JPH0320089B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lamp voltage generator that generates a lamp voltage for outputting a lamp voltage signal from a computer or sequencer that controls plant processes to the plant side.

A conventional device of this type is shown in FIG. In the figure, TR1 is a transistor, R1
is a resistor, C1 is a capacitor, E _EB , E _CB is a power supply, S
1 is a switch for starting lamp voltage generation, and _Vc is a lamp voltage generated across the capacitor C1.

Next, the operation will be explained. Since the base of the transistor TR1 shown in FIG. 1 is grounded, the collector current of the transistor TR1 is kept at an almost constant value (current amplification factor x emitter current) regardless of the load value. The current amplification factor of transistor TR1 is α
When switch S1 is opened at time t=0, the charging current value of capacitor C1 is
Since it is the collector current value of TR1, it is αE _EB /R.

Next, the voltage generated across capacitor C1 is
It is expressed by the formula V _c = (1/C1)∫ _p ^t idt, where i is the charging current of capacitor C1, and t is the charging current of switch S
This is the elapsed time after opening 1. In this equation, if the charging current i is a constant value I regardless of time, then
V _c = (1/C1), and V _c changes in proportion to time.

In other words, in Fig. 1, the charging current value of capacitor C1 is constant at αE _EB /R, so capacitor C
The voltage V _c generated across 1 is V _c = α (E _EB /
C1R1) t, which has a waveform whose magnitude increases from 0 in proportion to time after time t = 0.
The ramp voltage has a slope of α(E _EB /C1R1).

FIG. 2 shows a voltage waveform generated across the capacitor C1 in FIG. 1, with the horizontal axis representing time and the vertical axis representing the generated voltage.

After the switch S1 is opened at time t=0, the voltage generated across the capacitor C1 rises with a slope α (E _EB /C1R1), and the lamp voltage and the power supply E _CB
FIG. 2 shows a state in which the generation of the lamp voltage ends when the voltages become approximately equal.

Since the conventional lamp voltage generator is configured as described above, in order to change the slope of the lamp voltage, it is necessary to vary or change at least one of the power source E _EB , the capacitor C1, and the resistor R1. Setting the final voltage value also depends on the power supply _ECB , making it cumbersome to change the lamp voltage waveform. Further, since the current amplification factor α of the transistor TR1 changes little by little depending on the value of the collector current, it is difficult to obtain an accurate lamp voltage waveform.

This invention was made to eliminate the drawbacks of the conventional ones as described above, and it digitally processes lamp voltage slope data set by a digital switch over time, and converts the processed data and DA conversion. By converting it into an analog value with a device and outputting the lamp voltage amplified by an amplifier, settings such as the slope of the lamp voltage can be performed more easily than with a digital switch, and accuracy can be increased by using digital arithmetic processing and a DA converter. The object of the present invention is to provide a lamp voltage generator that can generate a lamp voltage waveform with a good quality.

Embodiments of the invention will be described below with reference to the drawings. FIG. 3 is a block diagram showing an embodiment of the present invention, where SD is the first digital switch for numerically setting the final value of the lamp output voltage, and ST is the first digital switch for numerically setting the final value of the lamp output voltage.
is the second digital switch to numerically set the time until the lamp output voltage reaches the final value, S1 is the switch to start generating lamp voltage, CP1 is the switch that reads and calculates the set values of switch SD and ST. DA1 is a DA converter that converts the digital data output from the arithmetic processing unit CP1 into an analog signal and sends it to the next stage.
A1 is an amplifier that amplifies the analog signal output from the DA converter DA1 and outputs it as a ramp voltage.
V _c is the lamp voltage output by amplifier A1,
RP and RT are pull-up resistors for switches SD, ST, and S1.

It is assumed that the arithmetic processing unit CP1 has a timer or equivalent means, and the data update time interval obtained from this timer is one unit time of the arrival time STn. The data setting value of the data setting switch is SDn for switch SD and STn for switch ST.
The operation will be explained below assuming that the digital data of is set. When the switch S1 is closed, the arithmetic processing unit CP1 outputs the switches SD and ST.
Read the data SDn and STn set to , and perform arithmetic processing on the data as shown in the flowchart shown in Figure 4. By monitoring the timer, the lamp voltage that is output to the DA converter DA1 at fixed intervals is as close as possible to the lamp voltage that should be output at that time. Sends digital data and simulates lamp voltage. This output state is shown in Figure 5, which shows two examples of the output waveform of the output V _c of the amplifier A1, a ramp waveform of I1 and I2, and a ramp simulating the waveforms I1 and I2, respectively. These are the waveforms E1 and E2 of the output V _c of the voltage generator.

Data sent from the arithmetic processing unit CP1 to the DA converter DA1 is subjected to data arithmetic processing in two cases as follows.

One is to compare the final arrival value SDn and the arrival time STn, and if the final arrival value SDn is equal to or larger than the arrival time STn, the following calculation processes (1) to (7) are repeatedly executed. However, since the lamp voltage start switch S1 is closed, the arithmetic processing unit CP1 outputs the data buffer DV _X data buffer DV _Y and
It is assumed that the data sent to the DA converter is initialized to 0.

(1) Divide the final arrival value SDn by the arrival time STn, take the resulting quotient as DX1, the remainder as DE1, add the values of the data buffer DV _Y and the remainder DE1, and create a new data buffer DV _Y. be the value of

(2) Compare the value of the data buffer DV _Y and the value of the arrival time STn, and if the values of the data buffer DV _Y are equal or larger, add 1 to the quotient DV1, and calculate the arrival time STn from the data buffer DV _Y. Subtract the value and use this as the new data buffer DV _Y value.

(3) Add the value of quotient DX1 and data buffer DV _X and use this as the new value of data buffer DV _X.

(4) The timer monitors the data buffer when it is time to send data to the DA converter DA1.
Sends DV _X data to DA converter DA1.

(5) Reduce the value of quotient DX1 from the final achieved value SDn and use this value as the new final achieved value SDn.

(6) Subtract 1 from the arrival time STn and use this value as the new arrival time STn.

(7) When the value of arrival time STn becomes 0, the lamp voltage output is completed, so the calculation process ends; if it is not 0, the calculation process is repeated in order from (1).

Through the above processing, the lamp voltage waveform shown by E1 in FIG. 5 is output.

The other is the arrival time STn than the final arrival value SDn.
This is also the case when the data buffer is larger.
The arithmetic processing from (1) to (9) will be demonstrated assuming that the initial values of the DV _X data buffer DV _Y and the data sent to the DA converter are 0.

(1) Add 1 to the final value SDn as data.
DV ₂ .

(2) Divide the arrival time STn by the data DV ₂ and use the resulting quotient as the quotient DX2 with the remainder as DE ₂ .

(3) Add the remainder DE ₂ and the value of the data buffer DV _X , and use this as the new value of the data buffer DV _X.

(4) Compare the value of data buffer _{DV X} and the value of data _{DV 2} , and if the value of data buffer _DV subtract the value,
The result is set as the new data buffer DV _X value.

(5) Monitor the timer and when it is time to send data to DA converter DA1, data buffer DV _Y
data is sent to the DA converter DA1.

(6) Subtract 1 from the value of quotient DX2, and also subtract 1 from the value of arrival time STn.

(7) When the arrival time STn becomes 0, the output of the lamp voltage is completed, so the calculation process ends.

(8) When the value of quotient DX2 becomes 0, increase the value of data buffer DV _Y by 1, and increase the value of final value SDn by 1.
decrease. After that, the arithmetic processing from (1) is executed in order from (1).

(9) Execute the arithmetic processing from (5) in order.

Through the above processing, the lamp voltage waveform shown by E2 in FIG. 5 is output.

The lamp voltage generated through the above calculation process is the final value set by the switches SD and ST.
SDn, slope determined by arrival time STn
This is the ramp voltage of SDn/STn.

By performing arithmetic processing in this way, the DA converter
The output error of the data sent to DA1 with respect to the ideal ramp waveform is suppressed to ±1LSB or less when updating data. Especially the arrival time from the final arrival value SDn
If STn is larger, the error is less than ±1 LSB at all lamp output times, so if the resolution and accuracy of the DA converter DA1 are taken into account, a highly accurate lamp voltage can be generated.

In the above embodiment, the case where the lamp voltage increases has been described, but it is also possible to generate a lamp voltage having a negative slope by partially changing the data calculation process. Further, the lamp voltage need not be generated from OV, but it is also possible to start generating the lamp voltage from a certain voltage. Also, it does not need to be a switch for setting the final value and arrival time of the switch to start generating lamp voltage; it can be any switch that can set data, so it can be used instead of a switch on the CPU's data control bus. May be connected.

If a waveform shaping circuit such as a low pass filter is added to the output of the above embodiment, an even smoother lamp output waveform can be obtained.

Although the case where the lamp output is a voltage has been described, the output may be a current. In this case, the present invention becomes a current generating device in which the current value changes like a ramp function.

As described above, according to the present invention, the lamp voltage waveform is processed as digital data, and the processed data is converted into an analog quantity by the DA converter to simulate the lamp voltage, so the slope of the lamp voltage is controlled by the digital switch. It is easy to set, and the accuracy of the lamp voltage waveform can be achieved by appropriately setting the accuracy and resolution of the DA converter and the update time interval of data sent to the DA converter.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram showing a conventional device, FIG. 2 is a waveform diagram showing the output state of the device in FIG. 1, FIG. 3 is a block diagram showing an embodiment of the present invention, and FIG. a flowchart showing the operation of the device in FIG. 3;
FIG. 5 is a waveform diagram showing the output of the device in FIG. 3. In the figure, SD and ST are the first and second digital switches for data setting, CP
1 is an arithmetic processing unit, DA1 is a DA converter, A1 is an amplifier, V _c is an output, S1 is a switch for starting lamp voltage generation, and RP and RT are pull-up resistors of each switch. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1 First digital switch for numerically setting the final voltage value in order to set the slope of the lamp voltage from the initialized output voltage value to the final voltage value and the time it takes to reach the final voltage value a second digital switch for numerically setting the slope; and a lamp voltage corresponding to the slope by reading the data of the first and second digital switches and calculating the lamp voltage corresponding to the slope at each preset data update time interval. A calculation processing unit that outputs the simulated lamp output value closest to the value as digital data, and converts the output digital data to an analog quantity.
A lamp voltage generator comprising: a DA converter; an amplifier that amplifies the output of the DA converter and outputs a lamp voltage; and a switch that notifies an arithmetic processing unit of the start of lamp voltage output.