JP2503864B2 - Optical switch element drive controller - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical switch element drive control device used in an optical information processing device for processing information by an optical data signal.

[0002]

2. Description of the Related Art An optical switch element whose operating state changes depending on the presence or absence of incident light is under development as a key device of an optical information processing apparatus. Among them, in the optical switch element in which the photodetector function is incorporated in the thyristor structure having the pnpn junction, as shown in the voltage-current characteristic of FIG.
It is possible to switch between a high impedance off state and a low impedance on state. The switch voltage at this time is V ₀ when there is no light incident and V ₁ when there is light incident, and changes depending on the presence or absence of light incident. Therefore, by setting the drive voltage applied to the optical switch element to a set voltage equal to or lower than the switch voltage V ₀ and making light incident with a certain energy or more, the optical switch element can be switched from the off state to the on state. . In this case, the light energy required for switching becomes smaller as the set voltage approaches the switch voltage V ₀ . An optical switch element having a light emitting function can obtain an optical output in an ON state and can function as an optical logic element. The switching to the off state is executed by setting the drive voltage to the reset voltage equal to or lower than the hold voltage V ₂ (for example, refer to the optical logic element described in Japanese Patent Application Laid-Open No. 1-2221727).

Such an optical switching operation can be realized by an LED element or an element in which a laser element and a phototransistor are combined.

[0004]

In an optical information processing apparatus, a clock operation is normally performed. However, in the above optical switch element, as shown in FIG. 5, for example, as shown in FIG. A clock pulse, which is a drive voltage in which the set voltage and the reset voltage are alternately repeated, is applied, and switching control is performed by the optical input 4. The signal timing in this case is illustrated in FIG. When the frequency of the clock pulse applied to the optical switch element 1 becomes high,
Since the application time of the reset voltage becomes short, it becomes difficult to shift the optical switch element 1 to a sufficiently off state,
Along with that, the switch voltage of the optical switch element 1 decreases. This is because if the reset operation is insufficient, residual carriers are generated inside the optical switch element 1. When the switch voltage thus decreases, the light energy required for switching decreases, so that the time from the rise of the pulse of the optical input 4 to the rise of the pulse of the optical output 14 changes as shown in FIG. End up (t ₁ ＞
t ₂ ). The pulse width of the optical output 14 also changes accordingly, but such fluctuations in the pulse width cause instability when performing the clock synchronization operation.

An object of the present invention is to provide an optical switch element drive control device which solves such problems and can obtain a stable optical output with a pulse width.

[0006]

An optical switch element drive controller according to the present invention is an optical switch element that performs a switching operation in response to a drive voltage and an optical input of a certain value or more, and the optical switch element has the optical input. A control means for generating a control signal for setting the drive voltage so that the operating time is adjusted to a predetermined length according to the length of the operating time until the optical pulse is started to be output in response to the pulse rise of Drive means for setting the drive voltage according to the control signal and applying the drive voltage to the optical switch element.

[0007]

In the present invention, as shown in FIG. 1, in addition to the optical switch element 1 and the drive circuit 2, a pulse width detection circuit 3 for detecting the operating time of the optical switch element 1 is provided. The pulse width detection circuit 3 detects the pulse width of the optical output 14 in the past clock cycle of the optical switch element 1 and changes the set voltage output from the drive circuit 2. When the pulse width is increased, the set voltage is decreased, and when the pulse width is decreased, the set voltage is increased, thereby decreasing or increasing the residual carriers in the optical switch element 1 at the time of resetting, and thereby the optical input. Optical output 1 from pulse rise of 4
It is possible to stabilize the time length until the rise of pulse No. 4 of FIG.

[0008]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. The optical switch element drive controller of the present embodiment detects the response time of the optical switch element 1, the drive circuit 2 for applying a drive voltage thereto, and the optical output 14 from the optical switch element 1 with respect to the optical input 4. And a pulse width detection circuit 3 for controlling the drive circuit 2. Optical switch element 1
For this, a combination of a pnpn junction structure and a light emitting / receiving function is used.

FIG. 2 is a block diagram showing a detailed configuration example of each circuit of this embodiment. In the pulse width detection circuit 3, the optical output detection circuit 5 outputs the output light 14 of the optical switch element 1.
Pulse is detected and converted into an electric pulse, and the pulse width measuring circuit 6 detects the width of the electric pulse by counting the clock pulse from the clock circuit 8. In response to the detected pulse width, control signal generation circuit 7 reads and outputs a digital signal representing a set voltage stored in advance. In the drive circuit 2, the set voltage generation circuit 9 converts the digital signal of the set voltage into an analog voltage and sends it to the changeover switch 11. The reset voltage generating circuit 10 outputs a constant voltage, and the switch 11 switches between the constant voltage and the output voltage from the set voltage generating circuit 9.
And the drive voltage applied to the optical switch element 1 is generated. The clock circuit 8 generates a clock pulse indicating the operation timing of each circuit.

FIG. 3 is a signal timing diagram illustrating the operation of this embodiment. When a clock pulse having a fixed cycle and a duty ratio is used as a drive voltage, FIG.
As described above, when the reset operation becomes inadequate, residual carriers are generated in the optical switch element 1, the pulse rise of the optical output 14 occurs earlier, and the pulse width of the optical output 14 increases. In this embodiment, the pulse width detection circuit 3
When the pulse width detection result of the pulse width measuring circuit 6 increases (decreases), the set value instruction value sent from the control signal generating circuit 7 to the set voltage generating circuit 9 of the drive circuit 2 is V
Decrease (increase) from _a to V _b . As a result, the optical energy required for switching to the ON state becomes large (small), so that the pulse rise of the optical output 14 is prevented from being early (late), and the optical output 1 having a stable pulse width is provided.
4 is obtained.

In the present embodiment, the set voltage is lowered according to the increase / decrease of the pulse width of the optical output 14, but it is not necessary to limit to such control. For example, the set current is decreased according to the increase or decrease of the current flowing through the optical switch element 1, or the set voltage is changed according to the increase or decrease of the time from the pulse rise of the optical input 4 to the pulse rise of the corresponding optical output 14. Easy to configure to raise and lower,
It is obvious that the same effect as that of this embodiment can be obtained.

[0013]

As described above, according to the present invention, it is possible to realize an optical switch element drive control device in which the switching operation time is stabilized.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

2 is a block diagram showing a detailed configuration of a drive circuit 2 and a detection circuit 3 in FIG.

FIG. 3 is a signal timing diagram illustrating the operation of one embodiment of the present invention.

FIG. 4 is a characteristic diagram showing voltage-current characteristics of an optical switch element used in a conventional device and an embodiment of the present invention.

FIG. 5 is a block diagram showing a conventional device.

FIG. 6 is a signal timing diagram illustrating the operation of a conventional device.

[Explanation of symbols]

 1 Optical Switch Element 2 Drive Circuit 3 Pulse Width Detection Circuit 4 Optical Input 5 Optical Output Detection Circuit 6 Pulse Width Measurement Circuit 7 Control Signal Generation Circuit 8 Clock Circuit 9 Set Voltage Generation Circuit 10 Reset Voltage Generation Circuit 11 Changeover Switch 14 Optical Output

Claims (2)

(57) [Claims] 1. An optical switch element that performs a switching operation in response to a drive voltage and an optical input of a certain value or more, and until the optical switch element starts to output an optical pulse in response to a pulse rise of the optical input. Control means for generating a control signal for setting the drive voltage so that the operation time is adjusted to a predetermined length in accordance with the length of the operation time; and the drive voltage is set according to the control signal to set the optical voltage. An optical switch element drive control device, comprising: a drive unit for applying to the switch element. 2. The control means includes pulse width detection means for detecting the pulse width of the output light of the optical switch element, and control signal generation means for generating the control signal according to the detection result. 1. The optical switch element drive control device according to 1.