does not change. Step S
In 104, the photometry circuit 7 of FIG. 1 is operated to measure the brightness up to the subject, and the brightness of the subject is measured. In step S105, it is determined whether or not the release switch Sw3 is pressed. If it is pressed, the process proceeds to step S106, and if it is not pressed, the process proceeds to step S109.

In step S106, shutter control is performed to expose the film with an appropriate exposure value that focuses on a desired subject. At this time, as shown at point B in FIG. 3, the battery voltage drops due to energization of the release magnet and the shutter magnet, but the output voltage of the regulator 2 does not change, so the brightness of the EL element 4 does not change. In step S107, the film feeding means 10 is used for the next shooting.
Is operated to feed one frame of film. At this time, as indicated by point C in FIG. 3, the battery voltage drops due to the drive of the feeding motor, but the output voltage of the regulator 2 does not change, so that the brightness of the EL element 4 does not change. In step S109, it is determined whether or not the half-push switch of the switch Sw2 is pressed. If the switch is pressed, the process returns to step S105, and if not, the process proceeds to step S108. In step S108, it is determined whether the EL timer has expired, and if it has not expired, the process returns to step S102. If it is completed, the process proceeds to step S110. Step S11
At 0, the EL element 4 is turned off and the program ends.

During the EL lighting timer, the release switch S
The battery voltage waveform when w1 is pressed is as shown in FIG. The timing of step S103 is point A in FIG. 3, the timing of step S106 is point B in FIG. 3, and the timing of step S107 is point C in FIG. Point A, B
Since the voltage applied to the EL element 4 does not change even at the timings of the point and the point C because it passes through the series regulator 2, the brightness of the EL element 4 does not change.
The shooting information is accurately transmitted to the photographer. Further, as shown in FIG. 2, even when the voltage difference from the initial battery to the battery warning level is large, the light emission brightness of the EL element 4 is changed by bringing the regulator voltage of 2 close to the battery warning level (battery initial and battery warning level). Change to level)
Becomes smaller.

FIG. 5 is a flow chart of the second embodiment of the present invention, which will be described based on the flow chart.

The program is started by turning on the switch Sw4, and two EL elements 4 are turned on in step S100. That is, the CPU 6 of FIG. 2 outputs a signal to the control terminal of the EL drive circuit 3, whereby the EL drive circuit 3 starts boosting, and the EL element 4 is applied with a high voltage at a predetermined frequency and lit. To do. Step S
At 101, the EL display timer is started. In step S102, it is determined whether or not the release switch Sw1 is pressed. If it is pressed, the process proceeds to step S120, and if it is not pressed, the process proceeds to step S108.

In step S120, the EL element 4 is turned off. In the half-pressed state, the photographer normally looks in the viewfinder and rarely sees the external display. Therefore, the EL element 4 is turned off to extend the battery life. Step S1
In 03, the lens motor control means 12 is operated based on the information obtained by the distance measuring circuit 8 in FIG. 1 to focus on the subject. In step S104, the photometric circuit 7 is activated to measure the subject brightness. In step S105, it is determined whether or not the release switch Sw3 is pressed. If it is pressed, the process proceeds to step S106, and if it is not pressed, the process proceeds to step S109.

In step S106, shutter control is performed to expose the film at an appropriate exposure value that focuses on a desired subject. In step S107, the film feeding means 10 is operated to feed one frame of film for the next shooting. In step S121, the process waits until the half-press switch Sw2 turns off, and when the half-press switch Sw2 turns off, the process proceeds to step S122.

In step S109, the half-press switch S
It is determined whether or not w2 is pressed, and if it is pressed, the procedure returns to step S105, and if not, step S
Proceed to 122. In step S122, the EL timer is started again. In step S123, the EL element 4 is turned on so that the next setting can be confirmed quickly. In step S108, it is determined whether or not the EL timer has ended, and if it has not ended, step S10.
Return to 2. If it is completed, the process proceeds to step S110. In step S110, the EL element 4 is turned off and the program ends.

That is, when the half-push switch Sw2 is pressed during the EL lighting timer, the photographer is looking into the viewfinder, so that it is not necessary to actively illuminate the display of the external LCD with the EL element 4, and the display is turned off. It is possible to reduce the current consumption of the battery.

Further, when the voltage difference from the battery initial stage to the battery warning level is large as shown in FIG. 2, the output voltage of the regulator 2 is brought close to the battery warning level, as in the first embodiment, so that the EL element 4 The change in the light emission brightness of (the change between the initial battery and the battery warning level) becomes small.

[0031]

As described above, according to the electroluminescence display of the present invention, since the voltage stabilizing circuit is provided between the step-up driver and the power source battery, the brightness of the EL element can be improved regardless of whether it is a new battery or an old battery. Since almost constant and sufficient brightness can be obtained, information can be accurately transmitted to the photographer.

Further, when the LCD display contents are difficult to see in a dark environment, even if the backlight of the EL element is turned on and the shutter is released, the display illumination does not flicker and the photographed information can be accurately transmitted to the photographer. is there.

Further, since the output voltage of the EL drive circuit does not change depending on the load condition, there is an effect that one EL drive circuit can drive a plurality of EL elements.

[Brief description of drawings]

FIG. 1 is a block connection diagram showing an embodiment of an electroluminescence display according to the present invention.

FIG. 2 is a characteristic diagram showing an embodiment of an electroluminescence display device according to the present invention.

FIG. 3 is a characteristic diagram showing an embodiment of an electroluminescence display device according to the present invention.

FIG. 4 is a flowchart showing a first embodiment of the electroluminescence display device according to the present invention.

FIG. 5 is a flowchart showing a second embodiment of the electroluminescence display device according to the present invention.

FIG. 6 is a block connection diagram showing an example of a conventional electroluminescence display device.

[Explanation of symbols]

 1 Battery 2 Series Regulator 3 EL Driving Circuit 4 EL Element 4A EL Element 4B EL Element 5 DC / DC Converter 6 CPU 7 Photometric Circuit 8 Distance Measuring Circuit 9 Shutter Control Circuit 10 Film Feeding Means 11 Display Means 12 Lens Motor Control Means 20 Regulator IC block 21 Constant current circuit 22 Reference voltage generation circuit 23 Operational amplifier 24 Resistor 25 Resistor 30 PNP transistor Sw1 switch Sw2 switch Sw3 switch Sw4 switch

Front page continuation (72) Inventor Takeharu Kato 3 2-3 Marunouchi, Chiyoda-ku, Tokyo Inside Nikon Corporation

Claims (3)

[Claims] 1. An electroluminescence display comprising: a power supply battery; an electroluminescence element; a boost driver for driving the electroluminescence element; and a voltage stabilizing circuit provided between the boost driver and the power supply battery. 2. The electroluminescence display device according to claim 1, wherein a plurality of electroluminescence elements are turned on by one boost driver. 3. The electroluminescence display device according to claim 1, wherein the output voltage of the voltage stabilizing circuit is set to a predetermined level or lower.