JPS6017316A - Compensating circuit of temperature - Google Patents

Abstract

PURPOSE:To drive the constant current of a load over the whole temperature by providing a regulator circuit for an IC power supply with an element for uniforming variables changed by respective temperature characteristics of the regulator circuit and a load side circuit. CONSTITUTION:Control signal output voltage applied from a controlling integrated circuit (CMOS) 8 is approximately equal to the power supply voltage, the emitter current of a transistor (TR) 10 is constant current and the constant current flows into the load 17 connected to a TR 16. If environmental temperature is changed, the emitter current of the TR 10 is shown by the formula when the changed variable of the power supply VDD due to the temperature change of a diode 4 is DELTAVDD and the changed variable of voltage between the base and emitter of the TR 10 is DELTAVBEIO. Since the element having change similar to that of the voltage between the base and emitter of the TR 10 due to temperature, the DELTAVDD is made equal to the DELTAVBEIO and constant current is made to flow into the load 17.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature compensation circuit that drives a load at constant current or constant voltage.

In recent years, with advances in integrated circuit technology, integrated circuits, particularly microcomputers, have come into use, and sequence control of devices has become easier.

C-MOS type ICs are increasing rapidly due to their low power consumption, but the lack of power in the drive system is compensated for by using large capacity batteries or increasing the number of batteries.

In such a case, in order to reduce the brown voltage to a low voltage for use as an IC power source, -1:fc is generally provided with a regulator circuit in order to prevent the influence of drive system noise.

However, if voltage is simply supplied to the IC via the regulator circuit, the lc'-pressure will be supplied to the IC depending on the temperature, and the voltage output from the IC will also depend on the temperature. A load-side circuit is required to receive this output and drive the load, and since the load-side circuit also has temperature dependence, the output of the load-side circuit cannot always be kept constant.

Furthermore, even if the regulator circuit is temperature-compensated and a constant voltage is supplied to the IC, the output of the load-side circuit cannot be made constant because the load-side circuit has temperature dependence.

In this way, not only when temperature compensation is not applied to the regulator circuit, but even when temperature compensation is applied and a constant voltage is supplied to the IC, the load side circuit has temperature dependence, so it is difficult to drive the load over the entire temperature. However, it is impossible to use a constant current or constant voltage, and this results in subtle differences for products that require precision.

For example, if the load is an electromagnetically driven shutter for a camera that consists of a coil and a magnet, the driving force of the shutter is determined by the product of the number of turns of the coil and the current flowing through the coil. This causes a change in the shutter curtain speed.

The absorption force of the brake, which is always used to rapidly decelerate near the shutter completion position, must be kept constant against changes in the shutter driving force, so if the shutter curtain speed changes due to temperature changes. It becomes very difficult to make a shutter brake.

Furthermore, temperature changes for the electromagnetic shutter are not only due to weather conditions, but also due to uncertain factors such as heat generated by energizing the coil and other heat sources inside the camera.
It cannot be said that the temperatures of the front curtain coil and the rear curtain coil change in a balanced manner.

For the above reasons, such a shutter is more likely to have poor accuracy than a shutter with a normal mechanical drive means, and is also more likely to have uneven cutting and uneven exposure. Also, when adjusting the shutter curtain speed or the time from the start of the first curtain to the start of the second curtain, the adjusted value cannot be guaranteed unless the surrounding and internal temperatures of the camera are kept constant, and readjustment is required. The temperature setting must be considered based on the conditions under which this occurs, and the usual method of estimating the cause of poor shutter accuracy from fluctuations in shutter speed becomes impossible.

In terms of the mechanism of the shutter, considering the increase in shutter curtain speed at low temperatures, it is necessary to ensure strength or durability at the highest curtain speed, and it is necessary to increase the strength unnecessarily. It disappears.

In addition, even if the shutter is not directly driven by an electromagnetic drive means, the drive source for the shutter may be mechanical, such as the stored force of a spring, and the activation means may be released by electromagnetic means such as a suction type magnet. Even in the case where temperature changes cause changes in the current flowing through the coil,
This changes the time from energization to de-energization, resulting in fluctuations in operating time.

The present invention has been made in view of the above-mentioned circumstances, and it supplies a high voltage as a power supply voltage to a control integrated circuit through a regulator circuit, and calculates the change due to the temperature characteristics of the load-side circuit operated by the output of the integrated circuit and the above-mentioned. The present invention provides a temperature compensation circuit that enables constant current or constant voltage drive of a load over the entire temperature range by providing the above regulator circuit with an element that matches changes due to temperature characteristics of the regulator circuit.

An embodiment of the present invention will be described below with reference to FIG.

Figure 1 shows a constant current drive circuit, where 1 is a power supply battery;
2 is a resistor, 6 is a Zener diode, and 4 is a diode used for temperature compensation. Diode 6.4 creates a reference voltage for the regulator. 5
is a capacitor for stabilizing the power supply, 6 is an operational amplifier, and 7 is a transistor, and these resistors 2. Diode 3, 4
A regulator circuit is formed by a capacitor 5z, an operational amplifier 6, and a transistor 7.

8 is a control integrated circuit, particularly a C-MOS type.

10 is a transistor in a load side circuit that receives a control signal from the integrated circuit 8 to drive a load; 9, 11 is a resistor, 12 is an adjustment resistor, 16 is an operational amplifier, 14.15 is a resistor, and 16 is a transistor. Yes, forms a constant current drive circuit. 17 is a load such as a coil of an electromagnetic drive shack, for example.

The temperature compensation diode 4 is connected to the transistor 1.
An element is used that has a change equivalent to the change in the base-emitter voltage of zero depending on the temperature coefficient.

Next, the operation of the above configuration will be explained. transistor 7
The voltage on the emitter side of is equal to the voltage on the + side of the operational amplifier 6. This voltage is supplied to a control integrated circuit (C-MOS) 8. A control signal is output from the Out terminal of the integrated circuit 8, and its output voltage is almost equal to the power supply voltage in the case of C-MOS. Since the emitter current of the transistor 10 is constant, the collector voltage of the transistor 10 is always a constant voltage. The operational amplifier 1'5 operates so that the same potential difference commensurate with this potential difference is generated across the resistor 15. Therefore, the emitter current of the transistor 16 is constant, and a constant current flows through the load 17, for example, a coil, connected to the collector side of the transistor 16.

Now, considering the case where the environmental temperature changes, the IC power supply V
DD changes by the temperature coefficient of the diode 4. Let this amount of change be ΔVDD. On the other hand, the base-emitter voltage of transistor 10 also changes by the temperature coefficient. If this amount of change is ΔVBE10, the emitter current of the transistor 10 will be.

However, the temperature compensation diode 4 is the transistor 10.
ΔVOO and ΔVBE10 are equal because a device is used that has a change equivalent to the change in 0 base-emitter voltage with temperature. Therefore, (1) E-silicon is established, and the same current value as described above flows through the load 17.

In this way, the load 17 can be driven with a constant current over temperature.

Next, another embodiment of the present invention will be described with reference to FIG. 2, in which the same parts as in FIG. 1 are denoted by the same reference numerals, and detailed explanation thereof will be omitted.

25 is an operational amplifier, 24 is a resistor, and 25 is a transistor, forming a constant voltage drive circuit. 26 is a load such as a coil of an electromagnetic shutter.

The temperature compensation diode 4 is connected to the transistor 1.
An element is used that has a change equivalent to the change in the base-emitter voltage of zero depending on the temperature coefficient.

Similarly to the embodiment shown in FIG. 1, the emitter current of the transistor 10 is a constant current, and therefore the collector voltage of the transistor 10 is always a constant voltage. The operational amplifier 26 operates so that the same potential difference commensurate with this potential difference is generated across the load 27.

Now, considering the case where the environmental temperature changes, the IC power supply V
DD changes by the temperature coefficient of the diode 4. Let this amount of change be ΔVDD. On the other hand, the base-emitter voltage of the transistor 10 also changes by the temperature coefficient. If this amount of change is ΔVBE10, the emitter current of the transistor 10 will be.

However, the temperature compensation diode 4 is the transistor 10.
1ΔvDD and ΔVBE10 are equal because an element whose base-emitter voltage changes with temperature is the same as that of 1ΔvDD and ΔVBE10. Therefore, IE:IQ, and a constant voltage similar to that described above is generated across the load 26.

In this way, load 26 can be driven at a constant voltage over temperature.

According to each of the above embodiments, the temperature compensation diode 4 is provided with an element whose temperature characteristics are equivalent to the temperature characteristics of the load side circuit. Alternatively, a resistor may be connected to the transistor 10.

As detailed above, according to the present invention, constant power can be supplied to the load over the entire temperature, and in particular, in the electromagnetic drive means composed of a coil and a magnet,
Even if the resistance value of the coil changes due to temperature changes, if the constant current drive circuit according to the present invention is used, the current flowing through the coil will always be constant, so the electromagnetic drive means will generate a constant driving force and ensure stable operation. A highly accurate electromagnetic drive means can be obtained.

Also, by using a constant voltage drive circuit, highly accurate constant voltage drive can be obtained.

Although a coil is used as the load in the embodiment of the present invention, it goes without saying that high accuracy can be obtained by using other electric elements such as a pseudo load resistor for battery checking.

[Brief explanation of the drawing]

FIG. 1 is a constant current drive circuit diagram showing one embodiment of the present invention, and FIG. 2 is a constant voltage drive circuit diagram showing another embodiment of the present invention. 4...Temperature compensation diode 8...Control integrated circuit 10...Load side drive transistor 15.25.
11+1...Operational amplifier 17, 26...Load

Claims (1)

[Claims] A high voltage is supplied as the power supply voltage of the control integrated circuit through the regulator circuit, and the variation due to the temperature characteristics of the load-side circuit operated by the output of the integrated circuit is matched with the variation due to the temperature characteristics of the regulator circuit. A temperature compensation circuit characterized in that the above-mentioned regulator circuit is provided with an element.