JPS6154512A - Temperature controller - Google Patents

Abstract

PURPOSE:To attain the control of temperatures with high accuracy by providing plural heaters and controlling indepenently the electric power which is supplied to each heater in response to the difference between the temperature of a body to be controlled and the set temperature to be maintained. CONSTITUTION:A set temperature input device 13 and a memory 14 are connected to a central controller 12. The memory 14 stores previously the difference between a set temperature T0 and the set temperature T0 which should be maintained for developing solution and the temperature T detected by a temperature detector 2 respectively together with the relation of electric power among heaters H1-Hn. The temperature of the developing solution, i.e., a body to be controlled is detected and supplied to the controller 12. The controller 12 calculates the difference between temperatues T and T0. Then the electric power value to be supplied to each heater is obtained according to the relation between the difference of temperatures stored in the memory 14 and the electric power to be supplied to the ach heater. Then the prescribed electric power is supplied to heaters H1-Hn respectively via a drive circuit 15.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a temperature control device, and particularly to a temperature control device that can control the temperature of a controlled object with high precision.

(Prior Art) Strict temperature control is required in devices such as constant temperature baths and photographic developing tanks that must maintain a constant temperature of -1 at all times. To perform temperature control, the temperature of the controlled object is detected and thermal energy is supplied from the heater to maintain the temperature within a constant range.The heater, which is the heating source, has a predetermined heat capacity. As a result, there is a delay in the response time for supplying a predetermined amount of heat to the surrounding area, and there is a problem in that it is difficult to maintain the temperature of the controlled object within a narrow temperature range.

There is an on-off type temperature control device as a temperature control device that has been widely put into practical use. This on-off type temperature control device sets an upper limit temperature T and a lower limit temperature T2 around the set temperature to be maintained, turns off the heater when the controlled object reaches the upper limit temperature T, and returns the temperature to the lower limit temperature T2. When the temperature is reached, the heater is turned on and a power of 100x is supplied to the heater to maintain the controlled object within a predetermined temperature range.

This on-off type temperature control device has the advantage of having a relatively simple control circuit configuration, but the amount of overshoot is large due to the time delay in the rise and fall of the heater. There is a drawback that the actual temperature fluctuation range is wider than the set temperature range.

(Problems to be Solved by the Invention) Figure 1A shows the actual temperature of the controlled object when controlled using a conventional on-off type temperature control device, and Figure 1B shows the temperature supplied to the heater at this time. represents the electric power generated. 1st
As can be understood from the figure, if the heater is turned off when the upper limit temperature T is reached, residual heat from the heater will be transferred to the surroundings even after the heater is turned off, causing the actual temperature to exceed the upper limit temperature T. If the heater is turned on while the lower limit temperature T2 is reached, there will be a delay in the startup response of the heater, and the actual temperature will become lower than the lower limit temperature T2. For this reason, even if a high-precision temperature detector is used and the temperature difference between the upper limit temperature T and lower limit temperature T2 is set as small as possible, overshoot at rise and fall causes the controlled object to be kept within a narrow temperature range. There are drawbacks that cannot be maintained. Particularly when using a large-capacity heater, there is a drawback that the amount of overshoot is large and it is difficult to maintain the temperature within a narrow temperature range.

Therefore, in equipment that requires highly accurate temperature control, such as photographic developing tanks, on-off type temperature control devices have limits in terms of accuracy, and there is a strong demand for the development of temperature control devices that can control with even higher precision. There is.

(Means for Solving the Problems) The present invention provides a temperature control device that can control temperature with high precision, and includes a temperature detector that detects the temperature of a controlled object and a setting that inputs the temperature to be maintained. It is characterized by comprising a temperature input means and a plurality of heaters, and controlling the electric horns supplied to the plurality of heaters individually according to the temperature difference between the detected temperature detected by the temperature detector and a set temperature. It is something to do.

(Function) The present invention uses a plurality of heaters to individually control the power supplied to each heater according to the temperature difference between the temperature of the controlled object and the set temperature to be maintained. Highly accurate temperature control is performed by minimizing the range of temperature fluctuations. In other words, it is possible to warm up the temperature gradient near the set temperature by controlling each of multiple heaters on and off, controlling the power supplied to each heater, or combining these controls. , Therefore, overshoot and undershoot can be suppressed as much as possible.

(Example) FIG. 2 is a diagrammatic sectional view showing the structure of an example of a photographic developing tank using the temperature control device according to the present invention. tank 1
n heaters H+, Hz...Hl and a temperature detector 2 are provided inside the tank 1, and a circulation path 4 and a pump 5 for circulating the developer 3 are provided outside the tank 1, and a pump 5 for circulating the developer 3. A cooling water inlet 6 and a discharge lower are provided for forced cooling.

The cooling water is supplied and discharged only when the developer 3 becomes abnormally high in temperature. The developer 3 is circulated in the tank 1 by the pump 5, and when its temperature is not detected by the temperature detector 2, it is uniformly heated by the heater I (+, Hz...H, % and kept at a constant temperature at all times. Ru.

FIG. 3 is a block diagram showing the configuration of an example of a temperature control device according to the present invention. Temperature detector 2 installed inside tank 1
is connected to a sensor amplification device 10 to amplify the detected temperature signal of the developer 3 and manually input it to the central control device (C, P, υ,) 12 via the A/D converter 11.

A set temperature input device 13 and a memory 14 are connected to this central control device 12, and a set temperature T(
The relationship between the temperature difference between the temperature T detected by the temperature detector 1 and the temperature detector 2 and the set temperature T0 and the power to be supplied to each heater H+, Hz...Hl is input in advance into the memory 14 (.
A drive circuit 15 for supplying predetermined power to each of the heaters H1, H2, . , Hz...Connect H7. This drive circuit 15 drives each heater in response to a command from the central controller 12 so as to supply a predetermined power to each heater independently. When the temperature of the developer 3, which is the object to be controlled, is detected and input to the central controller 12, the central controller 12 calculates the temperature difference between the detected temperature T and the set temperature T0, and calculates the temperature difference stored in the memory 14 and each temperature difference. Based on the relationship with the power to be supplied to the heaters, the value of the power to be supplied to each heater H1, H2, .

The drive circuit 15 independently supplies predetermined power to each heater H, , H, . . . , based on a command from the central controller 12 . As a heater driving method in the drive circuit 15, the following method can be considered (1) Each heater H1°H2...H according to the 1Mt degree difference ('r-To)
control the total power supply by turning the power on and off individually. This heater driving method is illustrated in Table 1.

The duty tl control is performed by changing the interval, and the power supplied to each heater is individually changed to control the total power supply.

(3) Use (1) and (2) above together. That is, some of the heaters are controlled on and off, and the power supplied to the remaining heaters is freely changed to control the total power supply.

Next, the amount of temperature change when temperature is controlled using the temperature control device according to the present invention will be explained.

FIG. 4A schematically shows the temperature change with respect to time, and FIG. 8 schematically shows the change in the total power supply amount.

In this example, there are two on the high temperature side and low temperature side of the set temperature T0.
Temperature difference between stages - ”rr ”2r ”2+ tl
It is assumed that the heater drive is performed as shown in Table 2.

Table 2 As can be seen from Figure 4, when a power of 100χ is supplied to the rated value, the temperature of the controlled object suddenly increases (4.<t<t, control temperature range When the temperature reaches the limit temperature To of the high temperature side of the control temperature, the supply power gradually decreases and the temperature gradually increases.
When +t2 is reached, the amount of overshoot becomes extremely small because the thermal energy possessed by the heater is small. At the moment when the temperature exceeds 70+t and all the heaters are turned off, there is a sudden temperature drop, but since power is supplied immediately after that, the temperature drops gradually as the temperature drops. Then, the lowest limit value To of the control temperature range
When -tI is reached, a large amount of thermal energy is being supplied, so the transition from falling to rising occurs in a short time, and the amount of overshoot becomes extremely small. Furthermore, the temperature changes slowly, and the range of variation is extremely small compared to on-off type control.

Therefore, by dividing the control range into narrow sections and configuring to supply appropriate power to each heater within each temperature category, it is possible to extremely reduce the amount of temperature change of the controlled object within the control temperature range. Highly accurate temperature control can be performed.

Next, the setting conditions when specifically used as a temperature control device for a photographic developing tank, which particularly requires highly accurate temperature control, will be explained.

FIG. 5 is a perspective view showing the arrangement position of the heater.

In this example, three heaters H+, Hz, and H3 with a rating of 750- are installed at equal positions in the developing tank as shown in the figure to uniformly heat the circulating developer.

FIG. 6 is a block diagram showing the configuration of the control circuit. A temperature detector (not shown) provided in the developing tank is connected to the central control device 20, and a set temperature input device 21 and a memory 22 are also connected to the central control device 20 to calculate the relationship between the temperature difference and the supplied power shown in Table 3. Enter it. Further, an I10 port 23 is connected to the central control unit 20 via a data bus line,
0 boat 23 has three buffers 24, 25 and 26 connected to three solitary relays 27, 28 and 29.
Connect. Connect the ■terminals on the input side of each solid state relay 27 to 29 to the driving power supply of 5■, respectively.
Each e terminal is connected to the output terminal of each buffer 24-26. Further, one terminal on the output side of each of the solid state relays 27 to 29 is connected to one terminal of a 100 V AC power source, which is a power source for the heater, and the other terminals are connected to the heaters H, , H.

and H3, and the other ends of the heaters H3 to H3 are respectively connected to the other terminal of the AC 100V power supply.

The power supply to each heater H1 to H3 is controlled by controlling the opening/closing time of each solid relay 27 to 29 per unit time.

Table 3 Table 3 shows the relationship between the developer temperature in the developer tank detected by the temperature detector and the power supplied to the heater.

In this example, the temperature to be maintained for the developer is set at 32.80'C, and six temperature ranges are set at intervals of 0.02°C on the high and low temperatures, respectively, as shown in Table 3. Power is supplied to heaters II, H and 11.

As a result of setting the conditions and controlling the temperature in this way, 32.
80 Can be controlled within a range of ±0.03.

On the other hand, when on-off type temperature control is performed under the same conditions, 32.8
The temperature was controlled within a temperature range of 0±0.30.

Therefore, if the temperature control device according to the present invention is used, it is possible to control the temperature in a temperature range that is 1/10 that of the conventional on-off type temperature control device.

In this way, by configuring a plurality of heaters to supply appropriate power to each individual heater, the transmission efficiency from the heaters increases and temperature control can be performed with high precision.

(Effects of the Invention) As explained above, according to the present invention, it is possible to extremely reduce the amount of overshoot at the rise and fall of the heater, and since the temperature of the controlled object changes extremely gradually, the temperature range is small. The temperature can be controlled with high precision over the entire range.

In addition, if the appropriate amount of thermal energy necessary to maintain the set temperature is determined based on the temporal change in temperature, and the relationship between the temperature difference and the supplied power is determined based on the electric power comparable to this amount of thermal energy, , more accurate temperature control can be performed.

[Brief explanation of drawings]

Figure 1A is a graph showing the temperature change of the controlled object when temperature control is performed using an on-off type temperature control device, Figure 1B is a graph showing the change in heater power supply, and Figure 2 is a graph showing the temperature control of the controlled object using an on-off type temperature control device. A diagrammatic sectional view showing the configuration of an example of a photographic developing tank using the temperature control device according to the invention, FIG. 3 is a block diagram showing the configuration of an example of the temperature control device according to the invention, and FIG. 4A is the invention Figure 5 is a graph schematically showing temperature changes when temperature is controlled using a temperature control device according to the present invention. Figure B is a graph showing changes in supplied power. FIG. 6 is a perspective view showing the arrangement of the heater when specifically used as a regulator; FIG. 6 is a block diagram showing a specific example of the control circuit. 1...Developing tank 2...Temperature detector 3...
Developer 4...Circulation path 5...Pump
6... Cooling water supply lower... Outlet H
r, Hz...lHI'l...Heater 10...Sensor amplifier 11...A/D converter 12.20...
Central controller 13.21...Set temperature manual device 14.22...Memory 23...I10 boats 24, 25, 26...Buffer 27.28.29...Solid state relay Fig. 2L (Inkstone image omitted tank) Figure 1 Time - Figure 3

Claims (1)

[Claims] 1. A temperature detector that detects the temperature of a controlled object, a set temperature input means that inputs the temperature to be maintained, and a plurality of heaters, and a temperature detector that detects the temperature detected by the temperature detector and a set temperature. A temperature control device that controls power supplied to each of the plurality of heaters according to a temperature difference.