JPH04251836A - Slide projector controlled by midi signal - Google Patents

Abstract

PURPOSE:To control a slide projector synchronizing with playing by utilizing an MIDI signal for controlling an electronic musical instrument. CONSTITUTION:A data for controlling the level of sound volume is extracted out of the MIDI signal inputted by an input port 5 by a selection circuit. Based on the data, a light control circuit 3 controls the light quantity of the slide projector in response to the level of the sound volume.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is directed to MIDI (Mmsic)
al Instrument Digital Int.
The present invention relates to a slide projector that can be controlled by an erface) signal.

0002

2. Description of the Related Art A MIDI signal is a type of control signal for controlling an electronic musical instrument, and its format is determined by a unified standard. MI for electronic musical instruments
A terminal (port) for inputting a DI signal is provided, and when a MIDI signal is input to the electronic musical instrument, the electronic musical instrument automatically performs based on control by the MIDI signal. By supplying music information stored in a computer or sequencer to each electronic musical instrument in the form of a MIDI signal, so-called computer music can be automatically played.

[0003] A system that combines automatic performance with automatic projection using a slide projector has also been developed. Such a system includes a controller that controls the slide projector according to a control signal. Here, the control signal is recorded on the magnetic tape simultaneously with the MIDI signal. This magnetic tape is set in a dedicated tape deck, and the two types of signals mentioned above are read thereby. Among these, MIDI signals are
A corresponding electronic musical instrument is supplied, and a control signal is also supplied to a controller.

0004

SUMMARY OF THE INVENTION In such a conventional system, it is necessary to record MIDI signals and control signals on a magnetic tape in advance, which poses a problem in terms of versatility. Furthermore, in addition to the magnetic tape, a dedicated controller and tape deck are required, which poses problems in terms of structure and cost. Therefore, an object of the present invention is to provide a slide projector that can solve the problems of the conventional example.

[0005]

[Means for Solving the Problems] In view of the above problems, the present invention provides input means for inputting MIDI signals, and input means for inputting MIDI signals.
It comprises a signal detection means for detecting a specific signal from a DI signal, and a signal generation means for monitoring the state of the detected signal and generating a control signal.

[0006]

[Operation] Since the MIDI signal is a signal for controlling an electronic musical instrument, by using this signal, it is possible to control the slide projector in synchronization with the performance of the electronic musical instrument.

[0007]

[Examples] Examples of the present invention will be described below.

First, the MIDI interface will be explained. The MIDI interface has a transfer rate of 3
It operates with asynchronous serial transfer at 1.25 kbit/sec, and when transferring 1 byte (8 bits) of data, a start bit and a stop bit are added, making up 10 bits in total, so 32
It takes 0 μsec. Signal exchange using MIDI signals is performed using multiple byte "messages." The structure of the message is as shown in Figure 1. Except for real-time and exclusive messages, one message includes at least one status byte and one or two messages guided by the status byte. It consists of two data bytes.

FIG. 2 is a functional classification diagram of channel voice messages. Among these, the control change message has a format as shown in FIG. Status byte “BXh” (X is 1ch
The control number byte follows the control number byte and the data byte.

[0010] According to the standard, the control number "7"
Information for controlling the volume of the sound source device (electronic musical instrument, etc.) is assigned to the sound source device, and when the sound source device receives the control message “BXh” “07h” “FFh” in the next data byte, the volume of the sound source device becomes maximum, Control change message “BXh” “07h” “00
When the sound source device receives "h", the volume becomes minimum (no sound is emitted).

FIG. 4 shows a circuit block diagram according to the first embodiment. In this embodiment, the amount of light from a slide projector is controlled by MIDI signals. MIDI
The signal is transmitted via the receiving circuit 1 to the selection circuit 2. The selection circuit 2 extracts a control message from the MIDI signal, further extracts an 8-bit data byte for controlling the volume, and sends it to the dimming circuit 3. The dimming circuit 3 controls the amount of dimming according to the volume level based on the volume control data. Each of these circuits is built into the slide projector 4. The MIDI signal is sent to the port located on the slide projector 4.
It is input from point 5.

Next, regarding the specific configuration of each of the above circuits,
This will be explained below. The receiving circuit 1 is configured as shown in FIG. This configuration is determined by the MIDI interface standard. That is, a 5-pin DIN connector 6, resistors 7 and 8, a diode 9, and a photocoupler 1.
Consists of 0.

The selection circuit 2 is composed of, for example, a one-chip microcomputer, and processes the MIDI signal coming from the input port by software as shown in FIG.
Outputs bit data bytes as parallel data.

The light control circuit 3 is constructed as shown in FIG. Incidentally, a timing chart of signal waveforms of each part is shown in FIG. The AC voltage applied to terminal 11 is full-wave rectified by diode bridge 12 . Transistor 13 creates a zero-crossing pulse from this full-wave rectified signal. This zero-crossing pulse is processed by the waveform shaping circuit 14.
After waveform shaping by transistor 15 and RC
The voltage is applied to a charging/discharging circuit consisting of circuit 16. A charging/discharging circuit generates a sawtooth wave from the zero-crossing pulse. This sawtooth wave is input to one input terminal of the comparator 17. The other input terminal of the comparator 17 has a DC
Voltage is applied. This DC voltage changes depending on the volume level of the MIDI signal, as will be described later. A comparator 17 creates a phase-delayed pulse by chopping the sawtooth wave with a DC voltage. This phase-delayed pulse drives phototriac 18, thereby triggering the gate of triac 19. The light source 20 has a triac 19 triggered (O
It is turned on only during the period (N). In addition,
21 is a snubber circuit for absorbing surges, which is composed of a resistor and a capacitor.

According to this dimming circuit, the comparator 1
The amount of light can be changed in proportion to the level of the DC voltage applied to one input terminal of 7. That is, the greater the DC voltage, the greater the amount of light.

In this embodiment, such DC voltage is
The light of the slide projector is controlled by changing it according to the I signal. Specifically, in the circuit of FIG. 7, the voltage dividing point of the variable resistor 22 that determines the value of the DC voltage is adjusted. An example of such a regulating circuit is shown in FIG. The adjustment circuit includes a decoder 23, a switcher 24, and a plurality of resistors R.
1, R2...Rn. The decoder 23 is an MI
Depending on the 8-bit data that controls the volume of the DI signal, a signal is sent to one of the n+1 switches in the switcher 24 to turn on the switch. When a predetermined switch is turned on, the divided voltage at that point appears at point A. A
The point is connected to one input terminal of the comparator 17. When the volume level based on the MIDI signal is at the minimum value, the decoder sends a signal to the lowest switch in FIG. 9, and from there, as the volume level increases, the signal is sent to the upper switches one by one. Switch. Then, when the volume level based on the MIDI signal reaches the maximum value, a signal is sent to the top switch. When the bottom switch is turned on, the voltage at point A becomes the minimum (zero), and when the top switch is turned on, the voltage at point A becomes the maximum (Vcc).

According to this embodiment, in synchronization with the fade-in and fade-out of music performance using MIDI signals,
The brightness of the projection by the slide projector can be faded in and out.

In the above embodiment, the amount of light of the slide projector is controlled according to the MIDI signal, but other controls of the slide projector are not limited to this.
This may be done by monitoring the DI signal. For example, the slide advance may be controlled in accordance with MIDI signals. Examples related to such slide feeding will be described below.

FIG. 10 shows a slide feeding device for a slide projector. A plurality of slides are set in the Calor cell 31 side by side in the circumferential direction. The slides to be displayed are replaced by stepping the carol cell 31 forward or backward by a stepping motor 32. That is, by moving one step forward, the next slide is displayed, and by moving one step backward, the previous slide is displayed. The stepping motor 32 is fed by receiving forward pulses or backward pulses from the pulse generating circuit 33. The pulse generating circuit 33 generates a forward pulse when terminals 1 and 2 are short-circuited, and generates a backward pulse when terminals 3 and 2 are short-circuited.

[0020] Slide feeding by such a circuit is performed by MI
When controlling using a DI signal, an interface is required to control shorting of the terminals according to the state of the MIDI signal. Such an interface may be built into the slide projector or may be externally attached. As an example of the interface, a signal for controlling the volume level among MIDI signals is monitored as described above, and when the volume level reaches zero, the terminals are short-circuited. As another example, in response to a change (program change) in a MIDI signal that controls the tone (for example, switching the electronic instrument being played from a piano to a violin), terminals are shorted and the slide is switched. Make sure to do the following. For example, the slider may be advanced one step each time the signal controlling the timbre changes, or the slider may be advanced one step each time a specific signal among the signals controlling the timbre is detected. , or back (in this case, there are two types of specific signals corresponding to the front direction and the rear direction).

Further, in all of the embodiments described above, the slide projector is controlled by the state of the signal that directly controls the electronic musical instrument, but among the MIDI signals, the slide projector is not directly involved in controlling the electronic musical instrument. Insert a signal for controlling the slide projector into an empty channel.
The signal may be recorded in advance in the form of an IDI signal, and the slide projector may be controlled in accordance with this signal.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments.
It goes without saying that various other changes are possible.

[0023]

As described above, according to the present invention, by using MIDI signals, it is possible to easily and reliably control a slide projector in synchronization with a musical performance.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the contents of a MIDI signal.

[Figure 2] M
It is a diagram showing the contents of an IDI signal.

FIG. 3 is a diagram showing the contents of a MIDI signal.

FIG. 4 is a block diagram of an embodiment.

FIG. 5 is a diagram showing the configuration of a receiving circuit according to the same embodiment.

FIG. 6 is a flowchart showing the operation of the selection circuit according to the same embodiment.

FIG. 7 is a diagram showing the configuration of a dimming circuit according to the same embodiment.

FIG. 8 is a timing chart of waveforms of various parts related to the tuning circuit.

FIG. 9 is a diagram showing the configuration of an adjustment circuit according to the same embodiment.

FIG. 10 is a diagram showing the configuration of a slide feeding device according to another embodiment.

[Explanation of symbols]

2 Selection circuit (signal detection means) 5 Input port (input means)

Claims (3)

[Claims] [Claim 1] Input means for inputting a MIDI signal;
A slide projector that can be controlled by MIDI signals, and includes signal detection means that detects a specific signal from input MIDI signals, and signal generation means that monitors the state of the detected signal and generates a control signal. 2. The slide projector according to claim 1, wherein the control signal is a signal for controlling the amount of light of the slide projector. 3. The slide projector according to claim 1, wherein the control signal is a signal for controlling feeding of the slide.