JPS6210931A - Data transmission equipment - Google Patents

Abstract

PURPOSE:To make signals transmitted to a telephone circuit uniform at all times by simple constitution by providing a level adjusting circuit controlled by an input signal of a conversion means in an output side of a signal conversion means. CONSTITUTION:When the value of a variable resistance VR1 is made larger than the value of a variable resistance VR2, the TR2 becomes on and TR3 becomes off at the moment when the data signals are low level. Accordingly, attenuation of the signals caused by the level adjusting circuit becomes relatively large. Therefore, the signals are amplified by the TR1 and signals shown in the figure C are outputted. Thereby, signals transmitted to telephone circuits L1, L2 become nearly uniform level as shown in the figure D.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a data transmission device for transmitting data to a handset such as a telephone via an acoustic coupling device in a portable data terminal device or the like.

BACKGROUND TECHNOLOGY In general, in portable data terminal devices, etc., when the page data is input to the handset of a telephone via an acoustic coupling device and transmitted to a computer at a center via the telephone or telephone line, the method shown in Fig. 3 is used. As shown in FIG. 4, a signal conversion means ■C1 composed of a microcomputer or the like is used to convert the data signal shown in FIG. 4A inputted to the input terminal a into the data signal shown in FIG. This is converted into a signal and applied to the speaker SP constituting the acoustic coupling device via a reduction filter for high frequency component removal consisting of a coupling capacitor CI, a resistor RI, a capacitor 02, etc., a transistor TR, and a transformer T1. from the telephone installation, to the microphone MIC in the handset H8+, telephone installation I, telephone line Ll.
, L2 to the center computer, etc.

Problems to be Solved by the Invention However, in this type of device, the signal converting means IC,
As shown in FIG. 4B, when the data signal is at a high level and when it is at a low level, the frequency of the data signal is converted into a signal with different frequencies. If there is a frequency characteristic in the sensitivity of the telephone line LIs, even if the sound from the speaker SP is of a uniform level as shown in Figure 4C,
As shown in Figure 4, the signal transmitted to L2 has a much lower level when the data signal is high level than when it is low level, and there is a problem that it cannot be accurately received by the central computer, etc. there were.

The present invention is intended to eliminate the above-mentioned conventional drawbacks, and an object of the present invention is to provide an excellent data transmission device that can always make uniform signals transmitted over a telephone line with a simple configuration. It is.

Means for Solving the Problems In order to achieve the above object, the present invention provides a level adjustment circuit on the output side of the signal conversion means that is controlled by the input signal of the conversion means, and this level adjustment circuit adjusts the frequency characteristics of the telephone. This structure is designed to compensate for level fluctuations due to

Therefore, according to the present invention, signals of a uniform level can always be transmitted to the telephone line, and these signals can be accurately received by a central computer or the like on the receiving side.

Embodiment FIG. 1 is an electrical connection diagram of an embodiment of the data transmission device of the present invention. In FIG. 1, the same reference numerals as in FIG. 3 indicate the same components as in FIG. Then, R2 is a resistor connected between the coupling capacitor C1 and the resistor R1, and V R+ and VH2 have one end connected to the resistor R+ and the resistor R2.
are connected to the connection point of each transistor TR
2. It is a variable resistor grounded via TR3.

The transistors TR2NTR3 are configured to be turned on and off by the data signal applied to the input terminal a and the output of the phase inversion circuit IC2, respectively, and these transistors TR2, TR3 and the resistor R2,
Variable resistors VR, , VR2i constitute a level adjustment circuit.

In the above embodiment, if a data signal as shown in FIG. 2A is input to the input terminal a, a signal as shown in FIG. 2B is outputted to the output side of the signal converting means IC+. Then, the signal is passed through the coupling capacitor CI to the transistors TR2, T Rs, the resistor R2, and the variable resistor V.
The signal is applied to a level adjustment circuit consisting of R, , and VH2, where the level is adjusted. That is, suppose that the value of the variable resistor VRI is set to be thicker than the value of the variable resistor VR2. At the moment when the data signal is at a high level, the transistor T R2
is turned on and transistor TR3 is turned off, so that the level adjustment circuit is essentially constituted by the resistor R2 and the variable resistor vRI, and the attenuation of the signal by the level adjustment circuit is relatively small. At the moment when the data signal is at a low level, the transistor TRs is turned on and the transistor TR2 is turned off, so that the level adjustment circuit essentially consists of the resistor R2 and the variable resistor VR.

The level adjustment circuit 6
Attenuation of the signal by the page is relatively large. Therefore, when these signals are amplified by the transistor TR and applied to the speaker SP via the transformer T1, the speaker SP outputs a signal as shown in FIG. 2C. Therefore, even if there is a frequency characteristic that attenuates low frequency signals more in the telephone equipment, the signal transmitted to the telephone line L11L2 will be at a uniform level as shown in Figure 2, and the center signal will be at a uniform level. It is possible to completely prevent the problem that computers, etc., cannot receive accurate reception.

In the above explanation, we have explained the case where the telephone equipment has the characteristic of attenuating low frequency signals more (or amplifying high frequency signals more greatly), but in the opposite case, the telephone line The level of the signal transmitted to L11L2 can be made uniform.In other words, in this case, the value of variable resistor VR,
It may be made smaller than the value of R2.

Page 7 Effects of the Invention As is clear from the above embodiments, the present invention provides a signal converting means that inputs a data signal and outputs signals of different frequencies depending on whether the level of the data signal is high level or low level. A level adjustment circuit whose signal attenuation rate is switched according to the level of the data signal is provided on the output side of the data signal, and this level adjustment circuit compensates for level fluctuations due to the frequency characteristics of a telephone, etc. connected to the subsequent stage. The signal transmitted to the telephone line will be at the same level at any moment when the data signal level is high or low, making it impossible for the receiving side to receive these signals accurately. This has the advantage that it can be easily prevented.

[Brief explanation of drawings]

FIG. 1 is an electrical connection diagram of one embodiment of the data transmission device of the present invention, FIG. 2 is a signal waveform diagram of each part of the device, and FIG.
The figure is an electrical connection diagram of a conventional data transmission device, and FIG. 4 is a signal waveform diagram of each part of the device. ICI...Signal conversion means, Ic2...Phase conversion means, CI...Coupling capacitor NRI
, C2... Resistor, capacitor, R2, V R+ , V R2... Resistor, variable resistor, TRI-T forming the level adjustment circuit.
R3...Transistor, TI...Transformer, SP...Speaker constituting the acoustic coupling device, Hs Bi-ring...Handset, T...Telephone , LI, L2...Telephone line. Name of agent: Patent attorney Toshio Nakao
Yuu 0 ρ faction

Claims (1)

[Claims] A signal converting means inputs a data signal and outputs a signal with a different frequency depending on whether the level of the data signal is high level or low level. A data transmission device comprising a level adjustment circuit whose attenuation rate can be switched, and configured to compensate for level fluctuations due to frequency characteristics of a telephone or the like connected to a subsequent stage by the level adjustment circuit.