JPH0245904Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to an automatic brightness adjustment circuit for a CRT that can automatically adjust the brightness of a CRT in a device that uses a combination of a CRT and a light pen.

(Prior technology) Combining a CRT display and a light pen, CRT
There is a system that inputs various information by interacting with a CRT using a light pen according to the sequence displayed on the screen. In such a system, the operating procedure when using a combination of a CRT and a light pen can be divided into the following three steps.

A process in which neither a CRT nor a light pen is used A process in which only CRT display is performed and no light pen is used A process in which both a CRT and a light pen are used
CRT display brightness (hereinafter simply referred to as brightness) varies. Therefore, when operating such a system, it is desirable that the brightness be automatically set to the optimum sensitivity in each step. However, currently, the initially set brightness is used in common for each process, so the brightness is ultimately set according to the third process (the process using a CRT and light pen) that requires maximum brightness. Ru. According to this conventional method, although the CRT is not used in the first process and therefore does not require any brightness, the maximum brightness is given to the CRT, so CRT burn-in does not occur. ,
Lifespan will also be shortened.

Also, in the second process, as in the first process, burn-in occurs because the brightness is set higher than necessary. In addition, in this case, unnecessary strain will be placed on the eyes of the operator observing the CRT display. In order to deal with reductions in brightness and changes in the sensitivity of the light pen body due to burn-in, the operator must reset the brightness each time by operating the adjustment knob, keyboard, etc. be. The problems of the conventional system described above are listed below.

(1) Brightness is always set to maximum brightness, so
Burn-in on the CRT display surface is more likely to occur,
Life expectancy will be shortened.

(2) Images are always displayed at maximum brightness, which puts excessive strain on the eyes of the operator.

(3) The operator must perform adjustment operations each time to respond to a decrease in CRT brightness or a change in light pen sensitivity.

(Purpose of the invention) The present invention was made in view of the above points, and its purpose is to realize an automatic brightness adjustment circuit for CRTs that automatically sets the optimum brightness in each of the above processes. It's about doing.

(Structure of the invention) The present invention, which achieves the above object, is a circuit used in a device that uses a CRT in combination with a light pen. In the case where the operation procedure can be divided into three steps (using both the CRT and the light pen), there is a detection circuit that detects each of the above steps, and a luminance information that generates luminance information according to the output of the detection circuit. The luminance information generating circuit is characterized in that it is provided with an information generating circuit, and is configured such that the output of the luminance information generating circuit can be varied according to the three processes described above.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an electrical configuration diagram showing an embodiment of the present invention. In the figure, 1 is a latch circuit that latches and stores the light pen on signal (hereinafter abbreviated as LO) generated when operating a light pen (not shown) using a separately provided VT signal, and 2 is a VT signal. 3 is an up-down signal generating circuit that generates a signal indicating whether the up-down counter _U1 is counting up or down; 4 is a pulse generating circuit 2 This pulse is sent to the up/down counter.
A count control circuit controls whether or not to send the VT signal to _U1 as a counter clock, 5 is an AND gate that receives the output of the count control circuit 4 at one input, and 6 loads the VT signal to the up-down counter _U1 . This is a switching circuit that switches between using the signal as a clock signal and as a counter clock.
Switching is performed by switch SW ₁ provided at the input section. 7 is an operation control circuit that receives the VT signal, extracts changes in the signal, synchronizes with the extracted signal, and operates other circuits; 8 is a power-on reset circuit that initializes each circuit when the power is turned on; 9 is a power-on reset circuit;
A memory circuit 10 stores the input data D _IN when the LO signal is on, and 10 receives the output of the memory circuit 9, synchronizes its output state with the internal clock, and determines the timing for resetting the count control circuit 4. It is a control circuit.

Reference numeral 11 denotes a data generator that generates data to be input to the up-down counter _U1 when the load signal of the up-down counter _U1 is activated, and the data value is determined by the switch _SW2 . That is, the up-down counter U ₁ takes in the data input to the data input terminals D ₁ to _{D 4} using the load signal, thereby obtaining the counter output values Q ₁ to _{Q 4} .
It is now possible to preset. 12 is an AND gate which receives the output of the switching circuit 6 at one input and the output of the power-on reset circuit 8 at the other input, and its output is inputted as a load signal to the load terminal of the up-down counter _U1 . 13 is a brightness information generating circuit which receives brightness information generated by the switch SW ₃ or sent from the CPU (not shown) and outputs either one as brightness information during display. Which signal is used as luminance information is specified by a switch _SW4 .

14 is a zero detection circuit that detects whether the outputs of the up-down counter _U1 are all 0 and resets the count control circuit 4 based on the result; 15 to 17 are switches for the output of the luminance information generation circuit 13;
An AND gate 18 gates the signal from SW ₅ and transmits it to the luminance information synthesis circuit U ₂ , which detects whether the output of the luminance information synthesis circuit U ₂ is the maximum value.
A maximum value detection circuit that resets the count control circuit 4 when the maximum value is reached, that is, when the outputs Q ₁ to _{Q 4} of the luminance information synthesis circuit U ₂ are all "1"; 19 is a signal that resets the count control circuit 4; 20 is a luminance conversion circuit that receives the output (luminance information signal) of the luminance information synthesis circuit U ₂ and converts it into an actual luminance signal. The output of the luminance conversion circuit 20 is sent to a CRT (not shown) as a luminance signal. The operation of the circuit configured as described above will be explained as follows.

First, the case of the first process will be explained. At this time, the light pen (not shown; the same applies hereinafter) is stored in the storage location (not shown), so switch SW ₅ is grounded, and brightness information input B ₁
~ B ₄ are all “0”, and the luminance information synthesis circuit U ₂
prints the lowest value. Therefore, the output of the brightness conversion circuit 20 that receives the output of the brightness information synthesis circuit _U2 also becomes the lowest, and the brightness of the CRT display can be suppressed to a sufficiently low level. FIG. 2 is a timing chart showing the operation of each part at this time. In the figure, A shows the contact state of the switch SW ₅ , B shows the B input of the luminance information synthesis circuit U ₂ , C shows the A input, and D shows its Q output.

A shows a state in which the low level "0" is grounded. When the light pen is stored in the storage location at time t, switch SW ₅ is grounded, the B input of the luminance information synthesis circuit U ₂ becomes 0, and therefore its Q output also becomes 0. . Here, the switch SW ₅ is provided to obtain information as to whether or not the light pen is in the storage location, and is attached to the storage location. When the light pen is retracted, the switch contact is turned on and grounded. As long as the light pen is in the storage location, the brightness information is set to the lowest value. That is,
When the CRT is not in use, lower the brightness as much as possible.
As a result, the lifespan of the CRT will be extended.

By taking out the light pen from the storage location, proceed to the second process. Switch SW ₅ detects that the light pen is removed from its storage location. At this time, AND gates 15 to 17 are all opened, so either the luminance information set by switch SW ₃ or the luminance information transferred from the CPU is sent to the luminance conversion circuit 20 via the luminance information synthesis circuit U ₂ . .
The output of the luminance conversion circuit 20 is sent to the CRT,
A predetermined brightness display is made on the CRT. FIG. 3 is a timing chart showing the operation of each part in this process. The waveforms A to D in the figure correspond to those shown in FIG. In this case, at time _t1 , the A input of the luminance information synthesis circuit _U2 (up-down counter _U1
) becomes 0, and the light pen is removed from its storage location at t ₂ . As a result, the luminance information synthesis circuit
The brightness information output from the brightness information generation circuit 13 is input to the B input of _U2 , and is directly input to the brightness conversion circuit 20 as brightness information, where it is converted into brightness. Therefore,
The CRT will display a brightness according to the brightness information generated by the brightness information generating circuit 13.

When the removed light pen is operated, the aforementioned light pen on signal LO is generated, and this circuit receives the LO signal to proceed to the third process.
During this process, it is necessary to increase the brightness of the CRT to ensure that the light pen position information is input. Brightness information for increasing brightness can be divided into cases where a fixed value is used and cases where variable information is also used.

First, a case where only fixed values are used as luminance information will be described. While the light pen-on signal LO is being accepted by latch circuit 1, the signal
VT passes through the switching circuit 6 and the AND gate 12, and outputs the up/down counter _U1 as a load signal.
given to. Here, the contacts of the switch _SW1 act to use the VT signal as a load signal. For example, when the contact is closed and grounded,
It may be determined in advance to be a load signal.
At the same time, the fixed data set on switch SW ₂ is
Up-down counter U ₁ from data generator 11
are applied to preset inputs D ₁ to _{D 4} . This preset data is taken into the up-down counter _U1 by the previous load signal and is preset. The preset fixed data is output from the up-down counter _U1 and applied to data inputs _A1 to _A4 of the luminance information synthesis circuit _U2 .
This fixed luminance information signal is sent to the luminance information synthesis circuit U ₂
It is combined with the data from the B input and sent to the luminance conversion circuit 20, which provides a luminance signal corresponding to the input signal to the CRT. The CRT has a high-brightness display to accurately detect the position information of the light pen.

FIG. 4 is a timing chart showing the operation of each part at this time. In the diagram, A is a switch.
The contact state of SW ₅ is shown, B is the B input of the brightness information synthesis circuit U ₂ , C is the A input, D is its Q output, E is the VT signal, F is the light pen-on signal, and G is the latch. 1 shows the output of the circuit 1, 1 the output of the AND gate 12, 1 the output of the data generator 11, 2 the output of the pulse generating circuit 2, and 1 the output of the operation control circuit 7. At time _t1 , the switch _SW5 becomes "1" and the brightness information output from the brightness information generation circuit 13 enters the B input of the brightness information synthesis circuit _U2 . Therefore, the Q output terminal of the luminance information synthesis circuit _U2
Data of a constant value is output from _Q1 to _Q4 .
Here, at time _t2 , when the light pen-on signal LO is generated as shown in F, the data generator 11 outputs fixed data as shown in R, and the D inputs _D1 to D of the up-down counter _U1 are output. Enter ₄ . This data is taken internally by the load signal shown in (h). The luminance information synthesis circuit U ₂ combines the output of the up-down counter U ₁ and the luminance information generation circuit 1.
Combine the outputs of 3. Therefore, the luminance information synthesis circuit
The output of U ₂ increases in synchronization with the load signal Q at time t ₃ as shown in D, and the luminance signal is also determined and fixed by this value.

Next, a case where variable brightness information is used in addition to fixed brightness information will be described. At this time, switch SW ₁ of the switching circuit 6,
The VT signal is input to the AND gate 5 as a clock signal. The output change of the latch circuit 1 is converted into a narrow pulse by the subsequent pulse generating circuit 2. This converted pulse sets the count control circuit 4 and makes its Q output "1".
This opens the AND gate 5, and a clock pulse enters the clock input of the up-down counter _U1 , starting a counting operation. The up-down state at this time is the up-down signal generation circuit 3.
is input to the up-down input section of the up-down counter. For example, light pen on signal
It can be configured to give up information when LO is on and down information when it is off. The up-down counter _U1 is cleared by a reset signal from the power-on reset circuit 8 when the power is turned on, and its outputs _Q1 to _Q4 are all initialized to "0". Then, when the LO signal is on, the up-down counter _U1 counts the clock,
Its output increases. At this time, the output of the up-down counter _U1 gradually increases. The luminance information synthesis circuit U ₂ synthesizes the output of this up-down counter and the output from the luminance information generation circuit 13,
Output as a luminance information signal. This output is converted into a brightness signal by the brightness conversion circuit 20 and then
sent to.

While this brightness signal is increasing, the display brightness of the CRT also increases. In this manner, while the input data D _IN is not input to the memory circuit 9, the up-down counter _U1 continues to count up. When the Q outputs Q ₁ to _{Q 4} of the luminance information synthesis circuit U ₂ all become "1", the maximum value detection circuit 18 detects this and resets the count control circuit 4 via the AND gate 19. The count control circuit 4
When is reset, its Q output becomes "0", AND gate 5 closes, and up-down counter _U1 stops counting. Incidentally, when the input data D _IN is input to the memory circuit 9, a control pulse is generated from the timing control circuit 10, and the count control circuit 4 is reset as in the case described above.
Stop the counting operation of up-down counter _U1 . At this point, the output of the up-down counter _U1 is fixed, and therefore the luminance signal output of the luminance conversion circuit 20 is also constant. That is, the CRT display brightness can be fixed by supplying the input data D _IN to the storage circuit 9 when the CRT display brightness reaches a predetermined brightness.

FIG. 5 is a timing chart showing the operation of each part during count-up. In the figure, the waveforms from I to I are the same as those in FIG. H is the output of the up-down signal generation circuit 3, R is the output of the AND gate 5 (clock pulse), N is the output of the AND gate 12 (load signal), R is the output of the maximum value detection circuit 18, W is the AND gate gate 19
The outputs (reset pulses) are shown respectively. At time _t1 , the switch _SW5 is opened, and the brightness information from the brightness information generation circuit 13 is inputted to the B input of the brightness information synthesis circuit _U2 as shown in FIG. As a result, the Q output of the luminance information synthesis circuit _U2 becomes a constant value as shown in d. At time _t2 , the light pen on signal LO turns on (level "1") as shown in F. In response to this, the pulse generation circuit 2 generates a pulse at time _t3 , and sets the count control circuit 4. Then, the Q output is set to "1" and the AND gate 5 is opened. At the same time, up-down signal generation circuit 3
changes from “0” to “1”. As a result, the up-down counter _U1 starts counting up as shown in d. The counting start point is time _t4 when the VT signal enters the up-down counter _U1 from the AND gate 5 as a count clock. Then, when the Q outputs Q ₁ to _{Q 4} of the up-down counter U ₁ all become "1", the maximum value detection circuit 18 operates at time t ₅ as shown in FIG.
Send a reset pulse as shown in 2 to stop the count.

Then, when light pen operation is no longer required, the light pen on signal LO is turned off. When the LO signal turns off, the output of the latch circuit 1 enters the up-down signal generating circuit 3, and the output of the up-down signal generating circuit 3 becomes a down signal and enters the up-down counter _U1 . Therefore, the up-down counter
U ₁ goes into down mode from this point on. At the same time, the count control circuit 4 is set by the pulse generated by the pulse generation circuit 2, and its Q output is set to "1". This opens AND gate 5, and the VT signal sent from switching circuit 6 is applied to up-down counter _U1 as a counter clock. As a result, the up-down counter _U1 starts counting down. Therefore, its output gradually decreases. The output of the brightness information synthesis circuit _U2 , which combines the output of the up-down counter U1 and the output of the brightness information generation circuit ₁₃ , also gradually decreases. Therefore, the output of the brightness conversion circuit 20 that receives the output of the brightness information synthesis circuit _U2 also gradually decreases, and the brightness of the CRT display also becomes lower.
Then, the Q output Q ₁ of the up-down counter U ₁ ~
When _Q4 becomes all "0", the zero detection circuit 14 detects this and resets the count control circuit 4 via the AND gate 19. This results in
The Q output of the count control circuit 4 becomes "0",
Close AND gate 5 and start up/down counter
Stop U ₁ 's counting operation. In this state, the data output from the luminance information synthesis circuit U ₂ is only the luminance information generated by the luminance information generation circuit 13. In other words, only the CRT display is displayed, and the brightness is correspondingly low.

FIG. 6 is a timing chart showing the operation of each part during countdown. In the figure, I to I are the same as FIG. 5. nu is zero detection circuit 1
4 represents the output of AND gate 19, and 1 represents the output of AND gate 19, respectively. At time _t1 , the switch _SW5 is opened, and the brightness information from the brightness information generation circuit 13 is inputted to the B input of the brightness information synthesis circuit _U2 as shown in FIG. As a result, the luminance information synthesis circuit U ₂
The Q output of is a constant value as shown in d. time
At time t ₂ , when the light pen on signal turns off (“0” level) as shown in F, at time t ₃ as shown in G
Then, the output of the latch circuit 1 becomes "0", the output of the up-down signal generation circuit 3 which receives the output of the latch circuit 1 also becomes "0", and the up-down counter
U ₁ goes into down count mode. Therefore, the Q output of the luminance information synthesis circuit U ₂ receiving the output of the up-down counter U ₁ also gradually decreases from time t ₄ as shown in D. Then, when the output of the up-down counter _U1 becomes 0, the zero detection circuit 14 operates at time _t5 as shown in Figure 1, and sends a reset pulse to the count control circuit 4 as shown in Figure 4.
Stop counting.

FIG. 7 is a timing chart showing the operation of each part when input data D _IN is detected. In the figure, I to I are the same as in FIG. wo indicates the output of the pulse generation circuit 2, respectively. During count-up operation, when the data input D _IN is input at time t1 as shown in Figure ₁ , a reset pulse is generated at time _t2 as shown in Figure 4, which resets the count control circuit 4 and stops counting. .

(Effects of the invention) As explained in detail above, according to the invention,
When the operation procedure for combining a CRT and a light pen in a device that uses a combination of a CRT and a light pen is divided into the first to third processes as described above, a detection circuit is provided to detect each of these processes, By generating brightness information according to the output of the detection circuit, the optimum brightness can be automatically set in each process.

[Brief explanation of drawings]

Fig. 1 is an electrical configuration diagram showing an embodiment of the present invention, Fig. 2 is a timing chart showing the operation of each part in the first process, and Fig. 3 is a timing chart showing the operation of each part in the second process. , 4th
The figure is a timing chart showing the operation of each part when a fixed value is input in the third process.
FIG. 6 is a timing chart showing the operation of each part during count-up in the process of count-up, FIG. 7 is a timing chart showing the operation of each part during count-down, and FIG. 7 is a timing chart showing the operation of each part during input data detection. . 1...Latch circuit, 2...Pulse generation circuit, 3
...Up-down signal generation circuit, 4...Count control circuit, 5, 12, 15 to 17, 19...AND gate, 6...Switching circuit, 7...Operation control circuit, 8...Power-on reset circuit, 9 ...Storage circuit, 10...Timing control circuit, 11...Data generator, 13...Brightness information generation circuit, 14...
...Zero detection circuit, 18...Maximum value detection circuit, 20
...Brightness conversion circuit.

Claims (1)

[Claims for Utility Model Registration] A circuit used in a device that uses a CRT in combination with a light pen, where the operating procedure for the CRT and light pen is such that neither the CRT nor the light pen is used, the CRT displays only, the light pen is not used, and the CRT In the case where the operation procedure of the light pen is divided into three steps of use, the method includes a detection circuit that detects each of the steps, and a luminance information generation circuit that generates luminance information according to the output of the detection circuit, An automatic brightness adjustment circuit for a CRT, characterized in that the output of the brightness information generation circuit can be varied according to the three processes described above.