JPS6232493B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention specifies an arbitrary point on a screen on which an image (image on a CRT screen, etc.) is projected by scanning from a remote location, and creates an X, Y coordinate signal of the point. In addition, the created coordinate signal is
The present invention relates to a remote instruction input device for inputting information to a device for displaying a cursor at the indicated point.

Such a remote instruction input device is effective when applied to a video screen used in place of a blackboard at a conference table, etc., and a conventional example thereof is shown in FIG.

In FIG. 1, 1 is a video screen, 2 is a scanning light, 3 is a remote instruction input device, 4 is a processing device,
5 is a video signal, 6 is a CRT screen projection device, 7 is a cursor, and 8 is a scanning direction.

Here, the CRT screen projection device 6 has a function of converting the input video signal 5 into a scanning signal for image formation, and its principle is well known in devices such as televisions. However, in television, an electron beam is irradiated onto a fluorescent surface inside a cathode ray tube to emit light and form an image.
A CRT screen projection device 6 irradiates scanning light onto a video screen 1, which is different from a television.

The remote instruction input device 3 corresponds to an input section of a device that detects the reflected light 2 of the scanning light on the screen 1 and displays a cursor (position instruction mark) 7 at the detected position on the screen. Using the output from the remote instruction input device 3 as timing, the processing device 4 outputs a video signal for cursor display to the projection device 6.

As shown in FIG. 2, the circuit configuration of such a remote instruction input device 3 conventionally consists of an optical sensor 31, a comparator 32, a detection signal from the optical sensor 31 via the comparator 32, and scanning in the horizontal and vertical directions. AND circuit 33 that matches the synchronization signal
It was composed of. That is, the optical sensor 31 detects the reflected light of the scanning light, and the detected light is sent to the comparator 3.
2, and when the voltage exceeds the voltage V, a pulse is output. This pulse output is then used as a coordinate signal for the marker, but since the distance between the video screen and the remote instruction input device is not always constant and varies depending on how it is used, it is subject to changes in usage conditions and the surrounding environment. Due to changes in environmental conditions such as changes in lighting, noise may be mixed into the detection signal that detects the scanning light, causing problems such as flickering of the cursor display that specifies the coordinate position of the indicated point on the screen. Ta.

The present invention has been made to improve the problems of the prior art as described above, and therefore, an object of the present invention is to prevent the cursor display on the screen from flickering regardless of changes in usage conditions or environmental conditions. The object of the present invention is to provide a remote instruction input device that does not require manual input.

In order to achieve the above object, the present invention specifies an arbitrary point on a screen on which an image is projected by scanning from a remote location, creates a coordinate signal of the point, and transmits the created coordinate signal to the A remote instruction input device input to a device for displaying a cursor at a designated point, comprising means for detecting scanning light at the indicated point, and means for converting a detection signal from the means into an analog/digital (A/D). and,
an integrating means for counting the converted digital signal and outputting an integral value of the detection signal; a pulsing means for generating a pulse output when the integral value exceeds a certain set level; means for synchronizing and outputting coordinate signals by performing phase comparison with scanning synchronization signals of horizontal and vertical terminals of scanning, and means for averaging time intervals of the coordinate signals outputted in time series to make them constant intervals. It is characterized by consisting of.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a block diagram showing one embodiment of the present invention. In the figure, 11 is an optical sensor that detects scanning light, 12 is a differentiating circuit that removes the DC component of the detection signal from the optical sensor 11, 13 is a smoothing circuit that smoothes the output of the differentiating circuit, and 14 is the smoothing circuit output S ₁
15 is an A/D converter for converting the sampled signal from analog to _digital , and 16 is a sampling circuit whose magnitude changes with time. a counter for counting the total amount (digital amount); 17 is a depth switch, for example, for setting a threshold;
18 is an AND gate (digital comparator) for comparing the value V ₁ set by the depth switch 17 and the counter output value S ₃ ; 19 is a phase comparison between the vertical scanning synchronization signal S ₄ and the output of the AND gate 18 PLL (phase locked loop) circuit for synchronization, 20 is a horizontal scanning synchronization signal
A PLL circuit performs synchronization by comparing the phases of S ₆ and the output of the AND gate 18; 21 is a waveform shaping circuit for shaping the pulse waveform of the PLL circuit output; 2
Reference numeral 2 denotes a constant periodization circuit that averages the period of the pulse signal obtained in time series through the PLL circuit and the waveform shaping circuit to a constant period.

FIG. 4 is a time chart of various signals in the circuit of FIG. 3.

FIG. 5a is an explanatory diagram showing the range M in which the optical sensor 11 detects scanning light on the screen 1, and FIG. 5b
2 is a waveform diagram showing the waveform of a detection signal output from the optical sensor 11. FIG.

The operation of one embodiment of the present invention will be described with reference to FIGS. 3 to 5.

As shown in Figure 5a, the scanning light on the video screen 1 is first scanned in the horizontal direction with the upper left corner as a reference, and after reaching the right edge, it moves downward by one scanning pitch and moves from the coordinates of the left edge. The image is displayed by repeating the process of scanning rightward again. At this time, the signal detected by the optical sensor 11 is a signal obtained by scanning the detection range M indicated by diagonal lines in FIG.
It is detected as a waveform as shown in Figure b.

Such a detection signal contains noise due to the influence of ambient light, the light receiving conditions of the optical sensor 11, etc., and it is necessary to take measures to improve the S/N ratio.

In FIG. 3, the signal detected by the optical sensor 11 has a low S/N ratio due to the above-mentioned circumstances, so first, the differentiating circuit 12 cuts out the DC component, thereby reducing the amount of ambient light. Remove influence. Next, a differentiating circuit 1 is used to remove irregular harmonic components included in the detection signal and obtain a stable detection signal.
The output signal of step 2 will be integrated, but if the output signal of the differentiating circuit 12 is simply integrated, its positive and negative values will be canceled out, so it is smoothed through a smoothing circuit (bridge) as shown in step 13. do. The integration circuit for integrating this smoothed output can be easily realized using an analog circuit, but
If realized in a form that also has the function of D conversion, the circuit configuration I will be, for example, as shown by the broken line in FIG.

In other words, the integrating circuit I outputs the output S ₁ of the smoothing circuit 13.
a sampling circuit 14 that samples with a timing signal _S2 having a constant period, an A/D converter 15 that A/D converts the sampling output, and a counter that counts the converted digital amount and outputs an integral value _S3. It consists of 16.

Note that the signals S ₁ , S ₂ , and S ₃ are as shown in the time chart of FIG. 4.

Returning to FIG. 3, the integral value output signal _S3 is compared in the AND gate 18 with the _V1 level signal set by the depth switch 17, and when it exceeds the _V1 level, the integral value output signal S3 is outputted as a logic "1" level signal. Output.

Here, the magnitude of the level V ₁ may be determined in accordance with the maximum peak of the output signal S ₁ of the smoothing circuit 13, for example, and the magnitude of the peak when the distance between the screen and the optical sensor changes. Changes can be dealt with by manually adjusting the setting level of the depth switch 7.

The output signal of the AND gate 18 is phase-aligned with the vertical scanning synchronization signal S ₄ and the horizontal scanning synchronization signal S ₆ in PLL circuits 19 and 20. By using this signal, it is possible to obtain the coordinate signal of the indicated point where the cursor on the screen should be generated in synchronization with the scanning synchronization signal, so if the coordinate (specified) signal is out of synchronization, the screen The flickering of the cursor that occurs on the screen can be improved.

Note that the outputs of the PLL circuits 19 and 20 are shaped into a waveform having a prescribed pulse width by a waveform shaping circuit 21 such as a monostable multivibrator. The output signal that has been subjected to such waveform shaping processing is synchronized by comparing the phase of the vertical scanning synchronization signal _S4 and the output signal of the AND gate _18.S5 in FIG. The waveform will look like this. Note that this output signal _S5 is also used to reset the counter 16.

Next, the constant periodization circuit 22 is for making the waveform shaping output _S5 a constant period when it is no longer generated at a constant period due to fluctuations in the integral signal _S3 .

If the integral signal _S3 changes as shown in _FIG . change,
The phase difference Δt between ' and ' will change the coordinate position of the cursor. This results in variations in the cursor position as shown in FIG. 6b. Here, in order to reduce the influence of Δt, it is necessary to count the time intervals between multiple time-series signals _S5 obtained by multiple scans, and select and use the average value. Therefore, the signal _S5 may be always obtained at a constant period. It goes without saying that the periodicization circuit used for this purpose can be easily constructed by using a shift register or the like.

As described above, the present invention has the advantage that it is possible to provide a highly accurate remote instruction input device in which the cursor display on the screen does not flicker regardless of changes in usage conditions or surrounding environment.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a conventional example of a remote instruction input device, FIG. 2 is a circuit diagram showing a circuit configuration of a conventional remote instruction input device, and FIG. 3 is a block diagram showing an embodiment of the present invention. Figure 4 is a time chart of various signals in the circuit of Figure 3, Figure 5a is an explanatory diagram showing the range M in which the optical sensor detects the scanning light on the screen, and Figure 5b is the detection signal output by the optical sensor. Figure 6a is a time chart showing changes in the coordinate signal that occur when the integral signal fluctuates depending on the waveform of the detection signal, and Figure 6b is an explanatory diagram showing variations in the cursor position at that time. , is. Description of symbols, 1...Video screen, 2...Scanning light, 3...Remote instruction input device, 4...Processing device, 5...Video signal, 6...CRT screen projection device, 7...Cursor, 8... ...Scanning direction, 11...
Optical sensor, 12...Differential circuit, 13...Smoothing circuit, 14...Sampling circuit, 15...A/D
Converter, 16... Counter, 17... Deep switch, 18... AND gate, 19, 20...
PLL circuit, 21... Waveform shaping circuit, 22... Fixed period circuit, 31... Light sensor, 32... Comparator, 33... AND circuit.

Claims (1)

[Claims] 1. Indicate an arbitrary point on the screen on which an image is projected by scanning from a remote location, create a coordinate signal of the point, and use the created coordinate signal to
A remote instruction input device input to a device for displaying a cursor at the indicated point, the remote instruction input device comprising means for detecting scanning light at the indicated point, and converting a detection signal from the means into an analog/digital (A/D). means for counting the converted digital signal and outputting an integral value of the detection signal; pulsing means for generating a pulse output when the integral value exceeds a certain set level; a means for performing a phase comparison with horizontal and vertical scanning synchronization signals of the image scanning to synchronize the coordinate signals and outputting the coordinate signals; 1. A remote instruction input device comprising: