JPH087239B2 - Character display device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a character display device used in an oscilloscope or the like.

2. Description of the Related Art In recent years, oscilloscopes are increasingly displaying characters and cursors to facilitate measurement. However, in a real-time oscilloscope, characters and cursors are drawn while drawing the observed waveform, so time-sharing the electron beam of the CRT is inevitable. As a result, when the frequency of the observed waveform is close to the division frequency of the electron beam, the observed waveform is drawn as a discontinuous bright line and is very difficult to observe.

FIG. 5 shows a conventional example. The operation will be described with reference to the waveforms of each part in FIG. Since the basic part of the oscilloscope has been known for many years, only the essential points will be explained.

The observed waveform a applied to the vertical axis input channel 1 input terminal 1 or the vertical axis input channel 2 input terminal 4 is vertically adjusted by increasing or decreasing to a desired amplitude in the vertical axis channel 1 circuit 2 or the vertical axis channel 2 circuit 5. It is added to the axis channel switching circuit 3 and selectively enters the vertical axis signal delay circuit 6. The observed signal that has obtained the required delay amount is the vertical axis signal / character switching circuit 7
In accordance with the character display switching signal f, the character display vertical axis signal g is alternately switched to form a combined vertical axis signal / character switching circuit output signal i which is added to the vertical axis output amplifier circuit 8 and the cathode ray tube 9 It is amplified to the amplitude required by the and is applied to the vertical axis deflection plate of the cathode ray tube 9.

Generally, the observed signal a is input to the main sweep sync signal input terminal 10.
A signal similar to the above is given from the vertical axis circuit, a synchronizing pulse b is generated at the time when the synchronizing level v _t is reached in the main sweep quote synchronizing circuit 11, and the main sweep signal c is added to the main sweep sweep signal generating circuit 12. appear. This part of the main sweep signal c is applied with delay position level voltage v _d to a comparison circuit 13 for sweep delay time generating generates a delay time signal d, the delay for sweeping sweep signal generator with the output of the delay sweep synchronization circuit 15 It is applied to the circuit 16 to generate a delayed sweep signal e. The main sweep signal c and the delayed sweep signal e are selectively added to the horizontal axis signal / character switching circuit 18 through the horizontal axis signal switching circuit 17, and the character display switching signal f is used between them and the character display horizontal axis signal h. The horizontal axis signal / character switching circuit output signal j, which is switched alternately, is added to the horizontal axis signal switching circuit 17, amplified to the amplitude required by the cathode ray tube 9, and applied to the horizontal axis deflection plate of the cathode ray tube 9.

Erase signal n within vertical axis signal switching period obtained from vertical axis channel switching circuit 3, main sweep gate signal obtained from main sweep reference signal generation circuit, and delayed sweep reference sweep signal generation circuit
The delayed sweep gate signal m obtained from 16 is added to the brightness control signal switching circuit 21 together with the external signal from the brightness control external signal input terminal 20 and switched between the character display brightness control signal and the character display switching signal f. The brightness control signal / character switching circuit output signal i is formed into an amplitude necessary for brightness control of the cathode ray tube 9 in the luminance control signal amplifier circuit 22 and added to the first grid of the cathode ray tube 9. . The various character signals f, g, h, and o described above are the character signal generation circuit 2
The control system circuit 30 is mainly made up of the CPU through the control system bus 29.
Instructed by.

However, the observed signal waveform and the character display are as shown in FIG. 8. In order to display the character during the period of drawing the observed signal waveform depending on the sweep speed and timing. The part where the bright line is cut off is very conspicuous, which hinders the observation. Especially when the observed signal waveform is expanded in the horizontal axis direction by using the delayed sweep function, the dot period of the character signal often becomes close to the sweep time, and as shown in FIG. It will cause a fatal obstacle.

An object of the present invention is to alleviate and remedy such conventional drawbacks, and it is an object of the present invention to provide an excellent character display device with few missing bright lines even when displaying characters and cursors together with signal waveforms.

Means for Solving the Problems In order to solve the above problems, the present invention provides an oscilloscope having a delay sweep means for delay sweeping an observed signal waveform and a means for displaying character information in a time-division manner, for displaying the character information. Storage means for storing in a region corresponding to the screen position, a clock control circuit for stopping the supply of the character display clock signal during the delay sweep gate signal of the delay sweep means, and the display according to the character display clock signal. Counter circuit for controlling the character display position for outputting a character position signal corresponding to the screen position for the display, and the character information stored in the storage means are sequentially read from the area corresponding to the output value of the counter circuit, and the character information is read out. Character signal generating means for exchanging and outputting a vertical axis signal for display and a horizontal axis signal for character display, and character display based on the output of the counter circuit Brightness control circuit for outputting a luminance signal for display, a character display switching signal output circuit for outputting a character display switching signal based on the output of the counter circuit, and an observed waveform display luminance signal by the character display switching signal And a luminance switching circuit for switching the luminance signal for character display.

Therefore, the present invention stops the generation of the character display signal during the delayed sweep period so that the characters before and after the stop period are continuously displayed, and further, for the observed signal measurement waveform and the character display. Since the luminance signal is switched and displayed, it is possible to eliminate the discontinuity of the observed signal waveform due to the character display function in the delayed sweep magnified display, and to maintain constant luminance without flickering the observed signal waveform and the character display. Can be displayed.

Embodiment FIG. 1 is a block diagram showing an embodiment of the present invention.
Except for the thick solid line part, it is exactly the same as FIG. 5 of the conventional example. The thick solid line portion will be described.

A part of the delayed sweep gated signal m is supplied to the character signal generation circuit 24 or the character display switching limiting gate 50 for suppressing the character display switching signal f to prohibit the character display operation during the delayed sweep period. This solves the problem that the waveform of the observed signal is interrupted due to the character display function in the delayed sweep enlarged display shown in FIG. In addition, the delayed sweep period is usually about 1/2 times higher than the main sweep period, and even if the characters are not displayed during the delayed sweep period, the character display on the CRT screen is at least 70% or more in character brightness. Can be maintained
Also, the letters are not missing.

FIG. 1 is a block diagram showing the concept of the present invention, FIG. 2 is an embodiment of the main part of the present invention centering on the character display circuit part, and FIG. 3 is a concrete embodiment of the concept shown in FIG. FIG. 4 is a signal waveform diagram showing an operation example of FIGS. 2 and 3 as a specific example.

The present invention will be described below with reference to FIGS. Among the numbers indicating the respective parts and the characters indicating the signals in the drawings, 1 to 30 and a to which are the same as those in FIGS.
Since o indicates the same function, its repeated description will be omitted. That is, the present invention shown in FIGS. 1 and 2 is obtained by modifying or adding a part of the conventional example shown in FIG. Therefore, it is judged that there is no problem even if the explanation is limited to the changed / added parts.

The difference between FIG. 1 and FIG. 5 is that the delayed sweep gate signal m is supplied to the character signal generating circuit 24 to form a new character signal generating circuit 24a.

A detailed configuration centering on the new character signal generation circuit 24a will be described with reference to FIG. 2. The character display information r sent from the control system circuit 30 mainly of the CPU through the control system bus circuit 29 is the character information reception register 41. And the control commands α, β, γ, which are also received by the character information reception register 41.
It is stored / written in the character display screen configuration RAM 42 by the character display screen configuration RAM control signal γ in δ and ε. When this memory writing operation is completed, the coded character signal g, which is the character information stored in the character display screen configuration RAM 42, is read and encoded in accordance with the character position signal p output from the character display position control counter 43. It is supplied to the ROM 44 for converting a character signal to a character display signal, converted into a character display signal s necessary for vector display, and then entered into the character display signal transmission latch 45. The character display signal transmission latch 45 removes the transient signal disturbance generated by the ROM 44, and outputs two digital-analog converters for generating an analog vector signal for actually displaying the character. Hereinafter referred to as DAC) 46,
Supply to 47. The output t of the latch 45 is divided into two parts, while the character position signal p from the character display position control counter 43 is also divided into two parts, which become a character display vertical position control signal u and a character display horizontal position control signal v, respectively. It is supplied to the vertical axis signal generating DAC 46 and the character display horizontal axis signal generating DAC 47. Thus, the character display vertical axis signal output circuit 25 and the character display horizontal axis signal output circuit 26 receiving the outputs of the two DACs 46 and 47 respectively obtain the character display vertical axis signal g and the character display horizontal axis signal h. .

Here, the character display position control counter 43 receives the character display clock signal 49 via the character display clock signal control circuit 48 and sequentially generates the position data necessary for character display. Since the circuit 48 receives the delayed sweep gate signal 50 and suppresses sending of the clock signal from the time t _s to the time t _e which is the delay sweep period, the operation progress of the character display position control counter 43 also progresses from the time t _s. The operation is stopped during t _e , and the character display switching signal output circuit 28 that receives one of the outputs is also stopped during the time t _s to t _e for outputting the signal for displaying characters.

FIG. 3 is a specific example of FIG. 2, and the operation of FIG. 4 will be described in more detail.

The character display clock signal control circuit 48 is composed of the NOR gate U7, and the time t _s when the delayed sweep gate signal m is in the high level.
During the period from to t _e , the character display clock signal 49, which is also the input of the NOR gate U7, is prevented from being transmitted to the output of the NOR gate U7. The output of the NOR gate U7 is supplied to the counter U8 and U19 of the character display switching signal circuit 27, but during the time t _s to t _e , the clock signal supply is stopped as described above, so all operations for displaying characters are performed. Is canceled. Immediately after the time t _e , the supply of the clock signal is restarted again, and the character display operation is restarted.

In this way, it is possible to mitigate the disadvantage that the operation of character display is interrupted between the time t _s and t _e , that is, the period of the delayed sweep, and the observed signal waveform is cut off for the character display function.

As is apparent from the above embodiment, the present invention stops generation of the character display signal during the delayed sweep period so that the characters before and after the stop period are continuously displayed, and further, the observed signal Since the luminance signal is switched and displayed for the measured waveform and the character display, it is possible to eliminate the interruption of the observed signal waveform due to the character display function in the delayed sweep magnified display, and to display the observed signal waveform and character display. It has an effect that it can be displayed with constant brightness without flickering.

[Brief description of drawings]

FIG. 1 is a block diagram of an oscilloscope including a character display device according to an embodiment of the present invention, FIG. 2 is a block diagram of a character signal generating circuit according to the same embodiment, and FIG. 3 is a specific circuit diagram of FIG. FIG. 4 is a signal waveform diagram of the same embodiment, FIG. 5 is a block diagram of a conventional example, FIG. 6 is a signal waveform diagram of the conventional example, FIG. 7 is a display screen diagram in which characters and signal waveforms overlap, and FIG. The figure is a general display screen diagram. 7 ... Vertical axis signal / character switching circuit, 9 ... CRT,
12 …… Main sweep quote sweep signal generation circuit, 16 …… Delayed sweep quote sweep signal generator circuit, 17 …… Horizontal axis signal switching circuit, 18 …… Horizontal axis signal / character switching circuit, 21 …… Brightness control signal switching circuit , 24a …… Character signal generation circuit.

Claims (1)

[Claims] 1. An oscilloscope having a delay sweep means for delay sweeping an observed signal waveform and a means for displaying character information in a time-division manner, and a storage means for storing the character information and a delay sweep gate signal of the delay sweep means. A clock control circuit that stops the supply of the character display clock signal during the period,
A counter circuit for character display position control that outputs a character position signal according to the character display clock signal, and the character information stored in the storage means are sequentially read in correspondence with the output value of the counter circuit. To a character display vertical axis signal and a character display horizontal axis signal for output, a brightness control circuit for outputting a character display brightness signal based on the output of the counter circuit, and the counter circuit A character display switching signal output circuit that outputs a character display switching signal based on the output of the character display, and a luminance switching circuit that switches the observed waveform display luminance signal and the character display luminance signal by the character display switching signal. Equipped character display device.